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Milk fat globules, a novel carrier for delivery of exogenous cholecalciferol
... An optimized sample preparation procedure was used to determine the size distribution of MFG in human milk samples [31]. The frozen milk samples were gently thawed at 4 • C for 3 days according to [32], processed, and the size of the MFG was measured immediately. All milk samples were diluted with Milli-Q water at 9:1 water to milk (v/v), and the cream was separated via centrifugation at 3000× g for 5 min at room temperature. ...
... The collected cream was reconstituted in water at 4% (w/v) and centrifuged at 3000× g for 5 min at room temperature. The cream was then collected and reconstituted in water at 20% (w/v) concentration [32]. After that, 35 mM EDTA (pH 7.0) was added at a 1:5 (v/v) ratio. ...
Human milk provides bioactive compounds such as milk fat globules (MFGs), which promote brain development, modulate the immune system, and hold antimicrobial properties. To ensure microbiological safety, donor milk banks apply heat treatments. This study compares the effects of heat treatments and homogenization on MFG’s physicochemical properties, bioactivity, and bioavailability. Vat pasteurization (Vat-PT), retort (RTR), and ultra-high temperature (UHT) were performed with or without homogenization. UHT, RTR, and homogenization increased the colloidal dispersion of globules, as indicated by increased zeta potential. The RTR treatment completely inactivated xanthine oxidase activity (a marker of MFG bioactivity), whereas UHT reduced its activity by 93%. Interestingly, Vat-PT resulted in less damage, with 28% activity retention. Sialic acid, an important compound for brain health, was unaffected by processing. Importantly, homogenization increased the in vitro lipolysis of MFG, suggesting that this treatment could increase the digestibility of MFG. In terms of color, homogenization led to higher L* values, indicating increased whiteness due to finer dispersion of the fat and casein micelles (and thus greater light scattering), whereas UHT and RTR increased b* values associated with Maillard reactions. This study highlights the nuanced effects of processing conditions on MFG properties, emphasizing the retention of native characteristics in Vat-PT-treated human milk.
... The size distributions of sheep and cow milk fat globules prior to and after homogenisation was measured by laser light scattering (Mastersizer 2000, Malvern Instruments, Malvern, U.K.) as described by Alshehab, Reis, Day, and Nitin (2019). From the size distribution, the average volume-weighted diameter (d 43 ) and the average surface-F. ...
... µm; d 4,3 of raw cow milk fat globules is approximately 3.5-4.9 µm) (Alshehab et al., 2019;Lopez, 2011). This is likely due to the milk samples were taken at the end of the milking season. ...
The regiodistribution of fatty acids (FAs) in triacylglycerols (TAGs) is highly correlated to the digestion and absorption of dietary fats. During in vitro gastric digestion, medium-long-medium/short chain triacylglycerols (MLM) showed the fastest digestibility among 105 TAG molecular species, for both raw and homogenised milk, resulting from the higher activity of gastric lipase towards medium-chain fatty acids (MCFAs) than towards long-chain fatty acids (LCFAs). After 60 min of in vitro gastric digestion, the percentage of digestion of each MLM was 16.6% to 31.2% and 12.3% to 18.6% respectively in raw sheep and cow milk, and it reached 33.4% to 45.5% and 23.0% to 38.9% respectively, after homogenisation. Sheep milk TAGs were digested faster than cow milk TAGs in raw milk (16.1% and 12.4%, respectively) as well as after homogenisation (24.1% and 20.3%, respectively). This is due to the higher percentages of MCFAs esterified on the sn-1/3 positions of sheep milk TAGs (48.3-67.3% and 11.9-51.5% respectively for sheep and cow milk prior to and after homogenisation). Homogenisation favoured TAG lipolysis due to the increased fat globule surface area; however, it did not affect lipase regiospecificity towards TAG molecular species.
... A procedure to determine the MFG size was optimized for both WPPC and bovine milk [8]. Before use, the desired volumes of frozen WPPC and bovine milk samples were gently thawed over ice at 4 • C for 3 days [50]; MFG samples (liquid and powder) were diluted with Milli-Q water in a 1:9 ratio. Diluted samples were treated with 35 mM EDTA (pH 7.0) at a 1:5 volume ratio. ...
This work investigates the composition of whey protein phospholipid concentrate (WPPC), an underutilized dairy stream, and reveals that it is a source of many bioactive compounds that can benefit the immune system and gut health. Our glycoproteomics approach uncovered that proteins derived from the milk fat globule membrane (MFGM) represent 23% of the total protein relative abundance and identified 85 N-glycans. Released sialic acid, an additional marker of glycosylation, ranged from 1.2 to 2% of the total weight. Xanthine oxidase, a glycosylated marker of MFG bioactivity, was found in high abundance and displayed higher antimicrobial activity than bovine milk, despite its similar fat and solids content. An average MFG diameter of 2.64 ± 0.01 µm was found in liquid WPPC, compared to 4.78 ± 0.13 µm in bovine milk, which likely explains the unusually high presence of glycosylated membrane-bound proteins and phospholipids, whose total fatty acids accounted for 20% of the WPPC total fatty acid pool. Free and bound oxylipins (mainly derived from linoleic acid) were also identified, together with other less abundant anti-inflammatory lipid mediators derived from eicosapentaenoic acid and docosahexaenoic acid. Our study demonstrates that WPPC represents a promising starting material for bioactive compound extraction and a functional vehicle for the delivery of small MFGs.
... It has been demonstrated that these compounds move through the fat globule membrane by a passive diffusion process. Thus, an additional amount of vitamin D can be loaded into the native fat globules by permeation to the lipid core through the membrane [72] that, in turn, protects the vitamin D against the acidic conditions of the gastric environment. Studies on gastrointestinal digestion of milk indicate that the presence of membrane fragments in the gut lumen promotes the interaction with bile [73]. ...
Vitamin D is essential in assuring bone health at all stages of life, but its non-skeletal effects are also essential: This vitamin impacts the physiology of the immune system, skeletal muscles and adipose tissue, glucose metabolism, skin, cardiovascular and reproductive systems, neuro-cognitive functions and cell division. The incidence of vitamin D deficiency is widespread worldwide, at any age, in young and healthy subjects, as well as in pregnant women and the elderly population, due to several factors, including inadequate sunlight exposure, skin pigmentation and coverage, adiposity, lifestyle and low dietary intakes. To overcome this problem, the fortification of foods that are consumed on a daily basis, such as milk, is strongly advisable. This opinion paper aims to discuss, in a multidisciplinary way, the current evidence supporting the importance of vitamin D in health and disease and the role of milk as an optimal carrier of this vitamin, to promote adequate intakes, highlighting its unique physico-chemical characteristics linked to both fat globule membrane and casein micelle structure. Moreover, it addresses the impact of industrial processing and storage of consumption milk on the stability of these structures, thus in determining vitamin D bioavailability and the achievement of adequate intakes.
Consumers are demanding more natural, healthy, and high-quality products. The addition of health-promoting substances, such as bioactive compounds, to foods can boost their therapeutic effect. However, the incorporation of bioactive substances into food products involves several technological challenges. They may have low solubility in water or poor stability in the food environment and/or during digestion, resulting in a loss of their therapeutic properties. Over recent years, the encapsulation of bioactive compounds into laboratory-engineered colloidal structures has been successful in overcoming some of these hurdles. However, several nature-assembled colloidal structures could be employed for this purpose and may offer many advantages over laboratory-engineered colloidal structures. For example, the casein micelles and milk fat globules from milk and the oil bodies from seeds were designed by nature to deliver biological material or for storage purposes. These biological functional properties make them good candidates for the encapsulation of bioactive compounds to aid in their addition into foods. This review discusses the structure and biological function of different nature-assembled carriers, preparation/isolation methods, some of the advantages and challenges in their use as bioactive compound delivery systems, and their behavior during digestion.
In recent years, there have been reports suggesting a high prevalence of low vitamin D intakes and vitamin D deficiency or inadequate vitamin D status in E urope. Coupled with growing concern about the health risks associated with low vitamin D status, this has resulted in increased interest in the topic of vitamin D from healthcare professionals, the media and the public. Adequate vitamin D status has a key role in skeletal health. Prevention of the well‐described vitamin D deficiency disorders of rickets and osteomalacia are clearly important, but there may also be an implication of low vitamin D status in bone loss, muscle weakness and falls and fragility fractures in older people, and these are highly significant public health issues in terms of morbidity, quality of life and costs to health services in E urope.
Although there is no agreement on optimal plasma levels of vitamin D , it is apparent that blood 25‐hydroxyvitamin D [25( OH ) D ] levels are often below recommended ranges for the general population and are particularly low in some subgroups of the population, such as those in institutions or who are housebound and non‐ W estern immigrants. Reported estimates of vitamin D status within different E uropean countries show large variation. However, comparison of studies across E urope is limited by their use of different methodologies. The prevalence of vitamin D deficiency [often defined as plasma 25( OH )D <25 nmol/l] may be more common in populations with a higher proportion of at‐risk groups, and/or that have low consumption of foods rich in vitamin D (naturally rich or fortified) and low use of vitamin D supplements.
The definition of an adequate or optimal vitamin D status is key in determining recommendations for a vitamin D intake that will enable satisfactory status to be maintained all year round, including the winter months. In most E uropean countries, there seems to be a shortfall in achieving current vitamin D recommendations. An exception is F inland, where dietary survey data indicate that recent national policies that include fortification and supplementation, coupled with a high habitual intake of oil‐rich fish, have resulted in an increase in vitamin D intakes, but this may not be a suitable strategy for all E uropean populations. The ongoing standardisation of measurements in vitamin D research will facilitate a stronger evidence base on which policies can be determined. These policies may include promotion of dietary recommendations, food fortification, vitamin D supplementation and judicious sun exposure, but should take into account national, cultural and dietary habits. For E uropean nations with supplementation policies, it is important that relevant parties ensure satisfactory uptake of these particularly in the most vulnerable groups of the population.
Native casein micelles were treated (incubated) with vitamin D2 at different hydrostatical pressures (0.1, 200, 400, and 600 MPa) and temperatures (10-50 °C) in order to load the vitamin. Pressure induced the release of αs-, β- and κ-casein and calcium from the micelle into the soluble phase. During the pressure stable reassembled micelles were created due to a structural rearrangement of hydrophobic interactions between the hydrophobic domains of the caseins and vitamin D2. Treatment at 600 MPa and 50 °C increased the loading of vitamin D2 per casein from 2.2 ± 0.2 μg/mg (native sample) to 10.4 ± 0.2 μg/mg. The reassembled micelles presented an average hydrodynamic diameter of 272 ± 10 nm and contained 8.1, 10.3 and 0.8 mg of α-, β- and κ-casein, respectively, per 100 mg casein.
Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives allowing for the determination of a variety of endpoints such as bioaccessibility of nutrients and non-nutrients, or digestibility of macronutrients such as lipids, proteins and carbohydrates, are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.
Vitamin D deficiency is a major public health problem worldwide in all age groups, even in those residing in countries with low latitude, where it was generally assumed that UV radiation was adequate enough to prevent this deficiency, and in industrialized countries, where vitamin D fortification has been implemented now for years. However, most countries are still lacking data, particularly population representative data, with very limited information in infants, children, adolescents and pregnant women. Since the number of recent publications is escalating, with a broadening of the geographic diversity, the objective of the present report was to conduct a more recent systematic review of global vitamin D status, with particular emphasis in at risk groups. A systematic review was conducted in PubMed/Medline in April-June 2013 to identify articles on vitamin D status worldwide published in the last 10 years in apparently healthy individuals. Only studies with vitamin D status prevalence were included. If available, the first source selected was population-based or representative samples studies. Clinical trials, case-control studies, case reports or series, reviews, validation studies, letters, editorials, or qualitative studies were excluded. A total of 103 articles were eligible and included in the present report. Maps were created for each age group, providing an updated overview of global vitamin D status. In areas with available data, the prevalence of low vitamin D status is a global problem in all age groups, in particular in girls and women from the Middle East. These maps also evidenced the regions with missing data for each specific population groups. There is striking lack of data in infants, children and adolescents worldwide, and in most countries of South America and Africa. In conclusion, vitamin D deficiency is a global public health problem in all age groups, particularly in those from the Middle East.
Lipids organisation might modulate fatty acid bioavailability leading to health implications. We determined whether the size and the interfacial composition of cow milk fat globules could affect triglycerides digestibility. Native fat globules of various sizes covered by their biological membrane (4.2 μm, large LFG 6.6 μm, small SFG 1.7 μm) or homogenised ± heat-treated (0.3 μm) were digested in gastric and duodenal conditions simulating human physiology. Lipolysis extents were calculated from the amount of free fatty acids generated, and the fatty acid composition of the products of lipolysis was determined by GC analysis. SFG were more efficiently hydrolysed than LFG by gastric (13.3 versus 5.6%), gastric plus pancreatic (62.9 versus 48.7%) and pancreatic (79.6 versus 54.7%) lipases. A higher lipid interface area with native SFG, that might increase lipases binding sites, can explain these results. However, the homogenisation, which markedly decreases fat globule size increasing consequently the lipid/water interface area, did not improve gastric (9%) or duodenal (64.5%) lipolysis probably due to an important change in globule surface composition (proteins versus phospholipids). Interestingly, the size of the milk globule (SFG and HM versus NM and LFG) controls the type of the free fatty acids generated by the human gastric lipase, palmitic versus oleic acid, suggesting a different orientation of the accessible mixed triglycerides. Moreover, the type of monoglycerides produced from SFG digestion could be less atherogenic compared to LFG. The size of fat globules governs gastric and duodenal lipolysis extent when the composition of the interfacial layer is appropriate. It might further control fatty acid bioavailability impacting on gastric emptying rate via the preferential release of oleic acid, a strong stimulator of CCK
Humans derive most vitamin D from the action of sunlight in their skin. However, in view of the current Western lifestyle with most daily activities taking place indoors, sun exposure is often not sufficient for adequate vitamin D production. For this reason, dietary intake is also of great importance. Animal foodstuffs (e.g., fish, meat, offal, egg, dairy) are the main sources for naturally occurring cholecalciferol (vitamin D-3). This paper therefore aims to provide an up-to-date overview of vitamin D-3 content in various animal foods. The focus lies on the natural vitamin D-3 content because there are many countries in which foods are not regularly fortified with vitamin D. The published data show that the highest values of vitamin D are found in fish and especially in fish liver, but offal also provides considerable amounts of vitamin D. The content in muscle meat is generally much lower. Vitamin D concentrations in egg yolks range between the values for meat and offal. If milk and dairy products are not fortified, they are normally low in vitamin D, with the exception of butter because of its high fat content. However, as recommendations for vitamin D intake have recently been increased considerably, it is difficult to cover the requirements solely by foodstuffs.
Obese individuals have more (hyperplastic) and larger (hypertrophic) adipocytes in their white adipose tissue (WAT) than normal-weight individuals. The difference in cell number emerges early in childhood, suggesting that this is a critical period for being susceptible to obesity. Breast-feeding has been shown to be protective against obesity, and we have previously shown in mice that the physical structure of lipids in human milk may contribute to this protective effect. In the present study, we investigated how differences in the physical structure of lipids in the early diet may modulate adipose tissue development. Male mice were fed a diet containing control infant milk formula (Control IMF; Danone Research) or Nuturis® (Concept IMF with large phospholipid-coated lipid droplets; Danone Research) from postnatal day (PN)16 to 42. Subsequently, mice were challenged with a moderate Western-style diet (WSD) until PN98, and body composition was monitored by dual-energy X-ray absorptiometry. Epididymal WAT was analysed for adipocyte size, number and gene expression of metabolic transcription factors. Early Concept IMF exposure reduced fat accumulation during the WSD challenge by 30 % compared with the Control IMF. It reduced adipocyte size without affecting adipocyte number in adult mice. The Concept IMF decreased the expression of PPARγ, CCAAT/enhancer-binding protein and retinoid X receptor α in WAT in adulthood, key regulators of metabolic activity. In conclusion, Concept IMF exposure in early life reduced susceptibility to obesity in adult life, by preventing adipocyte hypertrophia upon adult dietary challenge without affecting adipogenesis. These data emphasise the importance of the physical properties of dietary lipids in early life in obesity risk later in life.
Milk fat globule membranes (MFGM) were isolated from milk from cows injected intraperitoneally with dl-α-tocopherol acetate. The fatty acid composition and content, and the contents of tocopherols, retinol and β-carotene were determined and compared with the composition and content in the original cream sample. Intraperitoneal injection of 10 g dl-α-tocopherol acetate elevated the α-tocopherol content in the milk fat from 13–30 to 50–70 εg α-tocopherol/g milk fat 2–3 d after injection. The increase depended on the α-tocopherol status of the cow prior to injection. The concentrations of retinol and β-carotene in the milk fat were unchanged after the α-tocopherol injections. MFGM fatty acids made up 18–27 g/kg total fatty acids in the milk fat. However, the proportions of monounsaturated and polyunsaturated fatty acids were higher in MFGM than in total milk fat, while the proportion of saturated fatty acids was lower in MFGM (P < 0·001). Thus, the longchain polyunsaturated fatty acids in MFGM constituted 40–70 g/kg total milk fat. α-Tocopherol was the only fat-soluble vitamin detected in MFGM; γ-tocopherol, retinol and β-carotene were detected only in the cream. A significant relationship between α-tocopherol contents in cream and MFGM was found: (α-tocopherol in MFGM fatty acids) =–1652 × (1/ln(α-tocopherol in cream fatty acids)3)+ 97 (r = 0·857, P < 0·001) when the contents of α-tocopherol were expressed as εg/g fatty acid. According to this equation the upper limit for incorporation of α-tocopherol into MFGM is 97±5 εg/g MFGM fatty acids. Thus, under normal farming conditions the α-tocopherol content will be highest in MFGM. However, in cream with an α-tocopherol concentration < 15 εg/g cream fatty acids the concentration in MFGM will be lower and furthermore will decrease rapidly. The possible importance of this relationship in relation to the oxidation of milk fat is discussed.
This paper visualizes the available data on vitamin D status on a global map, examines the existing heterogeneities in vitamin D status and identifies research gaps.
A graphical illustration of global vitamin D status was developed based on a systematic review of the worldwide literature published between 1990 and 2011. Studies were eligible if they included samples of randomly selected males and females from the general population and assessed circulating 25-hydroxyvitamin D [25(OH)D] levels. Two different age categories were selected: children and adolescents (1-18 years) and adults (>18 years). Studies were chosen to represent a country based on a hierarchical set of criteria.
In total, 200 studies from 46 countries met the inclusion criteria, most coming from Europe. Forty-two of these studies (21 %) were classified as representative. In children, gaps in data were identified in large parts of Africa, Central and South America, Europe, and most of the Asia/Pacific region. In adults, there was lack of information in Central America, much of South America and Africa. Large regions were identified for which the mean 25(OH)D levels were below 50 nmol/L.
This study provides an overview of 25(OH)D levels around the globe. It reveals large gaps in information in children and adolescents and smaller but important gaps in adults. In view of the importance of vitamin D to musculoskeletal growth, development, and preservation, and of its potential importance in other tissues, we strongly encourage new research to clearly define 25(OH)D status around the world.
SummaryThis review describes the vitamin D status in different regions of the world with the objective of understanding the scope
of hypovitaminosis D and the factors related to its prevalence that may contribute to the pathogenesis of osteoporosis and
fragility fractures.
IntroductionVitamin D status has been linked to the pathogenesis of hip fractures as well as other skeletal and non-skeletal disorders.
The purpose of this review is to provide a global perspective of vitamin D status across different regions of the world and
to identify the common and significant determinants of hypovitaminosis D.
MethodsSix regions of the world were reviewed—Asia, Europe, Middle East and Africa, Latin America, North America, and Oceania—through
a survey of published literature.
ResultsThe definition of vitamin D insufficiency and deficiency, as well as assay methodology for 25-hydroxyvitamin D or 25(OH)D,
vary between studies. However, serum 25(OH)D levels below 75nmol/L are prevalent in every region studied whilst levels below
25nmol/L are most common in regions such as South Asia and the Middle East. Older age, female sex, higher latitude, winter
season, darker skin pigmentation, less sunlight exposure, dietary habits, and absence of vitamin D fortification are the main
factors that are significantly associated with lower 25(OH)D levels.
ConclusionReports from across the world indicate that hypovitaminosis D is widespread and is re-emerging as a major health problem globally.
The objective was to provide guidelines to clinicians for the evaluation, treatment, and prevention of vitamin D deficiency with an emphasis on the care of patients who are at risk for deficiency.
The Task Force was composed of a Chair, six additional experts, and a methodologist. The Task Force received no corporate funding or remuneration.
Consensus was guided by systematic reviews of evidence and discussions during several conference calls and e-mail communications. The draft prepared by the Task Force was reviewed successively by The Endocrine Society's Clinical Guidelines Subcommittee, Clinical Affairs Core Committee, and cosponsoring associations, and it was posted on The Endocrine Society web site for member review. At each stage of review, the Task Force received written comments and incorporated needed changes.
Considering that vitamin D deficiency is very common in all age groups and that few foods contain vitamin D, the Task Force recommended supplementation at suggested daily intake and tolerable upper limit levels, depending on age and clinical circumstances. The Task Force also suggested the measurement of serum 25-hydroxyvitamin D level by a reliable assay as the initial diagnostic test in patients at risk for deficiency. Treatment with either vitamin D(2) or vitamin D(3) was recommended for deficient patients. At the present time, there is not sufficient evidence to recommend screening individuals who are not at risk for deficiency or to prescribe vitamin D to attain the noncalcemic benefit for cardiovascular protection.
The adverse effects of ethanol on bacterial growth, viability, and metabolism are caused primarily by ethanol-induced leakage of the plasma membrane. This increase in membrane leakage is consistent with known biophysical properties of membranes and ethanolic solutions. The primary actions of ethanol result from colligative effects of the high molar concentrations rather than from specific interactions with receptors. The ethanol tolerance of growth in different microorganisms appears to result in large part from adaptive and evolutionary changes in cell membrane composition. Different cellular activities vary in their tolerance to ethanol. Therefore, it is essential that the aspect of cellular function under study be specifically defined and that comparisons of ethanol tolerance among systems share this common definition. Growth is typically one of the most sensitive cellular activities to inhibition by ethanol, followed by survival, or loss of reproductive ability. Glycolysis is the most resistant of these three activities. Since glycolysis is an exergonic process, a cell need not be able to grow or remain viable for glycolysis to occur.
Sheep milk has a high nutritional value and high concentrations of proteins, fats, minerals, and vitamins, as compared to the milks of other domestic species. The physicochemical and nutritional characteristics of sheep milk can be advantageous for the manufacture of products containing prebiotic ingredients and/or probiotic bacteria, which are major categories in the functional food market. Following this technological trend, this review will address the characteristics and advantages of sheep milk as a potentially functional food, as well as the development of sheep milk dairy products containing prebiotics and/or probiotics.
Vitamin D deficiency is prevalent in some populations leading to adverse health effects, and therefore there is a need to supplement functional foods and beverages with this important micronutrient. In this study, we examined the influence of the initial lipid droplet size on the in vitro bioaccessibility and in vivo absorption of vitamin D2 encapsulated in oil-in-water emulsions. Changes in particle size, charge, and microstructure were measured as vitamin-loaded lipid droplets were passed through a simulated GIT (mouth, stomach, small intestine). The in vitro studies showed that smaller lipid droplets were digested more rapidly than larger ones, thereby leading to the more rapid formation of mixed micelles in the small intestine capable of solubilizing the lipophilic vitamins. This effect may account for the highest vitamin D2 bioaccessibility being observed for the emulsions containing the smallest droplets. In contrast, the in vivo rat feeding studies suggested that the absorption of vitamin D2 was the highest for the emulsions containing the largest droplets. The poor in vitro-in vivo correlation observed in our study may have occurred for a number of reasons: the simulated GIT did not accurately model the complexity of a real GIT; the in vivo approach used did not monitor changes in vitamin levels in the blood over time. Overall, this study suggests that particle size does influence the gastrointestinal fate of encapsulated oil-soluble vitamins, but that further work is needed to establish strong correlations between in vitro and in vivo methods.
Nanostructured lipid carriers (NLCs) for encapsulating vitamin D3 (VD3), a lipophilic vitamin, were successfully fabricated by hot high pressure homogenization. The physicochemical properties of the VD3-NLCs were characterized, and the release profiles of VD3 in simulated gastrointestinal fluids were investigated. Optimum VD3-NLCs were obtained with a small diameter (132.9 nm), a high zeta potential (-41.90 mV), and a high encapsulation efficiency (85.6%). The stability of the VD3-NLCs was tested during 20 days of storage at 25 °C under a wide range of pHs. In vitro digestion in simulated gastrointestinal fluids demonstrated their capability for controlled release because the NLCs were able to remain stable and protect the VD3 in simulated stomach fluid, but released more than 90% of the VD3 in simulated intestinal fluid. Therefore, the developed NLCs are promising carriers for increasing the oral bioavailability of VD3.
In any food fortification program, the stability of added micronutrients is an important factor. Cholecalciferol or vitamin D3 is known to isomerise under various conditions, thereby making its analysis challenging. In the current study, the effects of different parameters, such as temperature, iodine, acidic conditions, and oxidation, on the isomerisation of vitamin D3 were studied using HPLC-DAD and UHPLC-MS/MS. Vitamin D3 thermally and reversibly transforms to pre-vitamin D3 type isomers. In the presence of iodine, cis/trans isomerisation of both cholecalciferol and pre-vitamin D3 takes place to form trans-vitamin D3 and tachysterol, respectively. Another isomer, isotachysterol, was formed under acidic conditions. The different rates of reaction of these products with a dienophile through the Diels-Alder reaction confirmed the formation of vitamin D3 isomerisation products. The derivatisation enhanced the ionisation efficiency of vitamin D3 and its isomers in UHPLC-MS/MS and improved the separation and fragmentation enabling sensitive detection.
The aim of the present work was to determine the fatty acid and fat-soluble vitamin composition and the season of ewe's milk production using NIR spectroscopy. 219 ewe's milk samples from different breeds and feeding regimes were taken each month over one year. Fatty acids were analyzed by gas chromatography , and retinol and a-, and c-tocopherol by liquid chromatography. The results showed that the quan-tification was more accurate for the milk dried on paper, except for vitamins. Calibration statistical descriptors on milk dried on paper were good for capric, lauric, myristic, palmitoleic, stearic and oleic acids, and acceptable for caprilic, undecanoic, 9c, 11tCLA, RCLA, PUFA, x3, x6, retinol and a-tocopherol. The equations for the discrimination of seasonality was obtained using the partial least squares discriminant analysis (PLSDA) algorithm. 93% of winter samples and 89% of summer samples were correctly classified using the NIR spectra of milk dried on paper.
Efficient delivery of bioactives remains a critical challenge due to their limited bioavailability and solubility. While many encapsulation systems are designed to modulate the digestion and release of bioactives within the human gastrointestinal tract, there is limited understanding of how engineered structures influence the delivery of bioactives. The objective of this study was to develop a real-time quantitative method to measure structural changes in emulsion interface during simulated intestinal digestion and to correlate these changes with the release of free fatty acids (FFAs). Fluorescence Resonant Energy Transfer (FRET) was used for rapid in-situ measurement of the structural changes in emulsion interface during simulated intestinal digestion. By using FRET, changes in the intermolecular spacing between the two different fluorescent probes labeled emulsifier was characterized. Changes in FRET measurements were compared with the release of FFAs. The results showed that bile salts and pancreatic lipase interacted immediately with the emulsion droplets and disrupted the emulsion interface as evidenced by reduction in FRET efficacy compared to the control. Similarly, a significant amount of FFAs was released during digestion. Moreover, addition of a second layer of polymers at emulsion interface decreased the extent of interface disruption by bile salts and pancreatic lipase and impacted the amount or rate of FFA release during digestion. These results were consistent with the lower donor/acceptor ratio of the labeled probes from the FRET result. Overall, this study provides a novel approach to analyze the dynamics of emulsion interface during digestion and their relationship with the release of FFAs.
Milk fat contains a number of components of nutritional significance. The first section of the review outlines the composition, structure and certain biochemical and physiological characteristics of these components. In recent times the nutritional image of milk fat has suffered adversely because of the association of saturated fat and cholesterol with coronary heart disease. The various elements that are used to justify this 'lipid-heart disease' hypothesis are discussed and the strength of the evidence is assessed. Contrary evidence, which is mostly overlooked in authoritative reviews, is presented. Trans fatty acid consumption is associated with an increased risk of coronary heart disease; however, the associations generally do not apply to trans acids of animal origin. These acids are mainly vaccenic and rumenic, acids that may possess anti-atherogenic properties. Other health related benefits for rumenic acid, particularly its role in the prevention of mammary tumorigenesis are outlined. Milk fat contains other potential anticancer agents such as sphingomyelin and other sphingolipids, butyric acid, 13-methyltetradecanoic acid, ether lipids and vitamin A. Pasture-derived compounds like β-carotene, β-ionone, gossypol and phytol may also help prevent cancer. Finally, the review discusses the antimicrobial action of milk fat and its role in long-chain polyunsaturated fatty acid metabolism, bone growth, ulcerogenesis, and energy metabolism.
Butter is rich in saturated fat [saturated fatty acids (SFAs)] and can increase plasma low density lipoprotein (LDL) cholesterol, which is a major risk factor for cardiovascular disease. However, compared with other dairy foods, butter is low in milk fat globule membrane (MFGM) content, which encloses the fat. We hypothesized that different dairy foods may have distinct effects on plasma lipids because of a varying content of MFGM.
We aimed to investigate whether the effects of milk fat on plasma lipids and cardiometabolic risk markers are modulated by the MFGM content.
The study was an 8-wk, single-blind, randomized, controlled isocaloric trial with 2 parallel groups including overweight men and women (n = 57 randomly assigned). For the intervention, subjects consumed 40 g milk fat/d as either whipping cream (MFGM diet) or butter oil (control diet). Intervention foods were matched for total fat, protein, carbohydrates, and calcium. Subjects were discouraged from consuming any other dairy products during the study. Plasma markers of cholesterol absorption and hepatic cholesterol metabolism were assessed together with global gene-expression analyses in peripheral blood mononuclear cells.
As expected, the control diet increased plasma lipids, whereas the MFGM diet did not [total cholesterol (±SD): +0.30 ± 0.49 compared with -0.04 ± 0.49 mmol/L, respectively (P = 0.024); LDL cholesterol: +0.36 ± 0.50 compared with +0.04 ± 0.36 mmol/L, respectively (P = 0.024); apolipoprotein B:apolipoprotein A-I ratio: +0.03 ± 0.09 compared with -0.05 ± 0.10 mmol/L, respectively (P = 0.007); and non-HDL cholesterol: +0.24 ± 0.49 compared with -0.14 ± 0.51 mmol/L, respectively (P = 0.013)]. HDL-cholesterol, triglyceride, sitosterol, lathosterol, campesterol, and proprotein convertase subtilisin/kexin type 9 plasma concentrations and fatty acid compositions did not differ between groups. Nineteen genes were differentially regulated between groups, and these genes were mostly correlated with lipid changes.
In contrast to milk fat without MFGM, milk fat enclosed by MFGM does not impair the lipoprotein profile. The mechanism is not clear although suppressed gene expression by MFGM correlated inversely with plasma lipids. The food matrix should be considered when evaluating cardiovascular aspects of different dairy foods. This trial was registered at clinicaltrials.gov as NCT01767077.
© 2015 American Society for Nutrition.
The influence of carrier oil type on the bioaccessibility of vitamin D3 encapsulated within oil-in-water nanoemulsions prepared using a natural surfactant (quillaja saponin) was studied using a simulated gastrointestinal tract (GIT) model: mouth; stomach; small intestine. The rate of free fatty acid release during lipid digestion decreased in the following order: medium chain triglycerides (MCT)>corn oil≈fish oil>orange oil>mineral oil. Conversely, the measured bioaccessibility of vitamin D3 decreased in the following order: corn oil≈fish oil>orange oil>mineral oil>MCT. These results show that carrier oil type has a considerable impact on lipid digestion and vitamin bioaccessibility, which was attributed to differences in the release of bioactives from lipid droplets, and their solubilization in mixed micelles. Nanoemulsions prepared using long chain triglycerides (corn or fish oil) were most effective at increasing vitamin bioaccessibility.
Copyright © 2015 Elsevier Ltd. All rights reserved.
• Sunscreens block the absorption of the sunlight spectrum responsible for the cutaneous synthesis of vitamin D (ultraviolet B). The present study was prompted by our observation of suppression of cutaneous vitamin D formation by a single application of sunscreening agents. We measured the index of vitamin D body store, serum 25-hydroxyvitamin D (25-OH-D) level, in 20 long-term users of p-aminobenzoic acid (PABA) and in 20 controls matched by age and exposure to sunlight. Serum 25-OH-D levels were significantly lower among long-term PABA users than among normal controls: 40.2 ± 3.2 vs 91.3 ± 6.2 nmol/L. Furthermore, vitamin D deficiency, ie, 25-OH-D levels below 20.0 nmol/L, was seen in two PABA users and in none of the controls. This preliminary study suggests that long-term use of PABA may be associated with low body stores of vitamin D in some persons.
(Arch Dermatol 1988;124:1802-1804)
The complex biochemical composition and physical structure of the milk fat globule (MFG) are presented as a basis for its paradoxical metabolic fate: MFG is a rapid conveyor of energy through its triacylglycerol (TAG) core but contains some low-digestible bioactive complex lipids and proteins, which influence lipid metabolism and contribute to intestinal and systemic health.
MFG structure modulates gastrointestinal lipolysis, postprandial lipemia and even the postprandial fate of ingested fatty acids. Proof-of-concept of the nutritional programming induced by early consumption of an emulsion biomimetic of MFG compared with a typical infant formula was published in an animal model (mice). The metabolic response to a high-fat diet during adulthood was improved following neonatal exposure to the biomimetic emulsion.
MFG TAG are tailored with a unique regiodistribution delivering in priority short to medium-chain fatty acids in gastric phase, an important amount of quickly metabolizable oleic acid and protecting palmitic acid in sn-2 position. MFG digestion may not only trigger rapid TAG and chylomicron plasma peaks with fast clearance but also the luminal release of nonhydrolysable bioactive compounds (glycosylated compounds and sphingomyelin), which contribute to intestinal and systemic health by shaping the microbiota and modulating the immune system. These bioactive compounds form self-assembled structures, protect specific micronutrients and lower cholesterol absorption. The health benefits of MFG consumption or of some of its fractions (MFGM) under specific structures are steadily being demonstrated with still much unsolved questions especially for populations with high nutritional needs (e.g. elderly, infants).
Native milk fat globule (MFG) size, pH, total fat, protein, and lactose composition in milk from individual cows was examined in autumn and spring 2012 and autumn 2013. Mean MFG diameters ranged between 2.5 and 5.7 µm. Some cows were observed to consistently produce small or large MFG throughout the sampling period, though trends were not consistent across all cows. Small-MFG milk contained more total polar lipids; however, the relative proportion of individual polar lipids did not differ with MFG size, with the exception of phosphatidylcholine, which was greater in small-MFG milk. No correlation between MFG size and proximate composition, including calculated fat yield or pH, was found. This work revealed a natural cow-to-cow variation in MFG size exists, which could potentially be exploited to improve the functionality of milk for manufacturing and some products.
Novel amphiphilic chitosan derivative of N,N-dimethylhexadecyl carboxymethyl chitosan (DCMCs) was synthesised. The physical properties of DCMCs were characterised by Fourier transform-infrared spectroscopy, nuclear magnetic resonance spectroscopy, X-ray diffraction and differential scanning calorimetry. DCMCs can form core–shell micelles with low critical micelle concentration (31 mg L−1). The core–shell micelles exhibited spherical shape with positive charge (+50.7 mV) and narrow size distribution (polydispersity index <0.5). Vitamin D3 (VD3) was initially used to load into the core–shell micelles, and the solubility of VD3 was improved with higher encapsulation efficiency (53.2%). The in vitro release processes of VD3 from the core–shell micelles were initially rapid and then followed by a sustained release. The Higuchi model was the most suitable for describing the entire release procedure. DCMCs core–shell micelles are promising carriers for VD3 and other hydrophobic bioactive food factors.
We investigated the retention of vitamin D3 and 25-hydroxyvitamin D3 in eggs, vitamin D3 in margarine, and vitamin D3 and vitamin D2 in bread. Our set-up illustrated the cooking methods usually performed in households i.e. boiling, frying in pan and oven, and baking. All experiments were performed three times independently of one another. The retention of vitamin D compounds in eggs and margarine during heat treatment in an oven for 40min at normal cooking temperature showed retention at 39-45%, while frying resulted in retention at 82-84%. Boiled eggs were found to have a similar level of retention (86-88%). For bread baked, as recommended in the recipe, the retention of vitamin D3 in rye bread at 69% was lower than the retention in wheat bread at 85%. A similar observation was made for vitamin D2, although the retention was slightly higher, 73% and 89%. No difference between retention of vitamin D3 and 25-hydroxyvitamin D3 in eggs was shown. Cooking may cause detrimental loss of vitamin D, but it depends on the actual foodstuffs and the heating process. Further research is needed to optimise cooking procedures to enhance retention of vitamin D. Vitamin D retention should be taken into account in future calculations of dietary intake of vitamin D.
The aim of this study is to update the values concerning nutritional components for sheep and goat dairy products. The bibliography examines first the main biochemical constituents of sheep and goat milk products but also the more specific components with potential nutritional impact and lastly it gathers information on the relationship between cheese and milk compositions and the impact of technologies. Since the composition of French small ruminant cheeses is not well established, with composition tables being old and lacking information, recent studies have been conducted in France to investigate the nutritional characteristics of sheep and goat milks and cheeses on a large scale. Goat milk cheese sampling was representative of French production, taking into account the variability linked to geographic origin, dairy or on-farm transformation and type of cheeses. Fresh lactic cheeses made with raw (6 samples) or pasteurised (6) milk, ripened lactic cheeses made with raw (11) or pasteurised (6) milk, spreads (4), soft ripened cheeses (6 “Chèvre Boite or “Brique” type cheeses) and 4 bulk raw milks were sampled twice in a summer–autumn period. These 86 samples were analysed for their nutritional value. The impact of the technological process was assessed with, for example, its effect on mineral and vitamin B content. With respect to sheep, 5 representative samples of milk were collected, just before cheese making, in the 3 main French traditional areas of dairy sheep production. The sampling was carried out 4 times in the year. The objective was to explore the variability of the nutritional characteristics of the original milk. The cheeses made with these milks were analysed after ripening with a double objective: to specify their nutritional content and to assess the relationship between milk and cheese content. Some preliminary results are given concerning fatty acids.
Effects of ethanol on permeability of large unilamellar vesicles (about 170 nm in diameter), composed of a dipalmitoyl phosphatidylcholine (DPPC)/cholesterol binary mixture, were studied by monitoring leakage of a fluorescent dye, calcein, entrapped in the inner aqueous phase of the vesicles. In the presence of 25 mol% cholesterol, the leakage was dramatically increased, and the permeability at 1.0 M ethanol was about eight times larger than that without ethanol and cholesterol. This effect of ethanol on the membrane permeability was similar to our previous findings concerning mixed membranes of dilauroyl phosphatidylethanolamine and DPPC (H. Komatsu and S. Okada (1996) Biochim. Biophys. Acta 1283, 73–79). It was suggested that the presence of ethanol can lead to high permeability even if the membranes are stable and have a low permeability in its absence.
The first fluorimetric method for assaying plasma 1α,25-dihydroxyvitamin D3 [1,25-(OH)2D3] is described. Lipid extracts from human plasma were successively purified by a Bond Elut NH2 column and a normal-phase HPLC column, and the 1,25-(OH)2D3 fractions obtained were fluorescence-labelled with 4-[2-(6,7-dimethoxy-4-methtyl-3-oxo-3,4-dihydroquinoxalyl)ethyl]-1,2,4-triazoline-3,5-dione (DMEQ-TAD). The fluorescent adducts of 1,25-(OH)2D3 were analyzed by HPLC on a reversed-phase column, after extensive elimination of the degradation products of excess reagents, by a Bond Elut PSA column followed by a normal-phase HPLC column. The intra- and inter-assay coefficients of variation were within 10% in both assays. The analytical recoveries of standard 1,25-(OH)2D3 added to plasma were quantitative. The present fluorimetric assay was compared with the established radioreceptor assay (RRA) used in measuring plasma 1,25-(OH)2D3 concentration. The regression analysis of the data afforded a relationship y = 1.049x−2.657 and a correlation coefficient (r) of 0.900.
It is now generally accepted that vitamin D deficiency is a worldwide health problem that affects not only musculoskeletal health but also a wide range of acute and chronic diseases. However, there remains cynicism about the lack of randomized controlled trials to support the association studies regarding the nonskeletal health benefits of vitamin D. This review was obtained by searching English-language studies published up to April 1, 2013, in PubMed, MEDLINE, and the Cochrane Central Register of Controlled Trials (search terms: vitamin D and supplementation) and focuses on recent challenges regarding the definition of vitamin D deficiency and how to achieve optimal serum 25-hydroxyvitamin D concentrations from dietary sources, supplements, and sun exposure. The effect of vitamin D on fetal programming epigenetics and gene regulation could potentially explain why vitamin D has been reported to have such wide-ranging health benefits throughout life. There is potentially a great upside to increasing the vitamin D status of children and adults worldwide for improving musculoskeletal health and reducing the risk of chronic illnesses, including some cancers, autoimmune diseases, infectious diseases, type 2 diabetes mellitus, neurocognitive disorders, and mortality.
Isotachysterol, the acid-catalyzed isomerization product of vitamin D3, produces seven previously unknown oxygenation products in a self-initiated autoxidation reaction under atmospheric oxygen in the dark at ambient temperature. They are (5R)-5,10-epoxy-9,10-secocholesta-6,8(14)-dien-3β-ol (6a), (5S)-5,10-epoxy-9,10-secocholesta-6,8(14)-dien-3β-ol (6b), (10R)-9,10-secocholesta-5,7,14-trien-3β,10-diol (7a), (10S)-9,10-secocholesta-5,7,14-trien-3β,10-diol (7b), (7R,10R)-7,10-epoxy-9,10-secocholesta-5,8(14)-dien-3β-ol (8), 5,10-epidioxyisotachysterol (9) and 3,10-epoxy-5-oxo-5,10-seco-9,10-secocholesta-6,8(14)-dien-10-ol (10). The formation of these products is explained in terms of free radical peroxidation chemistry.
Widespread poor vitamin D status in all age and gender groups in the United States (USA) and Canada increases the need for new food sources. Currently ∼ 60% of the intake of vitamin D from foods is from fortified foods in these countries. Those groups in greatest need are consuming significantly lower amounts of commonly fortified foods such as milk. Both countries allow voluntary vitamin D fortification of some other foods, although in Canada this practice is only done on a case-by-case basis. Novel approaches to vitamin D fortification of food in both countries now include "bio-addition" in which food staples are fortified through the addition of another vitamin D-rich food to animal feed during production, or manipulation of food post-harvest or pre-processing. These bio-addition approaches provide a wider range of foods containing vitamin D, and thus appeal to differing preferences, cultures and possibly economic status. An example is the post-harvest exposure of edible mushrooms to ultraviolet light. However, further research into safety and efficacy of bio-addition needs to be established in different target populations.
Isolated milk fat globules were subjected to enzyme hydrolysis by a specific protease (trypsin) and a non-specific protease (pronase E) to study the asymmetric arrangement of milk fat globule membrane (MFGM) proteins. The remaining proteins on the globules after proteolysis were resolved by two-dimensional gel electrophoresis and identified by mass spectrometry. By this proteomic approach, the results confirmed different susceptibility of the MFGM proteins to proteolysis by enzymes. Butyrophilin and adipophilin were completely digested by trypsin and by pronase E, whereas lactadherin and xanthine dehydrogenase/oxidase were almost resistant to hydrolysis by trypsin and partially attacked by pronase E. Based on our results and recent bibliographic data, an up-dated model of the organization of some MFGM proteins is proposed and discussed.
Physico-chemical characteristics of milk are related to its composition for a particular animal species. Sheep milk contains higher levels of total solids and major nutrient than goat and cow milk. Lipids in sheep and goat milk have higher physical characteristics than in cow milk, but physico-chemical indices (i.e., saponification, Reichert Meissl and Polenske values) vary between different reports. Micelle structures in goat and sheep milk differ in average diameter, hydration, and mineralization from those of cow milk. Caprine casein micelles contain more calcium and inorganic phosphorus, are less solvated, less heat stable, and lose -casein more readily than bovine casein micelles. Renneting parameters in cheese making of sheep milk are affected by physico-chemical properties, including pH, larger casein micelle, more calcium per casein weight, and other mineral contents in milk, which cause differences in coagulation time, coagulation rate, curd firmness, and amount of rennet needed. Renneting time for goat milk is shorter than for cow milk, and the weak consistency of the gel is beneficial for human digestion but decreases its cheese yield. Triacylglycerols (TAG) constitute the biggest part of milk lipids (nearly 98%), including a large number of esterified fatty acids. Sheep and goat milk also have simple lipids (diacylglycerols, monoacylglycerols, cholesterol esters), complex lipids (phospholipids), and liposoluble compounds (sterols, cholesterol esters, hydrocarbons). The average fat globule size is smallest (<3.5 m) in sheep milk followed by goat and cow milk. Five fatty acids (C10:0, C14:0, C16:0, C18:0, and C18:1) account for >75% of total fatty acids in goat and sheep milk. Levels of the metabolically valuable short and medium chain fatty acids, caproic (C6:0) (2.9%, 2.4%, 1.6%), caprylic (C8:0) (2.6%, 2.7%, 1.3%), capric (C10:0) (7.8%, 10.0%, 3.0%), and lauric (C12:0) (4.4%, 5.0%, 3.1%) are significantly higher in sheep and goat than in cow milk, respectively. Principal caseins (CN) in goat, sheep and cow milk are s1 -CN, s2 -CN, -CN and -CN. The main forms of caprine and ovine caseino-macropeptides (CMP), which are the soluble C-terminal derivatives from the action of chymosin on -casein during the milk clotting process of cheesemaking, have been identified and are a good source of antithrombotic peptides. Sheep and goat milk proteins are also important sources of bioactive angiotensin converting enzyme (ACE) inhibitory peptides and antihypertensive peptides. They can provide a non-immune disease defence and control of microbial infections. Important minor milk proteins include immunoglobulins, lactoferrin, transferrin, ferritin, proteose peptone, calmodulin (calcium binding protein), prolactin, and folate-binding protein. Non-protein nitrogen (NPN) contents of goat and human milks are higher than in cow milk. Taurine in goat and sheep milk derived from sulphur-containing amino acids has important metabolic functions as does carnitine, which is a valuable nutrient for the human neonate. Mineral and vitamin contents of goat and sheep milk are mostly higher than in cow milk.
Currently, there is a lack of clarity in the literature as to whether there is a definitive difference between the effects of vitamins D2 and D3 in the raising of serum 25-hydroxyvitamin D [25(OH)D].
The objective of this article was to report a systematic review and meta-analysis of randomized controlled trials (RCTs) that have directly compared the effects of vitamin D2 and vitamin D3 on serum 25(OH)D concentrations in humans.
The ISI Web of Knowledge (January 1966 to July 2011) database was searched electronically for all relevant studies in adults that directly compared vitamin D3 with vitamin D2. The Cochrane Clinical Trials Registry, International Standard Randomized Controlled Trials Number register, and clinicaltrials.gov were also searched for any unpublished trials.
A meta-analysis of RCTs indicated that supplementation with vitamin D3 had a significant and positive effect in the raising of serum 25(OH)D concentrations compared with the effect of vitamin D2 (P = 0.001). When the frequency of dosage administration was compared, there was a significant response for vitamin D3 when given as a bolus dose (P = 0.0002) compared with administration of vitamin D2, but the effect was lost with daily supplementation.
This meta-analysis indicates that vitamin D3 is more efficacious at raising serum 25(OH)D concentrations than is vitamin D2, and thus vitamin D3) could potentially become the preferred choice for supplementation. However, additional research is required to examine the metabolic pathways involved in oral and intramuscular administration of vitamin D and the effects across age, sex, and ethnicity, which this review was unable to verify.
Current data demonstrate that vitamin D deficiency contributes to the aetiology of at least two metabolic bone diseases, osteomalacia and osteoporosis. Osteomalacia, or rickets in children, results from a delay in mineralization and can be resolved by normalization of plasma calcium and phosphate homeostasis independently of vitamin D activity. The well characterized endocrine pathway of vitamin D metabolism and activities is solely responsible for vitamin D regulating plasma calcium and phosphate homeostasis and therefore for protecting against osteomalacia. In contrast a large body of clinical data indicate that an adequate vitamin D status as represented by the serum 25-hydroxyvitamin D concentration protects against osteoporosis by improving bone mineral density and reducing the risk of fracture. Interestingly adequate serum 1,25-dihydroxyvitamin D concentrations do not reduce the risk of fracture. In vitro human bone cell cultures and animal model studies indicate that 25-hydroxyvitamin D can be metabolised to 1,25-dihydroxyvitamin D by each of the major bone cells to activate VDR and modulate gene expression to reduce osteoblast proliferation and stimulate osteoblast and osteoclast maturation. These effects are associated with increased mineralization and decreased mineral resorption. Dietary calcium interacts with vitamin D metabolism at both the renal and bone tissue levels to direct either a catabolic action on bone through the endocrine system or an anabolic action through a bone tissue autocrine or paracrine system.
The membrane surrounding fat globules in milk, called the milk fat globule membrane (MFGM), represents a unique biophysical system. Over the last two decades, a great deal of knowledge on the intracellular origin, composition and structure of MFGM has been accumulated. In recent years, several health-beneficial components of MFGM have been identified, which consequently has led to increasing interest in developing MFGM as a food ingredient with unique functional properties and health benefits. This review focuses on current research relating to the composition and structure of MFGM, and interactions of MFGM with skim milk proteins during heat treatments. Various methods of isolating MFGM, reported in the literature, are reviewed and evaluated for their potential to produce MFGM ingredients for food applications. The functional properties of MFGM components, particularly their ability to stabilize oil-in-water emulsions and to form liposomes for the delivery of bioactive compounds, are discussed. Areas for future research are identified.
The phospholipid (PL) content was determined comparatively in the milk fat globule membrane (MFGM) and whole milk including their fatty acid profiles. The possible role of milk PLs in defence against pathogens was also addressed. The MFGM and whole milk showed a similar distribution of PL species; however, the fatty acid contents of the PL species were different. Total PL from MFGM showed a decrease in C18:0 content in parallel with an increase in C18:1 and C18:2 and very long-chain fatty acid (more than C20) content. No significant differences in the fatty acid content of phosphatidylcholine and sphingomyelin from either source were found. However, the phosphatidylethanolamine from MFGM had more C18:1 and C18:2 and less C14:0 and C16:0 than that from whole milk. A similar but less pronounced result was found for phosphatidylserine/phosphatidylinositol. Enterotoxigenic Escherichia coli strains failed to bind to PL, which had been previously separated by high-performance thin-layer chromatography.
Exposure to ultraviolet B radiation in sunlight provides the mechanism for more than 90% of the vitamin D production in most individuals. Concern has been expressed in recent years that the widespread use of sunscreens, particularly those with high sun protection factors, may lead to a significant decrease in solar-induced previtamin D(3) in the skin, resulting in a vitamin D level which is considered insufficient for protection against a wide range of diseases. In this article the published evidence to support and to question this view is presented. It is concluded that, although sunscreens can significantly reduce the production of vitamin D under very strictly controlled conditions, their normal usage does not generally result in vitamin D insufficiency.
Intestinal absorption of vitamin D-3 in physiological concentrations was studied in the live unanesthetised rat. In both the jejunum and the ileum a linear relationship was found between the absorption rate of the vitamin and its intraluminal concentration. Increasing the sodium taurocholate concentation in the perfusate above 5mM did not change ileal absorption rate but did decrease jejunal absorption rate. The vitamin's rate of absorption was raised by increases in either the hydrogen ion concentration in vivo is mediated by passive diffusion. The rate of absorption of ttion or the perfusate's flow rate. Addition of 2.5 mM fatty acids of varying chain length and degrees of saturation resulted in a decrease in the rate of vitamin D-3 absorption. These experiments indicate that vitamin D-3 absorption in vivo is mediated by passive diffusion. The rate of absorption of the vitamin is influenced by the composition of the perfusate and the thickness of the unstirred layer.
The contents of total, free, and bound vitamin B2 (B2) in bovine milk and their distribution in four separate milk fractions, including milk during the early lactation stage, were estimated. The total B2 content in whole mature milk was 179 +/- 25 micrograms/100 g (n = 16), and its distribution in the cream, whey, skim milk membrane, and casein fractions was 6, 67, 9, and 18%, respectively. The amount of flavins bound to protein in the total B2 was 13.6% in whole milk and rich in membrane fraction. The total B2 content (micrograms/100 g of milk) was higher in colostrum at 1-3 days (287 +/- 120) than in colostrum at 4-7 days (173 +/- 27), in transitional milk (182 +/- 33), and in mature milk (179 +/- 44). The bound flavin content decreased slightly as lactation progressed (20-30 micrograms/100 g), but the ratio of bound/total B2 did not vary (12-15%). Milk fat globule membrane (MFGM) contained 414 +/- 65 micrograms of B2/g of protein, most of it being bound to protein (92%). Market milks contained as much total B2 as raw whole milk, but the amount of bound form was only 2%. Guanidine HC1, urea, sodium dodecyl sulfate, pH at 3.0-3.5, delipidation, and boiling released most of the B2 bound to protein, suggesting that bound flavins bind to milk proteins by a hydrophobic linkage.
A new procedure for the isomerization of vitamin D and its metabolites is described. Vitamin D or its metabolites are dissolved in 100 microliters methanol and 10 M HC1 in 2-butanol is used as the reagent for isomerization. The isomerization reaction is carried out at 5 degrees C for 2-3 min which gives quantitative yields of isotachysterols down to 10 ng level without use of any carrier.
To understand 31P relaxation processes and hence molecular dynamics in the phospholipid multilayer it is important to measure the dependence of the 31P spin-lattice relaxation time on as many variables as the physical system allows. Such measurements of the 31P spin-lattice relaxation rate have been reported both as a function of Larmor frequency and temperature for egg phosphatidylcholine liposomes (Milburn, M.P., and K.R. Jeffrey. 1987. Biophys. J. 52:791-799). In principle, the spin-lattice relaxation rate in an anisotropic environment such as a bilayer will be a function of the angle between the bilayer normal and the magnetic field. However, the measurement of this angular dependence has not been possible because the rapid (on the time-scale of the spin-lattice relaxation rate) diffusion of the lipid molecules over the curved surface of the liposome average this dependence (Milburn, M.P., and K.R. Jeffrey. 1987. Biophys. J. 52:791-799; Brown, M.F., and J.H. Davis. 1981. Chem. Phys. Lett. 79:431-435). This paper reports the results of the measurement of the 31P spin-lattice relaxation rate as a function of this angle, beta', (the angle between the bilayer normal and the external magnetic field) using samples oriented between glass plates. These measurements were made at high field (145.7 MHz) where the spin-lattice relaxation processes are dominated by the chemical shielding interaction (Milburn, M.P., and K.R. Jeffrey. 1987. Biophys. J. 52:791-799). A model of molecular motion that includes a fast axially symmetric rotation of the phosphate group (tau i approximately 10(-9) s) and a wobble of the head group tilt with respect to this rotation axis has been used to describe both the angular dependence of the spin-lattice relaxation and the spectral anisotropy. Cholesterol is seen to have a negligible effect on the motional properties of the phospholipid phosphate segment as measured by the orientation dependence of the spin-lattice relaxation.
A model is put forward to describe the non-mediated transfer of non-electrolytes in terms of diffusion in homogeneous networks.
Ergocalciferol and cholecalciferol powders were studied at 25 and 40 degrees and at different humidities. Ergocalciferol decomposed rapidly at 25 and 40 degrees when stored in dry air. Decomposition of ergocalciferol led to the formation of products of higher polarity. Cholecalciferol was not as labile under dry conditions, but decomposed rapidly at high temperature.
Gas-liquid chromatography of vitamin D is complicated by the thermal rearrangement which occurs at the relatively high column temperatures used. Two peaks (pyro- and isopyro-) are thus obtained from every compound. A new procedure for the isomerisation of Vitamin D and its metabolites to isotachysterol derivatives, which give single peaks during gas chromatography, has been carefully evaluated. This procedure uses hydrochloric acid at 0°C in dichloroethane (dichloromethane and chloroform are equally good). Quantitative recoveries of ergocalciferol, cholecalciferol and metabolites were obtained down to levels of 100 ng. Below this level, loss by destruction occurred which could be overcome by the addition of 200 ng of carrier vitamin D. 1α-Hydroxylated cholecalciferol derivatives could not be isomerized in this way.