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Krill for human consumption: Nutritional value and potential health benefits
Abstract
The marine crustacean krill (order Euphausiacea) has not been a traditional food in the human diet. Public acceptance of krill for human consumption will depend partly on its nutritive value. The aim of this article is to assess the nutritive value and potential health benefits of krill, an abundant food source with high nutritional value and a variety of compounds relevant to human health. Krill is a rich source of high-quality protein, with the advantage over other animal proteins of being low in fat and a rich source of omega-3 fatty acids. Antioxidant levels in krill are higher than in fish, suggesting benefits against oxidative damage. Finally, the waste generated by the processing of krill into edible products can be developed into value-added products.
... The most popular krill species are Euphausia superba (Antarctic krill) and E. pacifica (Pacific krill), and they are most often used in research. Nevertheless, the biggest problem in the production of this crustacean is its high-water content (about 77.9 -83.1 %), as a result of which it spoils rapidly and thus requires virtually immediate processing [55]. ...
... The amino acids composition is shown in Table 1. However, compared to chicken egg protein, krill exhibits lower digestibility and may not be competitive [55]. On the other hand, nowadays, many protein supplements are produced in which E. superba can also be used, but it has to be appropriately processed first. ...
... On the other hand, nowadays, many protein supplements are produced in which E. superba can also be used, but it has to be appropriately processed first. The disadvantage is the presence of fluorine in isolates allowed for human consumption, but it should be kept in mind that the acceptable intake standards for this element should not be exceeded [55,59]. Excess fluoride can lead to poor bone mineralization, damage the brain, kidneys and liver, as well as may harm the fetus [8,43]. ...
Background. Nowadays, the world is confronted with the problem of rapid population growth and constraints on food productivity to meet the nutritional needs of all people. Agriculture and the food industry are facing difficulties in increasing food production as natural goods such as cultivable land area, water and electricity are being depleted. One of the most important dietary components that may start to become scarce is protein. Existing protein sources, especially animal protein, are very detrimental to the climate, hence not only new solutions, but also new and more sustainable protein sources must be sought. Results and conclusion: Some possible new protein sources and other nutrients may include edible insects in the form of flour from e.g. the house cricket (Acheta domesticus), marine algae in the form of powdered Spirulina (Arthrosipra platensis), ocean krill e.g. antarctic krill (Euphausia superba), cultured meat or Single Cell Protein (SCP). While these raw materials have not been widely used to date, their composition and nutritional value may seem promising. Each of these sources has its advantages and disadvantages, but considering the high demand for new foods, they should be given more careful attention, especially regarding their use in the food industry. Due to their content of essential amino acids and, in the case of edible insects, complete proteins, they can be an excellent alternative to conventional food sources. Additionally, due to the fact that they are rich in certain compounds, they can become new functional food with a wide range of applications.
... Krill oil (KO), extracted from Antarctic krill (Euphasia superba), is also a rich source of LC n-3 PUFA. It is different from fish oil since EPA and DHA in KO are mainly bound to phospholipids instead of triglycerides as in fish oil [10,11]. This suggests the potentially higher bioavailability of KO-derived LC n-3 PUFA compared to fish oil. ...
... This suggests the potentially higher bioavailability of KO-derived LC n-3 PUFA compared to fish oil. In addition, KO contains the antioxidant astaxanthin, vitamins, and minerals [11]. Several animal studies and human trials have reported various health benefits of KO, including its anti-inflammatory properties [12] and its therapeutic effects on glucose metabolism [13], brain disorders [14], cardiovascular diseases [15], as well as CRC [16]. ...
... KO is a rich source of LC n-3 PUFA, EPA and DHA, as well as antioxidant astaxanthin [11]. Previous studies have investigated the effects of LC n-3 PUFA or fish oil combined with chemotherapeutic agents in the treatment of cancer [35], and identified that combined treatments of LC n-3 PUFA with chemotherapy decreased the required dose of chemotherapeutic agents, hence the side effects associated with higher doses of chemotherapy. ...
Background
Our in vitro studies demonstrated that krill oil (KO) has anti-cancer potential. This study aimed to compare the anti-cancer effects of KO with a commonly used chemotherapeutic drug, oxaliplatin and to identify the molecular mechanisms associated with KO supplementation in a mouse model of colorectal cancer (CRC).
Methods
Thirty-six male Balb/c mice were randomly divided into six groups. Five groups received standard chow diet supplemented with KO (150 g/kg)), corn oil (150 g/kg), KO combined with ½ dose of oxaliplatin (1.5 mg/kg body weight/3 times per week), corn oil combined with ½ dose of oxaliplatin (1.5 mg/kg body weight/3 times per week), or a full dose of oxaliplatin (3 mg/kg body weight/3 times per week). The control (sham) group received a standard chow diet. Treatments started three weeks before and continued for three weeks after orthotopic CRC induction. The number of metastases, tumour weight and volume were quantified ex-vivo. The expression of cytochrome c, cleaved caspase-9 and -3, DNA damage, PD-L1, PD-L2 and HSP-70 were determined.
Results
A significant reductions in the weight and volume of tumours were observed in mice treated with KO and KO plus a ½ dose of oxaliplatin compared to the sham group, similar to oxaliplatin-treated mice. KO, and KO plus ½ dose of oxaliplatin significantly increased the expression of cytochrome c, cleaved caspase-9 and -3, and DNA damage and decreased expression of PD-L1, PD-L2 and HSP-70 in tumour tissues compared to the sham group.
Conclusions
The in vivo anti-cancer effects of KO are comparable with oxaliplatin. Thus, dietary KO supplementation has a great potential as a therapeutic/adjunctive agent for CRC treatment.
... KM is prepared from an extract of ground whole Antarctic krill that is cooked and dried, resulting in a brownish-orange powder containing around 60% protein with a nutritionally wellbalanced amino acid profile (Table 2). KM is a sustainable source of protein, n-3 phospholipids (PL), feed attractants, and astaxanthin [8]. It has a proximate composition that is similar to FM with an almost identical amino acid profile. ...
... Based on the above-mentioned studies and considering the cost factor associated with KM, an inclusion level of 10-15% is suggested to enhance the fillet pigmentation in salmonids. In addition, KM contains other active substances that might be of benefit, such as vitamin E, A, and B12 [8]. 8 Aquaculture Nutrition ...
... In addition, KM contains other active substances that might be of benefit, such as vitamin E, A, and B12 [8]. 8 Aquaculture Nutrition ...
The interest for krill-based ingredients for aquaculture feed applications has increased steadily in recent years. For decades, there has been a heavy reliance on the limited sources of fishmeal and fish oil in the salmonid aquaculture industry. Further growth in farming of carnivorous fish is dependent on new feed resources becoming available. The only unexploited marine resources of significant biomass are found at lower trophic levels, of which the Antarctic krill (Euphausia superba) has a high potential. Apart from being the biggest single species biomass, Antarctic krill is also rich in nutrients, such as omega-3 polyunsaturated fatty acids, phospholipids, astaxanthin, vitamins, and minerals. This makes Antarctic krill a high-quality source of health-beneficial lipids and proteins. The present article provides an overview on the documented benefits of feeding salmonids (Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss)) with krill products (krill meal, krill oil, and krill hydrolysate), focusing on growth performance (feed intake, growth rate, and feed conversion), fillet quality, slaughter yield, and health benefits in terms of reducing fat accumulation in liver and intestinal tissues. Besides, the article discusses possible future studies, to widen the knowledge on krill benefits in salmonids and to unravel the underlying mechanisms.
... KM has gained attention in the aquaculture industry as a potential source of several important nutrients in fish feeds. For instance, KM typically contains a high-quality protein, often exceeding 56 % on a dry weight basis, as well as a balanced amino acid profile (Hertrampf et al., 2000;Tou et al., 2007;Kaur et al., 2022). Additionally, krill-derived products are also a valuable source of omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are known to play vital roles in fish metabolism, as essential nutrients to be supplied in the diets of marine carnivorous species, like gilthead sea bream (Sparus aurata) (Izquierdo, 2005;Tocher, 2015). ...
... In addition, KM also contains bioactive antioxidant compounds, including choline, selenium as well as astaxanthin and vitamin E, theoretically improving fish overall health, including fish antioxidant status and defenses (Tou et al., 2007). Oxidative stress is defined as a disturbance in the pro-oxidant/antioxidant balance that leads to potential damage and plays a key role in determining fish responses to environmental changes (Halliwell, 2007). ...
... Characterized by a protein content of approximately 60%, exhibiting a balanced amino acid profile and a lipid content of, on average, 25%, KM can play a valuable role in animal nutrition. In the context of human consumption, the lipid fraction undergoes extraction to yield krill oil (KO), containing around 40% phospholipids (PLs) [3,4] with the majority of long-chain omega-3 polyunsaturated fatty acids (n − 3 PUFAs), such as eicosapentaenoic acid (EPA, 20:5n − 3) and docosahexaenoic acid (DHA, 22:6n − 3), residing within the phosphatidylcholine (PC) configuration [5,6]. In contrast, the omega-3 fatty acids of fish oil are incorporated into triglycerides. ...
... From an aquaculture perspective, krill products are further valuable due to their content of bioactive constituents, including cholesterol, minerals, and vitamins [6], as well as water-soluble, low-molecular-weight feed attractants encompassing free amino acids, nucleotides, nucleosides, quaternary ammonium compounds, phospholipids (PLs), biogenic amines, and chitin. These compounds collectively enhance the attractability and palatability of diets [17,18]. ...
Marine sources of omega-3, proteins, and other nutrients are in increasing demand, while supply is struggling to meet this demand increase. A key focus for meeting the need for marine ingredients for human and animal nutrition is ensuring sustainable sourcing for both the oceans as well as other production types. Aker BioMarine is harvesting and producing marine ingredients from krill and this communication is intended to showcase how the harvesting and production of such ingredients are performed in a sustainable way. This communication is written to describe the krill fisheries’ management, to provide demonstration cases from CO2 hot spotting, and show how results from these are used to target GHG emission reduction. The initiatives that are taken to ensure sustainable fishing and production, as well as examples of short- and long-term actions to reduce and minimize the impact of all activities, are provided.
... KM has gained attention in the aquaculture industry as a potential source of several important nutrients in fish feeds. For instance, KM typically contains a high-quality protein, often exceeding 56 % on a dry weight basis, as well as a balanced amino acid profile (Hertrampf et al., 2000;Tou et al., 2007;Kaur et al., 2022). Additionally, krill-derived products are also a valuable source of omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are known to play vital roles in fish metabolism, as essential nutrients to be supplied in the diets of marine carnivorous species, like gilthead sea bream (Sparus aurata) (Izquierdo, 2005;Tocher, 2015). ...
... In addition, KM also contains bioactive antioxidant compounds, including choline, selenium as well as astaxanthin and vitamin E, theoretically improving fish overall health, including fish antioxidant status and defenses (Tou et al., 2007). Oxidative stress is defined as a disturbance in the pro-oxidant/antioxidant balance that leads to potential damage and plays a key role in determining fish responses to environmental changes (Halliwell, 2007). ...
... Over the past ten years, several studies have shown that krill oil has therapeutic potential in the treatment of chronic disorders, including inflammation, cardiovascular disease, hyperlipidemia, arthritis, neurological disorders, kidney disease and diabetes [15][16][17]. Krill oil extracted from Euphausia surperba, a crustacean species found in the Southern Ocean, has been used as an alternative to fish oil due to its high level of long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) [16,17]. Furthermore, it has also been reported that the presence of astaxanthin in krill oil increases the stability of LC n-3 PUFA and protects them from oxidation that may lead to better health outcomes than fish oil [18]. ...
... Over the past ten years, several studies have shown that krill oil has therapeutic potential in the treatment of chronic disorders, including inflammation, cardiovascular disease, hyperlipidemia, arthritis, neurological disorders, kidney disease and diabetes [15][16][17]. Krill oil extracted from Euphausia surperba, a crustacean species found in the Southern Ocean, has been used as an alternative to fish oil due to its high level of long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) [16,17]. Furthermore, it has also been reported that the presence of astaxanthin in krill oil increases the stability of LC n-3 PUFA and protects them from oxidation that may lead to better health outcomes than fish oil [18]. ...
Background:
We have previously reported that the free fatty acid extract (FFAE) of krill oil (KO) significantly inhibits the proliferation and migration, and induces apoptosis of colorectal cancer (CRC) cells. This study aimed to investigate the in vivo efficacy of various doses of KO supplementation on the inhibition of CRC tumour growth, molecular markers of proliferation, angiogenesis, apoptosis, the epidermal growth factor receptor (EGFR) and its downstream molecular signalling.
Methods:
Male Balb/c mice were randomly divided into four groups with five in each group. The control (untreated) group received standard chow diet; and other three groups received KO supplementation at 5%, 10%, and 15% of their daily dietary intake respectively for three weeks before and after the orthotopic implantation of CT-26 CRC cells in their caecum. The expression of cell proliferation marker Ki-67 and angiogenesis marker CD-31 were assessed by immunohistochemistry. The expression of EGFR, phosphorylated EGFR (pEGFR), protein kinase B (AKT), pAKT, extracellular signal-regulated kinase (ERK1/2), pERK1/2, cleaved caspase-7, cleaved poly (ADP-ribose) polymerase (PARP), and DNA/RNA damage were determined by western blot.
Results:
KO supplementation reduced the CRC tumour growth in a dose-dependent manner; with 15% of KO being the most effective in reduction of tumour weight and volume (68.5% and 68.3% respectively, P < 0.001), inhibition of cell proliferation by 69.9% (P < 0.001) and microvessel density by 72.7% (P < 0.001). The suppressive effects of KO on EGFR and its downstream signalling, ERK1/2 and AKT, were consistent with our previous in vitro observations. Furthermore, KO exhibited pro-apoptotic effects on tumour cells as indicated by an increase in the expression of cleaved PARP by 3.9-fold and caspase-7 by 8.9-fold.
Conclusions:
This study has demonstrated that KO supplementation reduces CRC tumour growth by inhibiting cancer cell proliferation and blood vessel formation and inducing apoptosis of tumour cells. These anti-cancer effects are associated with the downregulation of the EGFR signalling pathway and activation of caspase-7, PARP cleavage, and DNA/RNA damage.
... These fatty acids have positively benefit brain development, cardiovascular health and also reduce inflammatory and the other diseases (Frankel, 1980). Fish and krill oils are important omega-3 fatty acid sources and widely used as supplementation (Ellulu, et al., 2015;Tou, Jaczynski, & Chen, 2007). Krill oil is unique due to its high content of omega-3 fatty acid (20-50%) in the form of phospholipids as well as astaxanthin (1.5-2 mg/100 g oil). ...
... Astaxanthin is a strong antioxidant which also potentially prevents cancer, cardiovascular and immunologic diseases (Higuera-Ciapara, Felix-Valenzuela, & Goycoolea, 2006). It has been reported that the omega-3 fatty acids in krill oil have higher bioavailability and oxidative stability than fish oil (Maki, et al., 2009;Tou, Jaczynski, & Chen, 2007) and can also decrease inflammation, hyperlipidemia and diabetes (Maki, et al., 2009). Although those all sources of long chain omega-3 fatty acids have many health benefits, they have low water-solubility which can limit their utilization as additive in water based foods (Walker, Decker, & McClements, 2015). ...
... In addition, they improve patients' immune function and reduce the toxicity and side-effects of chemotherapy [12]. Krill oil, extracted from small crustaceans Euphausia surperba from the Antarctic Ocean, is one of the rich sources of LC n-3 PUFA [13]. The LC n-3 PUFA in krill oil are bound to the phospholipids while in fish oil they are bound mainly to the triglycerides [13,14]. ...
... Krill oil, extracted from small crustaceans Euphausia surperba from the Antarctic Ocean, is one of the rich sources of LC n-3 PUFA [13]. The LC n-3 PUFA in krill oil are bound to the phospholipids while in fish oil they are bound mainly to the triglycerides [13,14]. It has been suggested that the bioavailability of phospholipid bound n-3 PUFA is higher than those bound to triglycerides and this may lead to more health benefits [15,16]. ...
Abstract Background The currently available treatments for colorectal cancer (CRC) are often associated with serious side-effects. Therefore, the development of a novel nutraceutical agent may provide an alternative complementary therapy for CRC. Overexpression of the epidermal growth factor receptor (EGFR) associates with a range of cancers while downregulation of EGFR signalling can inhibit cancer growth. Our previous studies have shown that the free fatty acid extract (FFAE) of krill oil exhibits anti-proliferative and pro-apoptotic properties. This study determines the effects of krill oil extract on the migration of human CRC cells, and its potential role in modulating EGFR signalling pathway and the expression of programmed death ligand 1 (PD-L1). Methods Human CRC cells, DLD-1 and HT-29 were treated with FFAE of KO at 0.03 and 0.12 μL/100 μL for 8 or 24 h. Cell migration was determined by Boyden chamber migration assay. The expression of EGFR, phosphorylated EGFR (pEGFR), protein kinase B (AKT), phosphorylated AKT (pAKT), extracellular signal regulated kinase (ERK1/2), phosphorylated ERK1/2 (pERK1/2) as well as PD-L1 were assessed by western blotting and immunohistochemistry. Results The FFAE of krill oil significantly inhibited cell migration compared to ethanol-treated (vehicle control) cells (P
... lipid and 77.9-83.1% water [2]. Thereinto, krill proteins have high nutritional values and even their biological values are higher than those of other meat and milk proteins, because it contains adequate levels of all essential amino acids [3,4]. However, a great amount of krill is now used to produce low-value commodities such as animal and fish feed [5]. ...
... Total volume of the foam after 30 min formation were recorded and (FS) was evaluated using Eq. (3). ...
A novel protein extraction method of ultrasound-assisted basic electrolyzed water (BEW) was proposed, and its effects on the structural and functional properties of Antarctic krill proteins were investigated. Results showed that BEW reduced 30.9% (w/w) NaOH consumption for the extraction of krill proteins, and its negative redox
potential (−800 ~ −900 mV) protected the active groups (carbonyl, free sulfhydryl, etc.) of the proteins from oxidation compared to deionized water (DW). Moreover, the ultrasound-assisted BEW increased the extraction yield (9.4%), improved the solubility (8.5%), reduced the particle size (57 nm), favored the transition of α-helix
and β-turn to β-sheet, promoted the surface hydrophobicity and disulfide bonds formation of krill proteins when compared to BEW without ultrasound. These changes contributed to the enhanced foam capacity, foam stabilityand emulsifying capacity of the krill proteins. Notably, all the physicochemical, structural and functional properties
of the krill proteins were comparable to those extracted by the traditional ultrasound-assisted DW. This study suggests that the ultrasound-assisted BEW can be a potential candidate to extract proteins, especially offering an alternative way to produce marine proteins with high nutritional quality.
... It is important to note that the application of other sources of LCn-3 PUFA, such as krill oil (Li et al. 2021), might be expected to benefit body composition changes during CR (Munro and Garg 2013a, 2013b, 2012Thorsdottir et al. 2007;Lee et al. 2015;Huerta et al. 2015;Wong et al. 2014). Krill oil contains over 55% of its LCn-3 PUFA in phospholipid form (Tou et al. 2007) and has some choline and astaxanthin, which are important in improving muscle quality and function (Moretti et al. 2020;Liu et al. 2018). Additionally, newly developed LCn-3 PUFA supplements have been formulated, including triglyceride and ethyl ester forms with high concentrations of EPA and DHA (Fu et al. 2018). ...
This systematic review aimed to determine whether caloric restriction‐induced reduction in body fat and fat‐free mass can be amended by supplementation with long‐chain n‐3 polyunsaturated fatty acids. Databases, including PubMed, Google Scholar, Web of Science, and EMBASE, were searched for papers published from the time the databases were created until November 1, 2023. Random‐effects model meta‐analyses were conducted using Review Manager 5.4.1 software. Statistical heterogeneity was assessed using the I². A standardized mean difference with a 95% confidence interval was calculated, and pooled effects were assessed. The initial search identified 1527 articles and 11 studies met the review inclusion criteria with 637 participants included. The participants' ages ranged between 18 and 61 years with a mean body mass index ranging between 27 and 36 kg/m². The changes in fat‐free mass (standardized mean difference = 0.12, 95% CI −0.14 to 0.37, p = 0.36; I²:35%) and fat mass (standardized mean difference = − 0.01; 95% CI −0.25 to 0.24; p = 0.96; I²: 46%) were not different between intervention and control groups. The current review indicates that long‐chain n‐3 polyunsaturated fatty acids supplementation during caloric restriction neither attenuates the decline in fat‐free mass nor enhances the reduction in fat mass. Considering the small number of studies and interventions included, further research is needed to investigate the effectiveness of long‐chain n‐3 polyunsaturated fatty acids supplementation during caloric restriction.
... The inherent nutritional function of krill has spurred extensive research into the potential health benefits they offer, particularly through the consumption of their omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) 114 . Compared to fish-derived omega-3s, the human body can more readily process and utilize krill's essential fats due to their packaging as phospholipids 115 . ...
This study provides a comprehensive update and global overview on the economic value of marine genetic resources from biodiversity beyond national jurisdiction (BBNJ).
Please visit the electronic version at: https://oneworldanalytics.com/bbnj-mgr-report/
The following corrections have been made in the electronic version:
1. A legacy version of Figure 34 used in the pdf version has been updated.
2. The relevant panel of Figure 2 for Level 4 percentage shares by UN region has been updated to reflect the update to Figure 34.
3. The number of publications in the legend for Figure 41 has been corrected to n = 1,749.
... Krill oil is rich in omega 3 fatty acids, astaxanthin, vitamin A and vitamin E. 20 Tables 1, 2, and 3 show the nutritional values of the probiotic yoghurt with 2% krill oil used in the study. Table 4 shows biometric parameters of the rats. ...
The use of calcium, vitamins, minerals, and omega 3 fatty acids during pregnancy are recommended to support the bone development of infants. The aim of this study is to feed pregnant rats with the probiotic yoghurt mixed with krill oil, which is rich in these features, and examine the morphometric development of long bones in their offspring. For this purpose, a total of twelve 2-month-old offspring including 6 in the experimental group (offspring of pregnant rats fed with yoghurt mixed with krill oil) and 6 in the control group (offspring of pregnant rats fed a standard feed), were used in the study. When they became 2 months old, their biometric measurements were taken. After euthanasia, long bones of the offspring (Humerus, antebrachium, femur, ossa cruris) were cleaned by maceration. These bones were photographed. Morphometric measurements of the length and width of these bones were made using the Image J program. In the SPSS (20.0 Version) program, the parameters were compared between the right and left leg bones and between the control and experimental groups by running the Independent Samples T test. Additionally, Pearson’s correlation test was applied between the parameters. The results of the study indicated that this diet with krill oil and yogurt consumed by pregnant rats had positive effects on the length parameters of the bones and biometric parameters of their offspring.
... 3C, the initial a-tocopherol content in raw krill was 98.57 mg kg À1 , which is consistent with the findings of Lu et al. (2015). Like many marine species, krill primarily contains a-tocopherol, a type of vitamin E, known for its role in krill stability, as suggested by Tou et al. (2007). The increase in a-tocopherol content to 132 mg kg À1 (DW) postboiling is attributed to cellular rupture caused by heat, releasing a-tocopherol from lipids (Chen et al., 2022). ...
Boiling, centrifuging and various drying techniques (vacuum freeze‐drying (VFD), vacuum drying (VD), hot‐air drying (HAD) and microwave drying (MWD)) were assessed for their impact on bioactive compounds in Antarctic krill meal. A comparison between the raw and boiling groups revealed a significant degradation and isomerisation of astaxanthin, accompanied by a 1.25‐fold and 1.32‐fold increase in saturated (SFAs) and monounsaturated fatty acids (MUFAs), respectively. Drying was the primary factor responsible for the reduction in phospholipids, α‐tocopherol and polyunsaturated fatty acid (PUFAs), in combination with the increase in thiobarbituric acid‐reactive substances. For different drying methods, it was found that HAD induced severe lipid oxidation. In contrast, the VFD, VD and MWD improved lipid quality, reducing thiobarbituric acid‐reactive substances (TBARS) by 13–22% and increasing phospholipids by 1.08–1.11 times compared to HAD. VD preserved higher levels of bioactive compounds. PLS‐DA analysis identified 13‐cis‐astaxanthin, α‐tocopherol and eleven fatty acids as key indicators for Antarctic krill meal.
... Antarctic krill (AK), with a biomass of more than 27 billion tonnes (Dornan et al., 2022) but only being caught about 450 000 tonnes annually, is a vital marine resource of great potential for use (Tou et al., 2007). AK is rich in amino acids necessary for the human body and polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic (DHA), etc. Besides, the EAAI (essential amino acid index) of Antarctic krill protein is second only to egg protein and higher than milk protein or any other meat protein (Ma et al., 2019). ...
The impact of κ‐carrageenan on the physicochemical structural characteristics of ready‐to‐eat (RTE) Antarctic krill surimi gel (AKSG) was investigated. The modifications in chemical bonding, protein secondary structure, protein composition and microscopic morphology were compared in both gels with and without κ‐carrageenan. According to the findings, adding 4% (w/w) κ‐carrageenan could reduce the cooking loss of AKSG significantly (P < 0.05), enhance the WHC and textural quality of AKSG and RTE AKSG and increase the amount of hydrophobic and disulfide bonds so that the secondary structure of Antarctic krill proteins could be shifted to the β‐sheet. However, there was little impact on the composition of the protein molecules according to the SDS‐PAGE. In addition, the usage of κ‐carrageenan significantly alleviated the disruption of the protein gel network caused by high‐temperature and high‐pressure treatments (P < 0.05). Therefore, applying κ‐carrageenan could effectively enhance the gel quality of RTE AKSG.
... Antarctic krill, thriving in the Antarctic Ocean, stands as Earth's most abundant wild animal, playing a pivotal role in the Antarctic Ocean ecosystem due to its colossal biomass [15,16]. Boasting high levels of protein, EPA, DHA, vitamins, and phospholipids, Antarctic krill products are gaining popularity in human consumption [17,18]. Much research has demonstrated that krill products in feeding with a high-fat diet have been demonstrated to improve dyslipidemia, body weight, and glucose metabolism [19,20]. ...
Background
Due to its enormous biomass, Antarctic krill (Euphausia superba) plays a crucial role in the Antarctic Ocean ecosystem. In recent years, Antarctic krill has found extensive application in aquaculture, emerging as a sustainable source of aquafeed with ideal nutritional profiles. However, a comprehensive study focused on the detailed effects of dietary Antarctic krill on aquaculture animals, especially farmed marine fishes, is yet to be demonstrated.
Results
In this study, a comparative experiment was performed using juvenile P. leopardus, fed with diets supplemented with Antarctic krill (the krill group) or without Antarctic krill (the control group). Histological observation revealed that dietary Antarctic krill could reduce lipid accumulation in the liver while the intestine exhibited no obvious changes. Enzyme activity measurements demonstrated that dietary Antarctic krill had an inhibitory effect on oxidative stress in both the intestine and the liver. By comparative transcriptome analysis, a total of 1,597 and 1,161 differentially expressed genes (DEGs) were identified in the intestine and liver, respectively. Functional analysis of the DEGs showed multiple enriched terms significantly related to cholesterol metabolism, antioxidants, and immunity. Furthermore, the expression profiles of representative DEGs, such as dhcr7, apoa4, sc5d, and scarf1, were validated by qRT-PCR and fluorescence in situ hybridization. Finally, a comparative transcriptome analysis was performed to demonstrate the biased effects of dietary Antarctic krill and astaxanthin on the liver of P. leopardus.
Conclusions
Our study demonstrated that dietary Antarctic krill could reduce lipid accumulation in the liver of P. leopardus, enhance antioxidant capacities in both the intestine and liver, and exhibit molecular-level improvements in lipid metabolism, immunity, and antioxidants. It will contribute to understanding the protective effects of Antarctic krill in P. leopardus and provide insights into aquaculture nutritional strategies.
... By weight, KO is composed of at least 20% EPA and DHA and 40% phospholipid, mainly in the form of phosphatidylcholine (Massrieh, 2008). The binding between phospholipids and long-chain n-3 FAs may help FA molecules pass through the intestinal wall, increase their bioavailability, and ultimately increase the n-3/n-6 ratio (Tou et al., 2007). In our study, the levels of EPA and DHA were significantly higher in M. nipponense individuals fed with animal oils (FO and KO) than in those fed with SO. ...
... KM contains a wellbalanced amino acid profle similar to FM, high levels of phospholipids, n-3 polyunsaturated fatty acids (n-3 PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), astaxanthin, vitamins, minerals, and trimethylamine N-oxide. [16]. Tese nutritional characteristics have made KM an attractive feed ingredient for the aquaculture industry [17]. ...
Intestinal steatosis, called lipid malabsorption syndrome (LMS) in severe cases, is a common condition in farmed Atlantic salmon, associated with choline deficiency causing low lipid transport in enterocytes, excessive lipid accumulation, and increased mucosal weight. A previous dose-response study supplying a plant-based diet with choline chloride indicated that 3.4 g/kg choline prevents LMS in Atlantic salmon. However, no similar documentation exists using phosphatidylcholine (PC) as a choline source. The present study therefore aimed to determine the ability of PC from krill meal (KM) and krill oil (KO) towards reducing steatosis in Atlantic salmon. Two diets with suboptimal PC levels (1.5 and 2.6 g/kg) were tested against two control diets, a choline-deficient diet with no supplementation (0.6 g/kg), and a high choline (4.0 g/kg choline chloride) diet. After 8 weeks of freshwater feeding, growth was significantly higher in KM and KO groups, at both PC levels, in comparison to the choline-deficient group. However, growth was significantly higher only in the KM and KO diets with 2.6 g/kg of PC when compared to the positive control. This indicated that suboptimal levels of PC from KM and KO satisfied choline needs for growth. A clear dose-dependent effect on the decreasing pyloric intestine (PI) somatic index was observed for KM and KO diets, with no significant difference between KM and KO diets (2.6 g/kg choline) and high choline reference diet. Accordingly, PC from both KM and KO significantly reduced lipid accumulation in the PI and liver when added to a choline-deficient diet. However, histological and lipid analyses also indicated that the optimal dietary choline requirement for full elimination of lipid accumulation in PI is higher than 2.6 g/kg with KM and KO as supplementary sources.
... Krill oil also contains potent antioxidants, such as vitamins A and E, flavonoids and astaxanthin. Some studies claim that the association between phospholipids and long-chain omega-3 fatty acids highly facilitates the passage of fatty acid molecules through the intestinal wall, thus increasing bioavailability and their associated health benefits (Richer et al., 2004;Tou, Jaczynski, & Chen, 2007;Werner, Havinga, Kuipers, & Verkade, 2004). Krill is widely used in aquaculture, but the omega-3 market for human consumption is growing rapidly, and krill is becoming increasingly popular as a raw material for dietary supplements (Table 9). ...
This dissertation presents a novel technology aimed at improving the economic feasibility of sourcing metabolites of commercial interest from microalgae. This technology consists of a continuous two-phase algae-crustacean bioreactor where a selected microalgae species is cultured to produce biomass with specific characteristics in the first phase of the reactor. This microalgae biomass is continuously supplied to an interconnected zooplankton culture, which grows while bio-accumulating the algal metabolites or, in some cases, bio-converting them into more valuable compounds. To close the loop, zooplankton waste is used by microalgae as nutrients for growth. The zooplankton biomass produced, which is rich in the desired compound(s), can be manually harvested, avoiding expensive techniques such as centrifugation. Bio-accumulation and bio-conversion concepts have been tested at laboratory and pilot scales with different species configurations. Initially, the creation of a laboratory-scale prototype demonstrated the possibility of producing zooplankton oil with lutein concentrations greater than 1 mg per g oil. Afterwards, a pilot plant was developed to achieve a more detailed understanding of the process and assess productivity. The pilot plant permitted the study of this technology using different biological and environmental setups, which allowed the study of the bio-accumulation of lutein and eicosapentaenoic acid and the bio-conversion of carotenoids and fatty acids into astaxanthin and docosahexaenoic acid. This prototype exhibited a maximum productivity of 3 kg fresh zooplankton biomass per month and m 3. Despite the fact that the proposed culture system presents a reduced productivity in comparison to that of pure microalgae reactors, the implementation of this technology is demonstrated throughout this thesis to possibly represent significant reductions in costs associated with biomass production and processing when compared to the costs of currently used models. Furthermore, the application of this technology may be valuable in different areas such as wastewater bio-remediation, food production and aquaculture.
... 23 Krill has a balanced amino acid profile and a high content of non-protein compounds, especially free amino acids (7%-8% DM). 27,28 The chitin content in krill is around 30 g kg À1 DM, 29 and astaxanthin levels in krill meal were shown to be 37 mg kg À1 , of which 95% were esters. 30 Krill has been considered a palatable, high-quality dietary source of protein, energy and flesh-pigmenting carotenoids for salmon for several decades. ...
Aquaculture is one of the most resource‐efficient and sustainable ways to produce animal protein. The Food and Agriculture Organization predicts that cultivated aquatic species will provide around 53% of the world's seafood supply by 2030. Further growth of intensive farmed aquatic species may be limited by a shortage of feed resources. The aquaculture sector therefore needs to intensify its search for alternative ingredients based on renewable natural resources. A significant increase in production will require an accelerated transition in technology and production systems, better use of natural available resources, development of high‐quality alternative feed resources and exploitation of available space. The present review discusses the urgent need to identify appropriate alternative ingredients for a sustainable future salmonid production. We describe and evaluate the most promising marine ingredients, including low‐trophic species (mesopelagic fish, zooplankton, polychaetes, macroalgae and crustaceans), novel microbial ingredients (bacteria, yeast and microalgae), insects (black soldier fly, yellow meal worm and crickets), animal by‐products (poultry meal, meat and bone meal, blood meal and hydrolysed feather meal) and by‐products from other commercial productions (trimmings and blood). Furthermore, we discuss the available volumes and need for new processing technologies and refining methods to ensure commercial production of nutritionally healthy ingredients. The essential production steps and considerations for future development of sustainable and safe seafood production are also discussed.
... This conservative catch quota and trends in biomass explain why krill stocks count among the best managed and underutilised marine resources to date. Considering the nutritional richness of krill (Tou et al., 2007), this study aimed to assess the potential of krill meal as a compensatory ingredient in practical feeds of the whiteleg shrimp, P.vannamei¸ in combination with significantly reduced fishmeal inclusion. In addition to the shrimp growth performance, the present study focuses on carcass nutrient composition, expression of immune genes, histology of hepatopancreas and haemocyte count in relation to the three different krill meal inclusion levels (2, 4 and 6%) at two different fishmeal inclusion levels (6 and 12%). ...
An eight-week feeding trial was conducted to investigate the effect of dietary krill meal inclusion in diets with moderate (12%) and low (6%) fishmeal concentrations for Penaeusvannamei.Inasmuch, eight iso‑nitrogenous and isolipidic diets were formulated to contain 36% crude protein and 5.5% crude lipid. In the moderate-fishmeal diets, krill meal was included at 0, 2, 4 and 6% (called FK12:0, FK12:2, FK12:4 and FK12:6, respectively), likewise in the low-fishmeal diets, krill meal was included at the same concentrations of 0–6% (called FK6:0, FK6:2, FK6:4 and FK6:6, respectively). Shrimp with a starting body weight of 0.55 ± 0.02 g were stocked at 22 animals per tank of 350 lcapacity and fed three times daily. Results revealed that dietary krill meal and fish meal inclusion levels significantly increased growth performance (P < 0.05)and there was no significant effect on interaction between fishmeal and krill meal levels. Shrimp fed 6% krill meal diet had the highest final body weight of 11.61 g, weight gain of 11.05 g, weight gain % of 1969.38%,specific growth rate of 5.41%/d and yield of 229.42 g/tank The weight gain % and SGR showed non significant difference between 4 and 6% krill meal containing groups.Dietary change did not affect feed conversion ratio, protein efficiency ratio and apparent protein utilization(P > 0.05). Survival was significantly increased in the groups containing 6 and 4% krill meal diets compared to 0% krill meal diet (P < 0.05). Inclusion levels of krill meal showed non-significant differences in post-fed body composition except for crude lipid and crude fibre content. Fishmeal inclusion levels showed significant (P < 0.05) variation in C14:0,C16:0,C18:0,C16:1, C18:1n-9,C18:2n-6,C22:6nn-3/n-6 ratio, whereas krill meal inclusion levels showed significant variation in the all n-3 fatty acids only. Immune-related gene expression was significantly (P < 0.05) upregulated in the shrimp fed high fishmeal diets (12%) for all the analyzed genes (ProPhenoloxidase (ProPO),ProPhenoloxidase activating enzyme (PPAE), Serine Protease (SP), β-1, 3-glucan-binding protein (BGBP), Superoxide dismutase (SOD), and Hemocyanin (HC)). The dietary change led to a significant difference in both histology and haematology parameters (P < 0.05). The results inferred that krill meal could be used as a potential functional feed ingredient in Penaeus vannamei.The present study suggested beneficial effects of krill meal in shrimp diets. The levels of fishmeal inclusion (12 and 6%) also showed significant (P < 0.05) variations in various growth performance parameters. It is plausible that an inclusion level of 4% is the minimum for a measurable difference in growth performance.
... The composition of omega-3 PL products is often very complex, so other constituents may also contribute to the pleiotropic effects of these products. For example, krill oil contains the antioxidant astaxanthin, 96 but also POA, elevated concentrations of which may contribute to the beneficial effects of krill oil on insulin sensitivity in obese mice. 24 POA can also stimulate FA catabolism in the liver via PPARα-dependent AMPK activation. ...
Prevalence of non‐alcoholic fatty liver disease (NAFLD) increases in line with obesity and type 2 diabetes, and there is no approved drug therapy. Polyunsaturated fatty acids of n‐3 series (omega‐3) are known for their hypolipidemic and anti‐inflammatory effects. Existing clinical trials suggest varying effectiveness of triacylglycerol‐ or ethyl ester‐bound omega‐3 in the treatment of NAFLD, without affecting advanced stages such as non‐alcoholic steatohepatitis. Preclinical studies suggest that the lipid class used to supplement omega‐3 may determine the extent and nature of their effects on metabolism. Phospholipids of marine origin represent an alternative source of omega‐3. The aim of this review is to summarize the available evidence on the use of omega‐3 phospholipids, primarily in obesity‐related NAFLD, and to outline perspectives of their use in the prevention/treatment of NAFLD. A PubMed literature search was conducted in May 2021. In total, 1088 articles were identified, but based on selection criteria, 38 original papers were included in the review. Selected articles describing the potential mechanisms of action of omega‐3 phospholipids have also been included. Preclinical evidence clearly indicates that omega‐3 phospholipids have strong antisteatotic effects in the liver, which are stronger compared to omega‐3 administered as triacylglycerols. Multiple mechanisms are likely involved in the overall antisteatotic effects, involving not only the liver, but also adipose tissue and the gut. Robust preclinical evidence for strong antisteatotic effects of omega‐3 phospholipids in the liver should be confirmed in clinical trials. Further research is needed on the possible effects of omega‐3 phospholipids on advanced NAFLD.
... Another source rich in DHA and EPA, but with limited access to humans is a marine organism, known as whale food, namely the krill [78,79]. Krill, the most populous animal species, are small marine crustaceans living in the Arctic seas. ...
Recent advances in functional foods and nutraceuticals have emphasized the beneficial impact of bioactive molecules on human health and longevity. The omega-3 (ω-3) long-chain polyunsaturated fatty acids (LC-PUFAs), namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been shown to exert numerous positive effects on cardiovascular events, inflammatory disease, some cancers, and neurological disorders. The primary sources of ω-3 LC-PUFAs for human consumption are cold-water fish and seafood; however, these are harvested currently beyond a sustainable capacity. Therefore, new sources of ω-3 LC-PUFAs such as oleaginous microalgae are regarded as promising alternatives to fish and seafood. In this context, the aim of the present review is to summarize the recent biotechnological progress made regarding the production, purification, and concentration of ω-3 LC-PUFAs from marine microalgae.
... Antarctic krill (Euphausia superba) is a small marine crustacean organism that has generated strong research interest during the past several years (Xie et al., 2019) as a sustainable source of protein and lipids in aquafeeds (Burri and Nunes, 2016). Based on its nutritional profile, krill meal (KM) contains protein, amino acids and ash levels comparable to that of FM (Hertrampf and Piedad-Pascual, 2000;Tou et al., 2007). Noteworthy is that it presents relatively high levels of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) (Köhler et al., 2015), phospholipids (PLs), vitamins, nucleotides, trimethylamine N-oxide, chitin and natural astaxanthin, which has been demonstrated to stimulate the feeding appetite of fish (Everson et al., 2018), and to efficiently facilitate the reduction of FM and FO in diets (Hatlen et al., 2016;Mørkøre et al., 2020;Saleh et al., 2018;Thakara et al., 2020). ...
A sustainable growth of the aquaculture sector implies the use of sustainable novel raw materials as replacers of the traditional fishmeal (FM) and fish oil (FO) ingredients. This fact has led to the development of sustainable and functional diets as part of a management strategy to reduce the effects on fish growth performance and health derived from low FM/FO dietary contents. In this sense, Antarctic krill (Euphausia superba) is considered a potential candidate in dietary inclusions to potentiate fish growth and health status. In this study, European sea bass (Dicentrarchus labrax) were fed a practical diet with either a 15% fishmeal content (KM0; control diet) or the same diet substituted by 30% (KM5; 5 g KM/kg diet) or 50% (KM7.5; 7.5 g KM/kg diet) Antarctic krill meal (KM) for 12 weeks in triplicates. At the end of the feeding trial, growth performance, liver morphology, liver proximate composition, lipid classes and fatty acid profiles, as well as the expression of hepatic genes related with lipid metabolism were evaluated. Fish fed KM-based diets presented higher (p < 0.05) final weight, protein and lipid efficiency ratios, specific growth rate (SGR) and improved feed conversion ratio (FCR), irrespective of the KM dietary level. Whole body and muscle proximate composition and fatty acid profiles were similar among dietary groups. Livers of European sea bass fed the experimental diets presented similar (p > 0.05) biochemical composition and fatty acid profile. However, smaller hepatocellular area and lower grade of cytoplasm vacuolization as well as a better alignment around sinusoidal spaces were found. The analyses of liver lipid classes revealed a positive correlation between the level of dietary KM and the pigmented material such as astaxanthin and free fatty acid content, as well as a negative correlation with the cholesterol levels. The expression of hepatic genes studied demonstrated a downregulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (hmgr) and delta-6-desaturase (fads2) expression levels in fish fed KM-based diets. Besides, gene expression levels of fatty acid binding protein 7 (fabp7) and lipoprotein lipase (lpl) were significantly correlated with KM dietary levels. Altogether, these results profile KM as a potential promoter of growth and liver health in European sea bass fed low fish meal and oil diets.
... Researchers have discovered a variety of lipid sources with greater potential for use. It was reported that krill oil, a marine oil extracted from Antarctic krill, contained a large amount of n-3 LC-PUFA (especially EPA and DHA), and 30%-65% of the fatty acids were mostly esterified in PLs, which was different from fish oil (mostly esterified in triglycerides) (Tou et al., 2007;Ulven and Holven, 2015). Many studies have proved that dietary krill oil had a beneficial effect on the growth, nutritive value and metabolism of crustaceans, such as Portunus trituberculatus (Yuan et al., 2019a;Yuan et al., 2020;Yuan et al., 2021), Sagmariasus verreauxi (Shu-Chien et al., 2017) and Scylla paramamosain (Li et al., 2021). ...
n-3 LC-PUFA is vital to crustaceans for the growth, molting and development, while the precise molecular mechanism underlying the regulation of n-3 LC-PUFA is poorly investigated. Herein, an 8-week nutritional trial and transcriptome analysis were used to investigate the impacts of dietary n-3 PUFA lipid sources including fish oil (FO), krill oil (KO) and linseed oil (LO) on the transcriptome characteristics in hepatopancreas of swimming crab (Portunus trituberculatus). Crabs fed KO diet had significantly higher percent weight gain (PWG) and molting ratio (MR) than those of crabs fed other diets. The transcriptome analysis reveled that a total of 6567 unigenes were annotated in KEGG database, of which the expression of 1126 significantly altered in the KO vs FO group, while the expression of 921 unigenes changed in the LO vs FO group. The differentially expressed genes (DEGs) in KO vs FO comparison group involved in fat digestion and absorption, ABC transporters, adipocytokine signaling pathway, protein digestion and absorption, glycolysis/gluconeogenesis and HIF-1 signaling pathway. While dietary LO significantly altered the expression levels of genes involved in carbohydrate digestion and absorption, mineral absorption, protein processing in endoplasmic reticulum, glycosphingolipid biosynthesis and insect hormone biosynthesis. In addition, dietary KO significantly up-regulated the expression levels of cyp18a1 (participates in the process of ecdysteroids biosynthesis and further controls the molting of crustaceans), tryp (trypsin-like serine proteinases, resists the pathogen invasion), pla2 (phospholipase A2, regulates different inflammatory processes), ABC transporter (ATP-binding cassette transporter, transports amino acids, lipids and proteins into and out of the cell), cpt1 (carnitine palmitoyltransferase I, the major rate-limiting enzyme of mitochondrial fatty acid β-oxidation) and slc2 (solute carrier 2, mediates bidirectional glucose transport). Meanwhile, dietary LO could significantly down-regulated the expression level of cyp315a1 compared to dietary FO. To sum up, swimming crab fed with dietary krill oil could not only enhance the transport of glucose, lipids, fatty acids and other substrates, but also up-regulate the expression levels of genes related to molting, immunity and energy metabolism to promote molting and growth of swimming crab. The present study revealed the molecular responses of crabs to different dietary n-3 PUFA lipid sources, and further provided important clues with respect to elucidating the molecular mechanisms underlying the regulation of EPA and DHA on the molting and growth of swimming crab.
... An exoskeleton in combination with fast clearance of lactate make krill relatively robust as trawl escapees and may explain their robustness and low escape mortality rate, as also reported in Krafft et al. (2016). Antioxidant levels (e.g., astaxanthin) in krill are especially high, suggesting that they provide benefits against oxidative damage (Tou et al., 2007). Among the various carotenoids, astaxanthin is the most potent known natural antioxidant against oxidative stress (Satoh, 2016). ...
When caught in a trawl, some individuals interacting with the fishing gear may escape, but such interactions may lead to physiological trauma that causes direct delayed mortality and/or increased vulnerability to predation. Understanding fishery-induced stress levels and the recovery period of escapees is therefore crucial for predicting total fishing-induced mortality. Hemolymph lactate concentration is commonly used as an index of physiological stress in many crustacean species, and the clearing time of lactate back to normal levels indicates the ability to recover from stress. We measured the hemolymph lactate concentration in three groups of Antarctic krill (Euphausia superbaDana, 1850): Group 1, trawl escapees collected during fishing; Group 2, specimens subjected to simulated mesh penetration; and Group 3, an onboard acclimated control group. Individuals that had escaped the trawl during fishing had the highest concentrations of hemolymph lactate (mean > 6 mmol–l). Exposure to mesh penetration was in itself not stressful, as hemolymph lactate concentrations did not differ significantly between Group 2 and the control Group (mean 0.8 mmol–lversus 0.7 mmol–l, respectively). Additional stress factors during the capture and handling process likely added to the elevated lactate levels observed in Group 1. For the trawl escapees, the lactate clearance time during stress recovery was modeled as a function of exponential decay. Hemolymph lactate levels did not differ significantly among the three groups after 200 min, which suggested that Antarctic krill recovered from fishery-induced stress within this time period.
... 16,17 With respect to its lipid content in Antarctic krill is one of the richest sources of LC n-3 PUFA, and they contain abundant EPA and DHA, which bind mainly to phospholipids (PLs) along with phosphatidylcholine, whereas in fish oil they mainly bind to triacylglycerols (TAG). 18,19 Numerous studies have reported that the n-3 PUFA attached with PL are more efficiently absorbed and incorporated into cell membranes than TAG, which means that LC n-3 PUFA of krill oil has better bioavailability. 20,21 Additionally, krill oil contains high amounts of astaxanthin, a powerful antioxidant. ...
... In addition, Antarctic krill has a high protein content, estimated to be in the range of 60-65% dry weight Xia et al. 2015). In comparison to other animals, Antarctic krill is a source of lipid-rich high-quality organic compounds, being low in fat and rich in omega-3 fatty acids, and contains all eight of the indispensable amino acids required by adults (Siegel 2000;Tou et al. 2007). Despite its desirable qualities, the food industry has not fully leveraged Antarctic krill for commercial consumption. ...
The Antarctic region is known for its ecological conditions and the presence of some of the rarest microorganisms on earth. Antarctic krill rapidly degrades while at rest or during transport due to high-activity enzymes in its flesh or from microbes. In this study, we analyzed the microbial diversity of the Antarctic krill, Euphausia superba, and identified the dominant bacteria that cause spoilage during storage and transport using culture-independent high-throughput sequencing and microbial pure culture methods. Antarctic krill samples were incubated at temperatures of 0 °C, 4 °C, 16 °C, and 25 °C to determine the microbial diversity and abundance in decaying marine krill samples. Metagenome high-throughput sequencing indicated that, under incubation at 4 °C and 0 °C for 24 h, the microbial diversity of the Antarctic krill samples was high, with high species richness of microbes adapted to the low-temperature environment, as indicated by the overwhelming dominance of Enterococcus and Bacillus. On the other hand, Psychrobacter became the dominant bacteria at storage temperatures of 16 °C and 25 °C. Quantitative PCR results demonstrated that the microbial copy number increased as the temperature increased from 0 to 25 °C, and the quantity of bacteria was much greater than that of fungi under the same storage conditions. Microbial pure culture methods demonstrated that Psychrobacter was the dominant genus at each incubation temperature after 24 h of storage. Psychrobacter sp. and Psychrobacter-like strains isolated from the Antarctic krill samples exhibited protease activity. Our laboratory results indicated that Psychrobacter was the primary cause of spoilage of the Antarctic krill, E. superba. The results from ITS rDNA fungal sequencing showed that unclassified Saccharomycetes were the predominant microbes in all the Antarctic krill samples.
... For example, krill, members of the order Euphausiacea, are found in all oceans of the world. Generally on the small side, ranging from 8 mm to 6 cm (Tou et al. 2007), krill have locked up the bottom of the animal component of most marine food chains, eating phytoplankton and being eaten by basically everything bigger than they are. The Southern Ocean population of Antarctic krill, Euphausia superba, is estimated to weigh about 380 million tons, more than half of which is consumed by the world's whales, penguins, seals, squid, fish, and other animals. ...
Antarctic krills are rapidly frozen onboard into blocks, and therefore, developing technologies that can enable rapid and uniform semi‐thawing and tempering to prevent enzymatic reactions is essential to enhance their quality and commercial value. We evaluate the application of ohmic tempering (OT) in this study. Experimental blocks (4 × 4 × 4 cm³) are processed under OT at 20 kHz and several constant and variable voltages from −30 C to −5°C. Electrical conductivities of the Antarctic krill block and the block's solution are determined in temperature and frequency ranges of −30 C–0°C and 50 Hz to 200 kHz. Better temperature uniformity and reduced OT time are obtained by fine‐tuning the voltage in four steps from 400 to 50 V based on the electrical conductivity (EC) changes to avoid overheating. Compared to conventional tempering methods (air, running water, and low temperature (inside a refrigerator)), OT results in a faster and optimal method. A three‐dimensional heat transfer model for OT is established using COMSOL Multiphysics to explore the OT uniformity of the Antarctic krill block. The simulated temperature profiles are successfully validated using the measured values, confirming good temperature uniformity. Moreover, the simulation revealed hot and cold spots at different positions. At the endpoint of tempering (545 s), the temperature difference between the two spots was 1.364°C using the fine‐tuning method. These results are relevant to the design of novel OT systems.
In the Antarctic marine ecosystem, krill play a pivotal role, yet the intricate microbial community intertwined with these diminutive crustaceans remains largely unmapped. In this study, we successfully isolated and characterized a unique bacterial strain, Pseudoalteromonas sp. WY3, from Antarctic krill. Genomic analysis revealed that WY3 harbors a multitude of genes associated with cold shock proteins, oxidoreductases, and enzymes involved in the osmotic stress response, equipping it with a robust molecular arsenal to withstand frigid Antarctic conditions. Furthermore, the presence of two distinct biosynthesis-related gene clusters suggests that WY3 has the potential to synthesize diverse secondary metabolites, including aryl polyenes and ribosomally synthesized and post-translationally modified peptides. Notably, the identification of genes encoding enzymes crucial for biological immunity pathways, such as apeH and ubiC, hints at a complex symbiotic relationship between WY3 and its krill host. This comprehensive study highlights the robust potential of WY3 for secondary metabolite production and its remarkable ability to thrive at extremely low temperatures in the Antarctic ecosystem, shedding light on the interplay between culturable microorganisms and their hosts in harsh environments, and providing insights into the underexplored microbial communities associated with Antarctic marine organisms and their role in environmental adaptation and biotechnological applications.
Krill oil (KO), extracted from the Antarctic marine crustacean Euphausia superba, is a nutrient-dense substance that includes rich profiles of n-3 polyunsaturated fatty acids (n-3 PUFAs), phospholipids (PLs), astaxanthin (ASX), as well as vitamins A and E, minerals, and flavonoids. As a high-quality lipid resource, KO has been widely used as a dietary supplement for its health-protective properties in recent years. KO has various benefits, including antioxidative, anti-inflammatory, metabolic regulatory, neuroprotective, and gut microbiome modulatory effects. Especially, the antioxidant and anti-inflammatory effects make KO have potential in skin care applications. With increasing demands for natural skin anti-aging solutions, KO has emerged as a valuable nutraceutical in dermatology, showing potential for mitigating the effects of skin aging and enhancing overall skin health and vitality. This review provides an overview of existing studies on the beneficial impact of KO on the skin, exploring its functional roles and underlying mechanisms through which it contributes to dermatological health and disease management.
The burden of osteoarthritis (OA) is rapidly increasing with population aging, but there are still no approved disease-modifying drugs available. Accumulating evidence has shown that OA is a heterogeneous disease with multiple phenotypes, and it is unlikely to respond to one-size-fits-all treatments. Inflammation is recognized as an important phenotype of OA and is associated with worse pain and joint deterioration. Therefore, it is believed that anti-inflammatory treatments may be more effective for OA with an inflammatory phenotype. In this review, we summarized clinical trials that evaluated anti-inflammatory treatments for OA and discussed whether these treatments are more effective in inflammatory OA phenotypes compared to general OA patients.
Background
The Antarctic krill, Euphausia superba ( E. superba ), is a key organism in the Antarctic marine ecosystem and has been widely studied. However, there is a lack of transcriptome data focusing on temperature responses.
Methods
In this study, we performed transcriptome sequencing of E. superba samples exposed to three different temperatures: −1.19 °C (low temperature, LT), − 0.37 °C (medium temperature, MT), and 3 °C (high temperature, HT).
Results
Illumina sequencing generated 772,109,224 clean reads from the three temperature groups. In total, 1,623, 142, and 842 genes were differentially expressed in MT versus LT, HT versus LT, and HT versus MT, respectively. Moreover, Kyoto Encyclopedia of Genes and Genomes analysis revealed that these differentially expressed genes were mainly involved in the Hippo signaling pathway, MAPK signaling pathway, and Toll−like receptor signaling pathway. Quantitative reverse-transcription PCR revealed that ESG037073 expression was significantly upregulated in the MT group compared with the LT group, and ESG037998 expression was significantly higher in the HT group than in the LT group.
Conclusions
This is the first transcriptome analysis of E. superba exposed to three different temperatures. Our results provide valuable resources for further studies on the molecular mechanisms underlying temperature adaptation in E . superba .
The study has been made for examining the effects of phosphatidylserine on children who have ADHD. The study have been written by using quantitative method in the context of diet studies to be done with food supplement. The sample of this study consisted by 6-13 aged children with ADHD diagnosis. The sample is consisted by 30 children, 6 of them are girls and 24 of them are boys. The data were obtained by using Personel Survey Form and Conners’ Parent Rating Scale. The data in the study was transferred to SPSS-16 statistic programme and analyzed by using two-tailed t-test (Paired Samples t Test). The findings of our study Show that a quite similarity with the other studies in literature. When the points distributions are taken from the subscales of Conners’ Parent Rating Scale which is applied before phosphatidylserine supplemention; the great decrease in the all scores they have taken after phosphatidylserine supplemention in “Behavioral Problem” (11,63 vs 4,93, p
Chlorella pyrenoidosa is an excellent source of protein, and in this research, we assessed the antioxidant and emulsifying effects of Chlorella protein hydrolysate (CPH) using neutral proteases and alkaline proteases, as well as the properties of CPH-derived krill oil-in-water (O/W) emulsions. The CPHs exhibited the ability to scavenge several kinds of free radicals, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), O2⁻, hydroxyl, and ABTS. Additionally, the CPHs (5 mg/mL) scavenged approximately 100% of the DPPH and ABTS. The CPHs showed similar emulsifying activities to Tween 20 and excellent foaming activities (max FS 74%), which helped to stabilize the krill oil-in-water emulsion. Less than 10 mg/mL CPHs was able to form fresh krill oil-in-water emulsions; moreover, the CPHs (5 mg/mL) in a krill O/W emulsion were homogenous, opaque, and stable for at least 30 days. Based on their inhibitory effects on the peroxide value (POV) and thiobarbituric acid reactive substances (TRABS), the CPHs were found to be able to inhibit lipid oxidation in both emulsifying systems and krill O/W emulsions. Thus, the CPHs could improve superoxide dismutase (SOD) activities by 5- or 10-fold and decrease the high reactive oxygen species (ROS) level caused by the addition of H2O2 in vitro. In conclusion, health-promoting CPHs could be applied in krill oil-in-water emulsions as both emulsifiers and antioxidants, which could help to improve the oxidative and physical stability of emulsions.
The bioactive compounds known as “bioceuticals” have remarkable potential to be used as active pharmaceutical ingredients and can also be used for designing several nutraceuticals in food supplements. Nowadays, nutraceuticals from marine sources are gaining attention in the supplement and food industries. Natural bioactive molecules produced from marine sources are highly effective as therapeutic agents for various non‐infectious and infectious diseases. Some significant microorganisms produce bioactive secondary metabolites with important biological activities. Nutraceuticals, which include dietary supplements and functional foods, are known to have incredible market potential. The chapter precises marine bioactive natural compounds and their possible application in the food industries as well as in the supplement industries. Furthermore, collaborative and interdisciplinary research are needed among marine microbiologists, scientists, medical practitioners and biotechnologists to provide inventive research and also isolate novel therapeutic molecules having nutraceutical potential.
There are conflicting findings over the bioavailability of long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) from krill oil (KO) compared with fish oil (FO) in short- and long-term studies. The aim of this study was to compare the effects of KO versus FO on the enrichment of molecular species of plasma phospholipids in young women following a 30-day consumption of the n-3 oils. Eleven healthy women aged 18-45 years consumed seven capsules of KO per day (containing a total of 1.27 g n-3 PUFA) or five capsules of FO per day (total of 1.44 g n-3 PUFA) for 30 days in a randomized crossover study, separated by at least a 30-day washout period. Fasting blood samples were collected at day zero (baseline), day 15 and day 30 and analyzed by HPLC-MS/MS for molecular species of phospholipids. Supplementation increased n-3 PUFA in main phospholipids classes in both groups. After 30 days of supplementation, 35 out of 70 molecular species containing eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPAn-3) had a significantly greater concentration in KO group compared with the FO treated group. The majority (89%) of the differentiated molecular species were choline and ethanolamine ether-phospholipids. These data reveal that analysis of plasma phospholipids following 30 days of consumption of KO (a marine oil rich in phospholipids, including ether phospholipids) resulted in an enrichment of n-3 PUFA in molecular species of ether-phospholipids compared with FO (a triacylglycerol-rich marine oil).
Docosahexaenoic acid (DHA), an omega-3 fatty acid rich in seafood, is linked to Alzheimer’s Disease via strong epidemiological and pre-clinical evidence, yet fish oil or other DHA supplementation has not consistently shown benefit to the prevention or treatment of Alzheimer’s Disease. Furthermore, autopsy studies of Alzheimer’s Disease brain show variable DHA status, demonstrating that the relationship between DHA and neurodegeneration is complex and not fully understood. Recently, it has been suggested that the forms of DHA in the diet and plasma have specific metabolic fates that may affect brain uptake; however, the effect of DHA form on brain uptake is less pronounced in studies of longer duration. One major confounder of studies relating dietary DHA and Alzheimer’s Disease may be that adipose tissue acts as a long-term depot of DHA for the brain, but this is poorly understood in the context of neurodegeneration. Future work is required to develop biomarkers of brain DHA and better understand DHA-based therapies in the setting of altered brain DHA uptake to help determine whether brain DHA should remain an important target in the prevention of Alzheimer’s Disease.
Backround
This study aimed to determine the effects of LC n-3 PUFA supplementation on the prevention and treatment of obesity and obesity-related diseases, and to compare the efficiency of different LC n-3 PUFA sources via biochemical and genetic mechanisms in rats.
Methods
Male Wistar rats were randomized into four study groups, and fed with a standard diet, High Fat Diet (HFD), HFD+%2.5 Fish Oil (FO-HFD) or HFD+%2.5 Krill Oil (KO-HFD) for eight weeks. Food consumption, weight gain, serum glucose, insulin, ghrelin and leptin concentrations, lipid profile, liver fatty acid composition, and FADS1 and FADS2 mRNA gene expression levels were measured.
Results
Weight gain in each HFD group was significantly higher than control group ( p < 0.001), without any differences among them ( p < 0.05). LC n-3 PUFAs modified lipid profile, but not glucose tolerance. Serum leptin levels were significantly higher in HFD groups than in the control group, however, no difference in serum ghrelin levels was observed among the groups. Liver n-3 fatty acid desaturation activity was higher ( p = 0.74), and liver total lipid content was lower ( p = 0.86) in KO-HFD compared to FO-HFD. FADS1 gene expression was highest in the HFD group ( p < 0.001) while FADS2 gene expression was highest in the FO-HFD group ( p < 0.001).
Conclusion
LC n-3 PUFAs, especially krill oil, had moderate effects on lipid profile, but limited effects on obesity related parameters, suggesting different effects of different sources on gene expression levels. Further randomized controlled trials are needed to determine the efficacy of different LC n-3 PUFA sources in the prevention and treatment of obesity in humans.
Background:
adequate protein intake is essential to humans and, since the global demand for protein-containing foods is increasing, identifying new high-quality protein sources is needed. In this study, we investigated the acute postprandial bioavailability of amino acids (AAs) from a krill protein hydrolysate compared to a soy and a whey protein isolate.
Methods:
the study was a randomized, placebo-controlled crossover trial including ten healthy young males. On four non-consecutive days, volunteers consumed water or one of three protein-matched supplements: whey protein isolate, soy protein isolate or krill protein hydrolysate. Blood samples were collected prior to and until 180 min after consumption. Serum postprandial AA concentrations were determined using 1H NMR spectroscopy. Hunger and satiety were assessed using visual analogue scales (VAS).
Results:
whey and krill resulted in significantly higher AA concentrations compared to soy between 20-60 min and 20-40 min after consumption, respectively. Area under the curve (AUC) analyses revealed that whey resulted in the highest postprandial serum concentrations of essential AAs (EAAs) and branched chain AAs (BCAAs), followed by krill and soy, respectively.
Conclusions:
krill protein hydrolysate increases postprandial serum EAA and BCAA concentrations in a superior manner to soy protein isolate and thus might represent a promising future protein source in human nutrition.
Docosahexaenoic acid (DHA) is the predominant omega-3 long-chain polyunsaturated fatty acid found in human brain and eyes. There are a number of studies in the literature showing the health benefits of DHA. It is critical throughout all life stages from the need for fetal development, the prevention of preterm birth, and the prevention of cardiovascular disease to the improvements in the cognitive function and the eye health of adults and elderly. These benefits might be related to the modulation of gut microbiota by DHA. In addition, there are some discrepancies in the literature regarding certain health benefits of DHA, and this review is intended to explore and understand these discrepancies. Besides the variations in the DHA contents of different supplement sources, bioavailability is crucial for the efficacy of DHA supplements, which depends on several factors. For example, DHA in phospholipid and triglyceride forms are more readily to be absorbed by the body than that in ethyl ester form. In addition, dietary lipids in meals and emulsification of DHA oil can increase the bioavailability of DHA. Estrogens stimulated the biosynthesis of DHA, whereas testosterone stimulus induced a decrease in DHA. The roles of DHA through human lifespan, the sources, and its recommended daily intake in different countries are also discussed to provide a better understanding of the importance of this review.
Euphausia superba, commonly known as krill, is a small marine crustacean from the Antarctic Ocean that plays an important role in the marine ecosystem, serving as feed for most fish. It is a known source of highly bioavailable omega-3 polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid). In preclinical studies, krill oil showed metabolic, anti-inflammatory, neuroprotective and chemo preventive effects, while in clinical trials it showed significant metabolic, vascular and ergogenic actions. Solvent extraction is the most conventional method to obtain krill oil. However, different solvents must be used to extract all lipids from krill because of the diversity of the polarities of the lipid compounds in the biomass. This review aims to provide an overview of the chemical composition, bioavailability and bioaccessibility of krill oil, as well as the mechanisms of action, classic and non-conventional extraction techniques, health benefits and current applications of this marine crustacean.
With the epidemic of human obesity, dietary fats have increasingly become a focal point of biomedical research. Epidemiological studies indicate that high-fat diets (HFDs), especially those rich in long-chain saturated fatty acids (e.g., Western Diet, National Health Examination survey; NHANES ‘What We Eat in America’ report) have multi-organ pro-inflammatory effects. Experimental studies have confirmed some of these disease associations, and have begun to elaborate mechanisms of disease induction. However, many of the observed effects from epidemiological studies appear to be an over-simplification of the mechanistic complexity that depends on dynamic interactions between the host, the particular fatty acid, and the rather personalized genetics and variability of the gut microbiota. Of interest, experimental studies have shown that certain saturated fats (e.g., lauric and myristic fatty acid-rich coconut oil) could exert the opposite effect; that is, desirable anti-inflammatory and protective mechanisms promoting gut health by unanticipated pathways. Owing to the experimental advantages of laboratory animals for the study of mechanisms under well-controlled dietary settings, we focus this review on the current understanding of how dietary fatty acids impact intestinal biology. We center this discussion on studies from mice and rats, with validation in cell culture systems or human studies. We provide a scoping overview of the most studied diseases mechanisms associated with the induction or prevention of Inflammatory Bowel Disease in rodent models relevant to Crohn’s Disease and Ulcerative Colitis after feeding either high-fat diet (HFD) or feed containing specific fatty acid or other target dietary molecule. Finally, we provide a general outlook on areas that have been largely or scarcely studied, and assess the effects of HFDs on acute and chronic forms of intestinal inflammation.
Preclinical evidence suggests that n-3 fatty acids EPA and DHA (Omega-3) supplemented as phospholipids (PLs) may be more effective than triacylglycerols (TAGs) in reducing hepatic steatosis. To further test the ability of Omega-3 PLs to alleviate liver steatosis, we used a model of exacerbated non-alcoholic fatty liver disease based on high-fat feeding at thermoneutral temperature. Male C57BL/6N mice were fed for 24 weeks a lard-based diet given either alone (LHF) or supplemented with Omega-3 (30 mg/g diet) as PLs (krill oil; ω3PL) or TAGs (Epax 3000TG concentrate; ω3TG), which had a similar total content of EPA and DHA and their ratio. Substantial levels of TAG accumulation (~250 mg/g) but relatively low inflammation/fibrosis levels were achieved in the livers of control LHF mice. Liver steatosis was reduced by >40% in the ω3PL but not ω3TG group, and plasma ALT levels were markedly reduced (by 68%) in ω3PL mice as well. Krill oil administration also improved hepatic insulin sensitivity, and its effects were associated with high plasma adiponectin levels (150% of LHF mice) along with superior bioavailability of EPA, increased content of alkaloids stachydrine and trigonelline, suppression of lipogenic gene expression, and decreased diacylglycerol levels in the liver. This study reveals that in addition to Omega-3 PLs, other constituents of krill oil, such as alkaloids, may contribute to its strong antisteatotic effects in the liver.
The oceans have been the Earth’s most valuable source of food. They have now also become a valuable and versatile source of bioactive compounds. The significance of marine organisms as a natural source of new substances that may contribute to the food sector and the overall health of humans are expanding. This review is an update on the recent studies of functional seafood compounds (chitin and chitosan, pigments from algae, fish lipids and omega-3 fatty acids, essential amino acids and bioactive proteins/peptides, polysaccharides, phenolic compounds, and minerals) focusing on their potential use as nutraceuticals and health benefits.
In this review paper, the latest literature on the functional properties of phospholipids in relation to inflammation and inflammation-related disorders has been critically appraised and evaluated. The paper is divided into three sections: Section one addresses the relationship between the anti-inflammatory bioactivities of different phospholipids in relation to their structures and compositions. Sections two and three are dedicated to the structures, functions and anti-inflammatory properties of dietary phospholipids from animal and marine sources. Most of the dietary phospholipids of animal origin come from meat, egg and dairy products. To date, there is very limited work published on meat phospholipids, undoubtedly due to the negative perception that meat consumption is an unhealthy option due to its putative associations with several chronic diseases. These assumptions are addressed with respect to the phospholipid composition of meat products. Recent research trends indicate that dairy phospholipids possess anti-inflammatory properties, which has led to an increased interest into their molecular structures and reputed health benefits. Finally, the structural composition of phospholipids of marine origin is discussed. Extensive research has been published in relation to ω-3 polyunsaturated fatty acids (PUFAs) and inflammation, however this research has recently come under scrutiny and has proved to be unreliable and controversial in terms of the therapeutic effects of ω-3 PUFA, which are generally in the form of triglycerides and esters. Therefore, this review focuses on recent publications concerning marine phospholipids and their structural composition and related health benefits. Finally, the strong nutritional value of dietary phospholipids are highlighted with respect to marine and animal origin and avenues for future research are discussed.
This is a follow-up of our previous postprandial study and it focused on the plasma lipidomic responses to 30 days of krill oil (KO) versus fish oil (FO) supplementations in healthy women. Eleven women (aged 18-50 years) consumed KO or FO for 30 days in a randomized, cross-over study, with at least a four-week washout period between supplementations. The daily supplements provided 1.27 g/day of long-chain (LC) omega-3 polyunsaturated fatty acids (PUFA) from KO (containing 0.76 g eicosapentaenoic acid (EPA), 0.42 g docosahexaenoic acid (DHA)) and 1.44 g/day from FO (containing 0.79 g EPA, 0.47 g DHA). Fasting plasma samples at days 0, 15, and 30 were analyzed using gas chromatography and liquid chromatography electrospray ionisation-tandem mass spectrometry. KO resulted in a significantly greater relative area under the curve (relAUC) for plasma EPA after 30 days. Lipidomic analysis showed that 26 of 43 lipid molecular species had a significantly greater relAUC in the KO group, while 17/43 showed a significantly lower relAUC compared with the FO group. More than 38% of the lipids species which increased more following KO contained omega-3 PUFA, while where FO was greater than KO, only 12% contained omega-3 PUFA. These data show that KO and FO do not have equivalent effects on the plasma lipidome.
Protein intake that exceeds the recommended daily allowance is widely accepted for both endurance and power athletes. However, considering the variety of proteins that are available much less is known concerning the benefits of consuming one protein versus another. The purpose of this paper is to identify and analyze key factors in order to make responsible recommendations to both the general and athletic populations. Evaluation of a protein is fundamental in determining its appropriateness in the human diet. Proteins that are of inferior content and digestibility are important to recognize and restrict or limit in the diet. Similarly, such knowledge will provide an ability to identify proteins that provide the greatest benefit and should be consumed. The various techniques utilized to rate protein will be discussed. Traditionally, sources of dietary protein are seen as either being of animal or vegetable origin. Animal sources provide a complete source of protein (i.e. containing all essential amino acids), whereas vegetable sources generally lack one or more of the essential amino acids. Animal sources of dietary protein, despite providing a complete protein and numerous vitamins and minerals, have some health professionals concerned about the amount of saturated fat common in these foods compared to vegetable sources. The advent of processing techniques has shifted some of this attention and ignited the sports supplement marketplace with derivative products such as whey, casein and soy. Individually, these products vary in quality and applicability to certain populations. The benefits that these particular proteins possess are discussed. In addition, the impact that elevated protein consumption has on health and safety issues (i.e. bone health, renal function) are also reviewed.
We investigated the effects of various dietary fibers or their likenesses on the apparent fat digestibility by rats fed on a high-fat diet. Each of 23 different fibers was added at 5% (w/w) to a purified diet containing 20% (w/w) corn oil. The rats were fed these diets for 2 weeks, and the feces were collected from each animal during the last 3 days. When compared with cellulose (control), 10 of the tested fibers significantly increased the fecal lipid excretion. Among these fibers, chitosan markedly increased the fecal lipid excretion and reduced the apparent fat digestibility to about a half relative to the control. The apparent protein digestibility was not greatly affected by chitosan. The fatty acid composition of the fecal lipids closely reflected that of the dietary fat. These results suggest that chitosan has potency for interfering with fat digestion and absorption in the intestinal tract, and for facilitating the excretion of dietary fat into the feces. © 1994, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.
Euphausiid IdentificationBroad-scale distributionSynopsis of the book
Epidemiological studies in Greenland Eskimos led to the hypothesis that marine oils rich in n-3 fatty acids (also referred to as omega (omega)-3 fatty acids) are hypolipidemic and ultimately antiatherogenic. Metabolically controlled trials in which large amounts of fish oil were fed to normal volunteers and hyperlipidemic patients showed that these fatty acids (FAs) are effective at lowering plasma cholesterol and triglyceride levels. Although more recent trials using smaller, more practical doses of fish oil supplements have confirmed the hypotriglyceridemic effect, they have shown little effect on total cholesterol levels; hypertriglyceridemic patients have even experienced increases in low density lipoprotein cholesterol (LDL-C) levels of 10-20% while taking n-3 FA supplements. Discrepancies among fish oil studies regarding the effects of n-3 FAs on LDL-C levels may be understood by noting that, in the majority of studies reporting reductions in LDL-C levels, saturated fat intake was lowered when switching from the control diet to the fish oil diet. When fish oil is fed and saturated fat intake is constant, LDL-C levels either do not change or may increase. Levels of high density lipoprotein cholesterol have been found to increase slightly (about 5-10%) with fish oil intake. Plasma apolipoprotein levels change in concert with their associated lipoprotein cholesterol levels. Although the decrease in triglyceride levels appears to result from an inhibition in hepatic triglyceride synthesis, the mechanisms leading to the increases in LDL and HDL have not been determined. Finally, fatty fish or linolenic acid may serve as alternative sources of long-chain n-3 FAs, but further studies will be needed to document their hypolipidemic and/or antiatherogenic effects.
The seasonal variations in the total lipid content, lipid class composition, fatty acid composition, and fatty alcohol composition of Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Krøyer), and T. raschii (M. Sars) have been examined. The total lipid content was highest in the autumn and early winter months and lowest in the spring. In M. norvegica, triacylglycerols served as the only depot lipids, whereas in T. inermis and T. raschii triacylglycerols, wax esters, and glycerophospholipids varied in proportion to the total lipid content. This suggests that glycerophospholipids, as well as wax esters and triacylglycerols, constitute depot lipids in these species. Wax esters and glycerophospholipids were the dominating depot lipids in T. inermis, whereas triacylglycerols and glycerophospholipids were most important in T. raschii. Results suggest that non-depot glycerophospholipids may constitute 3.5-4.5% of the dry weight of the three species of krill examined. T. inermis and T. raschii, from the same catches, had very similar fatty acid compositions for each of the major lipid classes, with the exception of a few minor fatty acids. The major lipid classes in all three species showed complex seasonal variations in the content of the fatty acids that typically reflect the diet, particularly in the case of the triacylglycerols. The results suggest that all the species examined are more herbivorous during the summer than during the autumn and winter. M. norvegica seemed to be significantly more carnivorous than the two Thysanoessa species. The degree of incorporation of individual fatty acids from the diet is probably specific for each lipid class in each krill species. The proportion of polyenoic fatty acids in the glycerophospholipids and the proportion of monoenoic fatty acids in the wax esters may be of importance for the temperature adaptation of T. inermis and T. raschii.
N-Carboxymethylchitosan from crab and shrimp chitosans was obtained in water-soluble form by proper selection of the reactant ratio, i.e. using equimolar quantities of glyoxylic acid and amino groups. HPLC determinations of glyoxylic and glycolic acids, in conjunction with NMR analysis, permitted identification of the structure of the product, which is partly N-mono-carboxymethylated (0.3), N,N-dicarboxymethylated (0.3) and N-acetylated depending on the level of deacetylation of the starting chitosan (0.08-0.15). The preparation can be made successfully even in the presence of large concentrations of glycolic acid. The use of enzymes exerting hydrolysing activity on the high-molecular-weight fractions helps to avoid gel formation during storage and precipitate formation on addition of anti-microbial agents.
The average American diet, which is high in protein and low in fruits and vegetables, generates a large amount of acid, mainly as sulfates and phosphates. The kidneys respond to this dietary acid challenge with net acid excretion, as well as ammonium and titratable acid excretion. Concurrently, the skeleton supplies buffer by active resorption of bone. Indeed, calciuria is directly related to net acid excretion. Different food proteins differ greatly in their potential acid load, and therefore in their acidogenic effect. A diet high in acid-ash proteins causes excessive calcium loss because of its acidogenic content. The addition of exogenous buffers, as chemical salts or as fruits and vegetables, to a high protein diet results in a less acid urine, a reduction in net acid excretion, reduced ammonium and titratable acid excretion, and decreased calciuria. Bone resorption may be halted, and bone accretion may actually occur. Alkali buffers, whether chemical salts or dietary fruits and vegetables high in potassium, reverse acid-induced obligatory urinary calcium loss. We conclude that excessive dietary protein from foods with high potential renal acid load adversely affects bone, unless buffered by the consumption of alkali-rich foods or supplements.
A positive correlation between health and economic prosperity has been widely documented, but the extent to which this reflects a causal effect of health on economic outcomes is very controversial. Two classes of evidence are examined. First, carefully designed random assignment studies in the laboratory and field provide compelling evidence that nutritional deficiency - particularly iron deficiency - reduces work capacity and, in some cases, work output. Confidence in these results is bolstered by a good understanding of the underlying biological mechanisms. Some random assignment studies indicate an improved yield from health services in the labour market. Second, observational studies suggest that general markers of nutritional status, such as height and body mass index (BMI), are significant predictors of economic success although their interpretation is confounded by the fact that they reflect influences from early childhood and family background. Energy intake and possibly the quality of the diet have also been found to be predictive of economic success in observational studies. However, the identification of causal pathways in these studies is difficult and involves statistical assumptions about unobserved heterogeneity that are difficult to test. Illustrations using survey data demonstrate the practical importance of this concern. Furthermore, failure to take into account the dynamic interplay between changes in health and economic status has led to limited progress being reported in the literature. A broadening of random assignment studies to measure the effects of an intervention on economic prosperity, investment in population-based longitudinal socioeconomic surveys, and application of emerging technologies for a better measure of health in these surveys will yield very high returns in improving our understanding of how health influences economic prosperity.
Here is a compilation of much-needed figures to aid dietitians in calculating diets.
Consumption of at least two servings of fish per week is recommended by the American Heart Association (AHA) to achieve cardio-protective effects. However, some fish are contaminated with methylmercury, which may counteract the positive effect of the omega-3 fatty acids, and numerous governments have issued advisories for certain fish species. These mixed messages may be a source of confusion to the consumer and to the health professional. This paper reviews whether it is possible to follow the AHA recommendation for fish consumption while avoiding the risks associated with consuming mercury in amounts in excess of government thresholds.
Soy protein has been used in infant feeding in the West for nearly 100 y. Soy protein infant formulas have evolved in this interval to become safe and effective alternatives for infants whose nutritional needs are not met with human milk or formulas based on cow's milk. Modern soy formulas meet all nutritional requirements and safety standards of the Infant Formula Act of 1980. They are commonly used in infants with immunoglobulin E-mediated cow's milk allergy (at least 86% effective), lactose intolerance, galactosemia, and as a vegetarian human milk substitute. Largely as a result of research in animal models, concerns have been voiced regarding isoflavones in soy infant formulas in relation to nutritional adequacy, sexual development, neurobehavioral development, immune function, and thyroid disease. We discuss the available clinical evidence regarding each of these issues. Available evidence from adult human and infant populations indicates that dietary isoflavones in soy infant formulas do not adversely affect human growth, development, or reproduction.
Shell waste from shrimp Crangon crangon processing is a good source of chitin and proteins, contained on a dry basis of the offals in amounts 17.8% and 40.6%, respectively. The digestion of the shells with proteolytic enzymes allow to recovery of the chitin and nutritionally valuable protein hydrolysate. These products were prepared from the shells preliminarily demineralized with 10% HCl solution at 20°C for 30 min using commercially available Alcalase at 55°C and pH 8.5. Recovered protein hydrolysate contained, on a dry basis, 64.3% of protein (N×6.25), 6.24% lipids and 23.4% of sodium chloride and had, at pH 4.0, a minimum solubility, and 81.7% of total nitrogen in the product. The PER value of the obtained product was 2.99 as compared with that for hydrolysates from capelin (2.64) and beef longissimus dorsi muscle proteins (2.81). The charcoal decolorization of the product decreased the PER and amino acid index (EAA) values from 2.99 and 125.4 up to 2.74 and 123.2, respectively. The total amount of residual small peptides and amino acids directly attached to chitin molecules and resistant to enzymatic hydrolysis depends on degree of hydrolysis (DH) and was about 4.4% at DH value of 30%. Such purity of chitin is sufficient for many purposes.
Antarctic krill (Euphausia superba) is distributed south of 60 °S around the South Pole. The stock of krill is estimated at 360 to 1400 million tons. In 1980 the total amount harvested in the world was 500 thousand tons, mainly by the USSR, followed by Japan. Chemical composition of krill is as follows: moisture 77.9–83.1%, crude protein 11.9–15.4%, chitin and glucides 2%, and crude ash 3%. Nutritive value of krill protein is lower than whole‐egg protein but higher than milk protein. Krill contains large amounts of vitamins A and E. About 70% of krill lipid is unsaturated fatty acids such as oleic, eico‐sapentaenoic acid, and docosahexaenoic acid. Commercial products from krill in Japan are frozen raw krill, frozen boiled krill, peeled krill meat, and others. All of these products are processed on boats in the Antarctic Ocean. Krill products in Japan totaled 271,050 tons in 1986–1987.
Krill (Euphausia superba D.) caught in winter near South Georgia were examined as a raw, intermediate product, precipitate and by product. The following assayes were performed: lipid composition (TLC), fatty acid composition (GC), lipid susceptibility to oxidation, and carotenoids content. The krill harvested in July/August was found to contain about 3% of lipids. The amount of n-3 polyunsaturated fatty acids (PUFA; eicosapentaenoic and docosahexaenoic acids) in total lipids of whole krill accounts for 19.0 ± 1.7% of fatty acids. There was no any lost of n-3 PUFA during processes used to obtain the precipitate and the lipid formula. Euphausia superba is a valuable source of n-3 PUFA, primarily because of their stability in krill.Winter-Krill (Euphausia superba D.) als Quelle für n-3-polyungesättigte FettsäurenIm Winter in der Nähe von South Georgia gefangener Krill (Euphausia superba D.) wird als Roh-, Zwischen-, Fällungs- und Nebenprodukt untersucht. Dabei werden Fettzusammensetzung (TLC), Fettsäurenzusammensetzung (GC), Lipidanfälligkeit zur Oxidation und Carotinoidgehalt bestimmt. Der im Juli/August gefangene Krill enthält etwa 3% Lipide. Die Menge an n-3-polyungesättigten Fettsäuren (PUFA; Eicosapentaen- und Docosahexaensäure in den Gesamtlipiden des Krills beträgt 19,0 + 1,7% der Fettsäuren. Während der Aufarbeitung zum Präzipitat und zum Lipidpräparat trat kein Verlust an n-3-polyungesättigten Fettsäuren auf, Euphausia superba ist eine wertvolle Quelle von n-3 PUFA, vor allem wegen seiner Stabilität im Krill.
The debriding potential of a recently discovered potent enzyme preparation derived from Antarctic krill (Euphausia superba) was compared to a routine non-enzymatic treatment in 31 patients with venous leg ulcers. To assure a reliable interpretation of the cleaning effect, computer image analysis was used to measure wound size and the amount of debris day by day. Krill enzyme treatment was significantly (p < 0.01) better than the non-enzymatic treatment. The necrotic area diminished by 53% while in the control group no reduction of the necrotic area was observed in 7 days. The median time required to clean the ulcer was 7 days in the krill group and 10 days in the control group. Afterwards the ulcers were grafted with autologous skin biopsies, which yielded similar results in both groups. No side effects were observed. It was concluded that krill enzymes fulfil criteria for effective debridement of venous leg ulcers.Copyright © 1999 S. Karger AG, Basel
Chemonucleolysis is a therapeutic procedure whereby a degradative enzyme is injected intradiscally to reduce disc height/width by depolymerisation of extracellular matrix components. This process is considered to diminish disc pressure on inflamed nerve roots, resulting in the alleviation of sciatic pain. In the present study two krill (Euphasia superba) enzyme preparations, a proteinase and an esterase preparation, were evaluated for their potential as chemonucleolytic agents. Initially, their ability to degrade several protein (azocoll, casein, proteoglycans, PGs) and peptide (CBZ-arg-4-nitroanilide, CBZ-lys-thiobenzyl ester) substrates was assessed in vitro. The krill proteinase preparation rapidly converted azocoll, casein and PGs to small peptides. Furthermore, when this degradative enzyme preparation was evaluated in vivo, a relatively low intradiscal dose (0.54 mg/disc) was found to reduce intervertebral disc widths in beagles to 48% ± 10.5% (mean ± SEM) of their pre-injection values within 2 weeks of administration. Moreover, the discs injected with this proteinase had reconstituted up to 80% ± 9% (mean ± SEM) of their pre-injection widths at the termination of the experiment (32 weeks). These data suggest that the krill protease preparation has potential as a chemonucleolytic agent which would allow disc matrix reconstitution. Conversely, the krill esterase preparation also degraded PGs, but into relatively large fragments. This limited digestion of PGs indicates that the krill esterase would be a less effective chemonucleolytic agent than the corresponding proteinase.
Essentially all of the proteins of chicken breast muscle were soluble in sodium chloride solutions of physiological ionic strength or less and neutral pH. However, there was a critical order of treatment necessary to accomplish this. After removal of those proteins solubilized by homogenizing the tissue 1:10 (w/v) in water, it was necessary to solubilize a fraction of the remaining proteins in moderate concentrations (25−150 mM) of sodium chloride at neutral pH before the remaining proteins could be solubilized in water. Solubilization of chicken breast muscle proteins in water could be prevented or reversed by salt solutions of low concentration, suggesting that most of the solubility was not directly caused by proteolysis. SDS−polyacrylamide gel electrophoresis indicated that removal of specific peptides by moderate concentrations of sodium chloride at neutral pH was correlated with removal of the restriction on the water solubility of the remaining proteins. Keywords: Protein solubility; solubility of muscle proteins; chicken muscle protein solubility
Respective utilities of the fresh and frozen (after a 10-month storage at −21 °C) krill for precipitate production by means of partial autoproteolysis within 10–60 °C were compared. The highest yield of the precipitate was found at about 20 °C, regardless of the raw material used, although the optimal temperature ranges for the fresh and frozen krill were 20–30 °C and 10–20 °C, respectively. The main factors assisting the protein extraction during partial autoproteolysis were enzymatic protein hydrolysis in the fresh krill and the loosening of tissues brought about by water crystallization in the frozen krill.
British Columbia krill fisheryNova Scotian krill fisheriesKrill fisheries management
Industrial shrimp waste is a good source of protein, chitin, and carotenoids. In general, this waste is discarded with no attempt to use it, thus contributing to environmental pollution. This study was aimed at recovering the 3 main components of industrial shrimp waste, protein, chitin, and astaxanthin, using enzymatic treatment with Alcalase and pancreatin. An increase in the degree of hydrolysis (DH) from 6% to 12% resulted in 26% to 28% protein recovery. Alcalase was more efficient than pancreatin, increasing the recovery of protein from 57.5% to 64.6% and of astaxanthin from 4.7 to 5.7 mg astaxanthin/100 g of dry waste, at a DH of 12%. The enzymatic hydrolysis of the industrial waste from Xiphopenaeus kroyeri shrimp using Alcalase allowed for 65% protein recovery in the form of hydrolysates, in addition to providing suitable conditions for the recovery of astaxanthin and chitin.
The contributiion of krill to the oceanic produciton of chitin is re-examined using newly published data on the chitin content of Antarctic krill and on the production rate of chitin in the form of exuviae. Calculations suggest that earlier estimates of krill hictin production are likely to be overestimates. Krill are, however, among the major arthropod producers of chitin in the oceans and the Antarctic krill fishery at its current level is still a potential major source of chitin to industry.
Frozen samples of Antarctic krill (Euphausia superba Dana) were found to contain 71·4% moisture, and on a dry matter basis 24·6% lipid, 49% protein (N × 6·25), 2·5% chitin, and 9·8% ash. Fatty acids from the crude lipid fraction were made up of 43·8% saturated, 32·8% mono-unsaturated, and 23·4% polyunsaturated types.
Krill protein concentrate prepared as a light, free-flowing powder by isopropanol extraction of krill contained 74·3% crude protein, 15·4% ash, 6% chitin and 0·3% lipid, and was rich in lysine, arginine, tryptophan, and threonine. The protein efficiency ratio of this concentrate was found to be the same as that of casein.
The significance of these results in relation to those obtained for other fish protein concentrates is discussed.
Wound healing can be accelerated by removing necrotic tissue. Various methods of wound debridement have been developed, including enzymatic debridement. Recently potent proteolytic enzymes were isolated from the intestine of Euphausia superba (Antarctic krill) that might be useful for degrading necrotic tissue. The purpose of this study was to evaluate the debriding properties of krill enzymes, using a specially designed animal model and a computerized analysis system. In 10 female domestic pigs, each weighing 20 kg, 6 artificial ulcers were made on each animal's back using electrokeratome, followed by application of trichloracetic acid. Ulcers were treated twice daily for 7 days with either krill enzymes at different concentrations or with saline. Reduction of necrotic tissue was measured daily using computerized wound analysis. Histological examination included the determination of bromodeoxyuridine incorporation in order to detect cell proliferation as well as routine stains. The debriding effect of krill enzymes at a concentration of ≥ 3.0 casein units per ml was significantly better than saline control treatment (p < 0.05). The effect was dose dependent, and granulation tissue formation was enhanced. In conclusion, krill enzymes are effective in wound debridement, as measured in this animal model.
IntroductionConstraints to using krillCurrent uses of krillTrends and future developmentsNotes
The fluoride content of whole animals and different tissues of the euphausiid species Euphausia superba and Meganyctiphanes norvegica was analyzed by two different and improved methods of isolation and determination. In contrast to other authors our findings show that the internal organs (muscle, hepatopancreas and hemolymph) contain less than 6 ppm d.w. fluoride this being the same order of magnitude as for vertebrates. The high concentrations reported by other authors must be mainly due to contamination of the soft tissue during storage (post-mortem migration of fluoride from shell) and/or contamination caused by minute fractions of cuticle during dissection. Over 99% of the total fluoride content is located in the cuticle (i.e. integument) of the euphausiids (2600 ppm/d.w. in E. superba and 3300 ppm/d.w. in M. norvegica in pleon cuticle). Analysis of F- levels in relation to the moulting cycle showed that the uptake in both euphausiids occurs at a comparable and fast rate during the same physiological phase shortly after moult, parallel to the general construction of the cuticle. The internal organs show homeostasis in respect to fluoride. Accordingly, no internal deposition takes place, and F- is reaccumulated from the external medium at each moult.
Nyctiphanes australis contained, on a dry weight basis, an average of 52% crude protein and 5.0 to 9.5% lipid. The fatty acid profile of N. australis was markedly unsaturated, with a mean total 3 fatty acid content of 48.62.4% of total fatty acids. N. australis contained high levels of the essential long-chain polyunsaturated fatty acids eicosapentaenoic (EPA, 20:53) and docosahexaencic (DHA, 22:63), ranging from 16.6 to 36.5% and 11.1 to 24.8%, respectively. The concentration of total carotenoids ranged from 137 to 302 g g–1 dry wt, with no significant differences in concentrations found with season or life stage. The carotenoids were comprised of 79.5% astaxanthin and 20.5% canthaxanthin. The lipid and pigment compositions of N. australis suggest that the species could serve as a suitable feed source for cultured salmonids. Like other euphausiids, N. australis contained high levels of fluoride, with a seasonal range between 277 and 3507 g g–1 dry wt. The high fluoride levels found in N. australis would not detract from its potential as a feed source for salmonids because ingested fluoride is largely absorbed by the skeleton.
The U.S. Department of Agriculture is searching the world literature published since 1960 for data on food lipids and their
fatty acid composition. These data are being used to update and expand the national tables of food composition and to establish
a computerized nutrient data bank. Customarily, investigators report fatty acid data in terms of weight percent of total methyl
esters. For the benefit of users of nutrient tables, relative amounts of com-ponent fatty acid esters should be converted
to grams fatty acid (as free acid) per 100 grams food. For this purpose, conversion factors, defined as the weight of fatty
acids in 1 gram of fat, were derived for various food products. Derivation of, and basis for, factors and their application
are described for selected food products. Variables affecting factors are also dis-cussed. Investigators should include, in
reports on fatty acid composition of foods, information on total lipid content and on the fatty acid content of the lipid.
The latter values are readily obtained by a saponification procedure, complete acid hydrolysis, or if desired, by lipid class
analysis.
1.1. The lipids of two Antarctic euphausiids were characterized.2.2. In Euphausia superba complex lipids were the major lipid class followed by triglycerides.3.3. In E. crystallorophias the complex lipids were also the major lipid class, but the second major constituent was waxes.4.4. The complex lipids of both euphausiids consisted mostly of phosphatidylcholine with smaller amounts of phosphatidylethanolamine and lysophosphatidylcholine. The phospholipids of E. crystallorophias were less unsaturated than those of E. superba.5.5. The waxes of E. crystallorophias were mostly esters of oleic (84%) and palmitoleic (10%) acids with (69%) and (28%).
The debriding potential of a recently discovered potent enzyme preparation derived from Antarctic krill (Euphausia superba) was compared to a routine non-enzymatic treatment in 31 patients with venous leg ulcers. To assure a reliable interpretation of the cleaning effect, computer image analysis was used to measure wound size and the amount of debris day by day. Krill enzyme treatment was significantly (p less than 0.01) better than the non-enzymatic treatment. The necrotic area diminished by 53%, while in the control group no reduction of the necrotic area was observed in 7 days. The median time required to clean the ulcer was 7 days in the krill group and 10 days in the control group. Afterwards the ulcers were grafted with autologous skin biopsies, which yielded similar results in both groups. No side effects were observed. It was concluded that krill enzymes fulfil criteria for effective debridement of venous leg ulcers.
Proximate composition, minerals, fatty acids, and sterols were determined for eight species of shellfish commonly marketed in the Northwest. Moisture and total lipid content varied with the size of the species, with more variation in mollusca than in crustacea; total lipid content ranged from 0.7% in sea scallops to 3.1% in blue mussels but only from 1.2% in Dungeness crab to 1.3% in pink shrimp. The mineral content was highly variable; the mineral content of Northwest samples tended to be lower than that reported in other studies. Generally, shellfish are good sources of zinc, and Pacific oysters, blue mussels, and Manila clams are also good sources of iron. Five fatty acids (16:0, 16:1, 18:1, 20:5n-3, and 22:6n-3) represented from 60% to 84% of the fatty acid content. Palmitic acid ranged from 13% to 32% of the total fatty acids. Long-chain n-3 polyunsaturated fatty acids were predominant (37.6% to 54.3%), with sea scallops containing more than 50%; n-6 polyunsaturated fatty acids ranged from 1.5% to 6.5%. In crustacea, cholesterol was the primary sterol, and brassicasterol was the only other measurable sterol. In all mollusca except California squid, cholesterol averaged 37 mg/100 gm and ranged from 23% to 39% of the total sterols. In squid, cholesterol, at 231 mg/100 gm, was the only measurable sterol. We conclude that shellfish vary widely in their nutrient content but, in general, are valuable additions to the diet.
Two semi-purified diets, identical except for protein (soya or casein), and a Purina chow diet were fed to groups of Sprague-Dawley rats and compared over a 22-month period for effects on body weight, organ weight, feed consumption, feed efficiency, protein efficiency, organ-to-body-weight ratios, certain organ mineral levels, gross pathology and histopathology. Feed efficiency, protein efficiency, body weight, and most organ weights were higher in the groups fed soya and casein, while feed consumption and most organ-to-body-weight ratios were relatively lower. Significant increases in the final pathology findings in the groups fed soya and casein included nephrocalcinosis (in females), hepatocellular vacuolization, gastric trichobezoars (hairballs), ulcerative pododermatitis (hock ulcers) and splenomegaly. This study demonstrates that the long-term feeding of semi-purified diets is feasible. Moreover, the differences observed between the protein sources, that is, soya and casein, were minimal, which suggests that either protein source is acceptable for long-term feeding studies.
A protease extract from Antarctic krill (E. superba) intended as a new enzymatic debrider for necrotic ulcers has been characterized by sodium dodecyl sulphate polyacrylamide gradient gel electrophoresis and fast protein liquid chromatography. The predominant enzymes in the preparation represent trypsin-like activity associated with three serine proteinases. In addition two carboxypeptidases A and B are present as cooperative enzymes for a more complete breakdown of complex proteinaceous substrates. Biological studies on a well-defined substrate (fibrin) originating from leg ulcers, demonstrated more effective degradation by krill enzymes than bovine trypsin, a common component in marketed enzymatic debriders. These findings support previously in vitro/in vivo studies in an animal model (rat) using excised rat skin as "necrotic" tissue.
Studies have been conducted on the absorbability of individual sterols from a mixture of oyster sterols when administered intragastrically to rats with indwelling catheters in the left thoracic duct. In addition, the effect of oyster sterols on cholesterol absorption has been assessed using [4-14C] cholesterol in the mixture, and comparison against absorption of cholesterol alone. The order of absorbability (percentage absorption) of individual sterols from the mixture of oyster sterols was: cholesterol greater than or equal to 26-carbon sterols greater than or equal to dehydrocholesterol greater than 24-methylene cholesterol greater than brassicasterol greater than plant sterols. The absorption of noncholesterol sterols was 8.2 +/- 0.8% of the fed dose, or less than half of that for an equivalent level of cholesterol alone. The presence of these sterols in mixtures containing cholesterol reduced lymphatic absorption of cholesterol by 25 to 40% compared to absorption of the same amount of cholesterol administered alone, or to an amount of cholesterol equal to the total oyster sterols, respectively. These studies suggest that shellfish sterols are poorly absorbed, and, like plant sterols, effectively reduce dietary and/or endogenous cholesterol absorption from the intestine.
Chemonucleolysis is a therapeutic procedure whereby a degradative enzyme is injected intradiscally to reduce disc height/width by depolymerisation of extracellular matrix components. This process is considered to diminish disc pressure on inflamed nerve roots, resulting in the alleviation of sciatic pain. In the present study two krill (Euphasia superba) enzyme preparations, a proteinase and an esterase preparation, were evaluated for their potential as chemonucleolytic agents. Initially, their ability to degrade several protein (azocoll, casein, proteoglycans, PGs) and peptide (CBZ-arg-4-nitroanilide, CBZ-lys-thiobenzyl ester) substrates was assessed in vitro. The krill proteinase preparation rapidly converted azocoll, casein and PGs to small peptides. Furthermore, when this degradative enzyme preparation was evaluated in vivo, a relatively low intradiscal dose (0.54 mg/disc) was found to reduce intervertebral disc widths in beagles to 48% +/- 10.5% (mean +/- SEM) of their pre-injection values within 2 weeks of administration. Moreover, the discs injected with this proteinase had reconstituted up to 80% +/- 9% (mean +/- SEM) of their pre-injection widths at the termination of the experiment (32 weeks). These data suggest that the krill protease preparation has potential as a chemonucleolytic agent which would allow disc matrix reconstitution. Conversely, the krill esterase preparation also degraded PGs, but into relatively large fragments. This limited digestion of PGs indicates that the krill esterase would be a less effective chemonucleolytic agent than the corresponding proteinase.
We investigated the mechanism for the inhibition of fat digestion by chitosan, and the synergistic effect of ascorbate. The important inhibition characteristics of fat digestion by chitosan from observations of the ileal contents were that it dissolved in the stomach and then changed to a gelled form, entrapping fat in the intestine.
The synergistic effect of ascorbate (AsA) on the inhibition of fat digestion by chitosan is thought not to be acid-dependent but due to the specificity of AsA itself, according to the data resulting from using preparations supplemented with sodium ascorbate (AsN). The mechanism for the synergistic effect is considered to be 1) viscosity reduction in the stomach, which implies that chitosan mixed with a lipid is better than chitosan alone, 2) an increase in the oil-holding capacity of the chitosan gel, and 3) the chitosan–fat gel being more flexible and less likely to leak entrapped fat in the intestinal tract.
Menhaden fish oil (FO) containing n-3 fatty acids dramatically extends the life span and delays the onset and progression of autoimmune disease in (NZBxNZW)F1 (B/W) female mice as compared to those fed corn oil (CO) rich in n-6 lipids. As an inefficient antioxidant defense system has been linked to autoimmune diseases, the present study was undertaken to determine whether the protective action of n-3 lipids is mediated through their antioxidant defense system. Weanling B/W mice were fed a nutritionally adequate, semipurified diet containing CO or krill oil (KO) or FO at 10% level (w/w) ad libitum until the mice were 6.5 months old. All diets contained the same level of vitamin E (21.5 mg/100 g diet). We compared the effects of feeding n-6 and n-3 lipids on survival, kidney disease, hepatic microsomal lipid composition, peroxidation, and on the activity and mRNA expression of the antioxidant enzymes catalase, glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in 6.5-month-old B/W mice. The results showed that when compared to livers from CO-fed mice, livers from KO- and FO-fed mice showed: (i) significantly higher (P < 0.001) activities and expression of CAT, GSH-Px and SOD; (ii) significantly lower (P < 0.001) arachidonic acid (20:4n-6) and linoleic acid (18:2n-6) and higher (P < 0.001) eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) levels in hepatic microsomes; and (iii) significantly lower (P < 0.001) estimated peroxidation indices and thiobarbituric acid reactive substances generation.(ABSTRACT TRUNCATED AT 250 WORDS)
Study of the effects of squid liver fat and krill meat on blood serum atherogenic characteristics in patients with type I diabetes has shown that these foodstuffs had a certain atherogenic effect, for their consumption was associated with a marked reduction of blood serum atherogenicity. The mechanism of this effect is still to be researched.
This review examines the effects of n-3 fatty acids on serum lipid and lipoprotein concentrations in seven species of experimental animals. n-3 Fatty acids consistently lower serum triacylglycerol concentrations in humans but not in most animals. In addition, a common effect of n-3 fatty acids in animals is a marked reduction in high-density-lipoprotein-cholesterol concentrations, a response virtually never seen with fish-oil supplementation in humans. These differences between animals and humans arise not only from underlying species differences in lipoprotein metabolism but also from differences in experimental designs, the most notable of which is the tendency to feed animals much larger amounts of n-3 fatty acids than supplements provide for humans. Thus, great care must be taken not only to use appropriate animal models when studying lipoprotein metabolism but also to feed the animals comparable amounts of n-3 fatty acids. Failure to properly address these issues will make it difficult to uncover the biochemical basis for the hypolipidemic effect of fish oils in humans through use of experimental animals.
The bioavailability of fluoride from krill exoskeleton and the effect of additional calcium on the bioavailability of fluoride from krill paste were evaluated using young rats. Fluoride from the exoskeleton showed a high apparent absorption of 80%. Approximately 3.6% of this fluoride was deposited in the femur, and 44% in the rest of the carcass. The presence of 1.5% and 2.5% calcium (CaCO3) in the diet--1.0 and 2.0% above the minimum recommended content respectively--significantly reduced the bioavailability of fluoride from krill paste. The apparent absorption of fluoride from the paste was reduced by 33.8 and 45.8%, deposition in the femur by 48.1 and 58%, and retention in the rest of the carcass by 44.4 and 55.6%, respectively. The need for further studies using lower amounts of fluoride and calcium and other chemical forms of calcium is indicated.
This document presents guidelines for reducing the risk of cardiovascular disease by dietary and other lifestyle practices. Since the previous publication of these guidelines by the American Heart Association,1 the overall approach has been modified to emphasize their relation to specific goals that the AHA considers of greatest importance for lowering the risk of heart disease and stroke. The revised guidelines place increased emphasis on foods and an overall eating pattern and the need for all Americans to achieve and maintain a healthy body weight (Table⇓).
View this table:
Table 1.
Summary of Dietary Guidelines
The major guidelines are designed for the general population and collectively replace the “Step 1” designation used for earlier AHA population-wide dietary recommendations. More individualized approaches involving medical nutrition therapy for specific subgroups (for example, those with lipid disorders, diabetes, and preexisting cardiovascular disease) replace the previous “Step 2” diet for higher-risk individuals.
The major emphasis for weight management should be on avoidance of excess total energy intake and a regular pattern of physical activity. Fat intake of ≤30% of total energy is recommended to assist in limiting consumption of total energy as well as saturated fat. The guidelines continue to advocate a population-wide limitation of dietary saturated fat to <10% of energy and cholesterol to <300 mg/d. Specific intakes for individuals should be based on cholesterol and lipoprotein levels and the presence of existing heart disease, diabetes, and other risk factors. Because of increased evidence for the cardiovascular benefits of fish (particularly fatty fish), consumption of at least 2 fish servings per week is now recommended. Finally, recent studies support a major benefit on blood pressure of consuming vegetables, fruits, and low-fat dairy products, as well as limiting salt intake (<6 grams per day) and alcohol (no more than 2 drinks per day for men and …
During the past several decades, reduction in fat intake has been the main focus of national dietary recommendations to decrease risk of coronary heart disease (CHD). Several lines of evidence. however, have indicated that types of fat have a more important role in determining risk of CHD than total amount of fat in the diet. Metabolic studies have long established that the type of fat, but not total amount of fat, predicts serum cholesterol levels. In addition, results from epidemiologic studies and controlled clinical trials have indicated that replacing saturated fat with unsaturated fat is more effective in lowering risk of CHD than simply reducing total fat consumption. Moreover, prospective cohort studies and secondary prevention trials have provided strong evidence that an increasing intake of n-3 fatty acids from fish or plant sources substantially lowers risk of cardiovascular mortality. In this article, we review evidence from epidemiologic studies and dietary intervention trials addressing the relationship between dietary fat intake and risk of CHD, with a particular emphasis on different major types of fat, n-3 fatty acids and the optimal balance between n-3 and n-6 fatty acids. We also discuss the implications of the available evidence in the context of current dietary recommendations.
To compare the effects of chitosan and orlistat on fecal fat excretion.
A randomized, open-label, two-period sequential design study was used. A total of 12 healthy adult volunteers within 20% of their ideal body weight entered a 7-day run-in diet period before being randomized to orlistat (120 mg) or chitosan (890 mg) three times daily for 7 days. Subjects then crossed over treatment regimens for an additional 7-day period. Subjects followed a standardized diet (2500 kcal/d, 30% as fat) for the entire 21-day study. Feces were collected on days 4 to 7 of the run-in period (baseline) and during the two treatment periods. Mean daily fecal fat excretion was measured at baseline and during each treatment regimen.
Mean baseline fecal fat excretion for all subjects was 1.36 +/- 0.45 g/d. During orlistat treatment, mean fecal fat excretion significantly increased from baseline (+16.13 +/- 7.27 g/d; p < 0.001). No significant effect was observed with chitosan (+0.27 +/- 1.02 g/d; p = 0.379). Fecal fat excretion was significantly greater with orlistat than with chitosan (p < 0.001; 95% confidence intervals: 11.73; 20.00 g/d).
This study provides additional evidence of the inhibitory effect of orlistat on dietary fat absorption. Chitosan, however, has no effect on fecal fat excretion.
Dietary factors other than the traditional nutrients are found in the so-called functional foods. They are becoming increasingly recognized as potentially important for maintaining good health. Soybeans are rich in such factors thought to help prevent certain chronic diseases. Soy protein isolate (SPI) is one of the three major proteins used in infant formulas sold in the United States, with casein (CAS) and whey (WPH) proteins being the others. We have been studying the health effects of these proteins. Safety concerns have developed over the consumption of soy-based infant formula, partly because of the high circulating levels of the total isoflavones (phytoestrogens) during "critical periods of infant development." There is a paucity of data on developmental, physiological, neurophysiological, behavioral, metabolic, or molecular effects of soy phytochemicals in humans, especially during pregnancy and infancy. We have studied the effects of CAS, SPI, and WPH in short-term, long-term, and multigenerational studies in rats. Aside from minor differences in body weight gain profiles, CAS-, SPI- or WPH-fed rats did not differ in development, organ weights, in vitro hepatic metabolism of testosterone (T), or reproductive performance. However, some endocrine-related functions differed between rats fed these proteins. We found that SPI accelerated puberty in female rats (p < .05) and WPH delayed puberty in males and females, as compared with CAS (p < .05). Gender differences were also found in gonadectomy-induced steroid responses. Male rats had normal serum T levels, but female rats fed SPI had reduced serum 17beta-estradiol concentrations and a blunted 17beta-estradiol response to ovariectomy, as compared to rats fed CAS or WHP (p < .05). Female rats fed SPI or WHP or treated with genistein had reduced incidence of chemically induced mammary cancers (p < .05) compared to CAS controls, with WHP reducing tumor incidence by as much as 50%, findings that replicate previous results from our laboratory. Together, these results suggest gender-specific differences in development and certain endocrine responses among rats fed diets composed of a single protein source such as those used in infant formulas. Whether similar developmental effects occur in human infants is unknown, but unlikely because (1) most infants do not consume such diets throughout life as these rats did, and (2) no such effects have been reported in millions of American infants fed infant formula containing these proteins. The long-term health consequence implications of early diet exposure to SPI and WPH, such as reduced breast cancer incidence, are likely to be very positive.
This paper deals with enzymatic removal of dental plaque, in vitro as well as in vivo, using proteases from the Antarctic krill shrimp (Euphausia superba), referred to as Krillase. Krillase exhibits both endo- and exopeptidase activity but has no microbicidal effect. In model systems with pure cultures of oral microorganisms. Krillase demonstrated inhibition of microbial adhesion to saliva-coated hydroxyapatite. Furthermore, a protocol for the growth of reproducible in vitro plaque films has been developed, and effects of Krillase on the plaque film were investigated by means of scanning electron microscopy (SEM). The results showed that Krillase efficiently released microorganisms from plaque in vitro, the effect being dependent on the enzymatic activity. The surface energy of the substratum had a minor influence on the formation and removal of plaque in vitro. Ellipsometric studies on the formation and enzymatic removal of a salivary pellicle indicated that the enzymatic effect on plaque may partly depend on degradation of the salivary pellicle. Krillase was also able to remove plaque accumulated on dentures in vivo. Our results demonstrate the potential of Krillase for plaque control, and that these enzymes are worthy of further investigations including clinical studies and work to find a suitable vehicle.
Chitosan (CAS 9012-76-4) is derived by alkaline deacetylation from chitin, an abundant polymeric product of natural biosynthesis especially in crustaceans. It is available in a primary, unorganised structure, but also in a microcrystalline form. As a dietary supplement, chitosan has been claimed to control obesity and to lower serum cholesterol. A variety of chitosan products have been freely available worldwide in health stores and pharmacies. This review summarises the current knowledge about cholesterol-lowering and safety properties of chitosan and focuses its possible application for the treatment of hypercholesterolaemia. Chitosan behaves as a polycationic(+) cellulose-like fibrillar biopolymer that forms films with negatively charged surfaces. It is not specifically hydrolysed by digestive enzymes in man, but limited digestion of chitosan due to bacterial flora and to the unspecific enzymes might occur. Negatively charged molecules in stomach attach strongly to the positive charged tertiary amino group (-NH3+) of chitosan. Therefore, chitosan reduces fat absorption from gastrointestinal tract by binding with anionic carboxyl groups of fatty and bile acids, and it interferes with emulsification of neutral lipids (i.e., cholesterol, other sterols) by binding them with hydrophobic bonds. In short-term animal studies the safety of chitosan has been good. There are only few studies with chitosan in humans. In man, dietary chitosan has been reported to reduce serum total cholesterol levels by 5.8-42.6% and low-density lipoprotein levels by 15.1-35.1%. In short-term trials up to 12 weeks, no clinically significant symptoms have been observed with chitosan compared to placebo. Mild and transitory nausea and constipation have been reported in 2.6-5.4% of subjects. Although chitosan has been clinically well tolerated, it cannot be recommended to people allergic to crustaceans.