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The effect of supplementation wit n-3 fatty acids on the physical performance in subjects with spinal cord injury
Abstract
A global physical evaluation was performed in 21 males with spinal cord injury (SCI), at the beginning and at three and six months of omega-3 fatty acid (FA) supplementation. A significant increase in the proportion of eicosapentaenoic acid and docosahexanoic acid in plasma was observed in response to the supplementation (p<0.05). After six months of FA supplementation, strength endurance time increased from 127.7+/-19.0 s to 215.2+/-45.6 s in the right arm, and from 139+/-27.6 s to 237.7+/-48.7 s, in the left arm. The time to perform 20 repetitions of 70% maximum workload showed a reduction of 41% between the first and the third test. The time taken to cover a 90 meter long track, with a 6% slope, was reduced from 66.9+/-8.0 s to 59.3+/-6.7 s, at the end of the study (p<0.05). In conclusion, omega-3 FA supplementation could contribute to improve the functional capabilities in SCI subjects.
... 38,72 Ten studies were in individuals with complete SCI only; 37,43,44,54,56,58,63,75,78 nine studies were in motor complete SCI only; 45,46,50,67,68,70,76,79,80 five studies were in incomplete and motor incomplete SCI; 41,47,51,55,57 and 19 studies were in both complete and incomplete SCI. 39,40,42,48,49,52,53,[59][60][61][64][65][66]69,71 Six studies stated individuals must have the ability to ambulate or have full range of motion of lower limbs; 51,63,68,74,76,78 whereas, eight studies included only individuals who were wheelchair-dependent, non-ambulatoryorunabletostandwithoutawalkingaid,standingframe, or brace. 38,52,55,57,58,64,70,80 Two studies included both ambulatory and non-ambulatory participants 59,61 and 28 studiesdidnotspecifyambulatorystatus.Allstudiesprimarily included men (718/842 participants). ...
... 45,46,[65][66][67][68]74,78 Dietary interventions Five studies focused on a dietary intervention (Table 1). 42,49,53,56,71 Two studies involved daily omega-3 fatty acid supplementation (1.5 g DHA, 0.60-0.75 g EPA); 42,53 two studies delivered a weight management program involving dietary and behavioral counseling, education and exercise sessions (1-2 days/ week); 49,56 and one study involved dietary consultation (food intake recall and compliance with American Heart Association and American Dietetic Association guidelines). ...
... 49,56,71 Two studies involved supplementation and were not supervised. 42,53 Radomski et al. 56 reported 70% of participants attended >75% of sessions; adherence to the other interventions was unclear/not reported. ...
Context: Endocrine-metabolic disease (EMD) is associated with functional disability, social isolation, hospitalization and even death in individuals living with a chronic spinal cord injury (SCI). There is currently very low-quality evidence that rehabilitation interventions can reduce EMD risk during chronic SCI. Non-randomized trials and alternative study designs are excluded from traditional knowledge synthesis.
Objective: To characterize evidence from level 3–4 studies evaluating rehabilitation interventions for their effectiveness to improve EMD risk in community-dwelling adults with chronic SCI.
Methods: Systematic searches of MEDLINE PubMed, EMBASE Ovid, CINAHL, Cochrane Database of Systematic Reviews, and PsychInfo were completed. All longitudinal trials, prospective cohort, case–control studies, and case series evaluating the effectiveness of rehabilitation/therapeutic interventions to modify/associate with EMD outcomes in adults with chronic SCI were eligible. Two authors independently selected studies and abstracted data. Mean changes from baseline were reported for EMD outcomes. The Downs and Black Checklist was used to rate evidence quality.
Results: Of 489 articles identified, 44 articles (N = 842) were eligible for inclusion. Individual studies reported statistically significant effects of electrical stimulation-assisted training on lower-extremity bone outcomes, and the combined effects of exercise and dietary interventions to improve body composition and cardiometabolic biomarkers (lipid profiles, glucose regulation). In contrast, there were also reports of no clinically important changes in EMD outcomes, suggesting lower quality evidence (study bias, inconsistent findings).
Conclusion: Longitudinal multicentre pragmatic studies involving longer-term exercise and dietary intervention and follow-up periods are needed to fully understand the impact of these rehabilitation approaches to mitigate EMD risk. Our broad evaluation of prospective cohort and case–control studies provides new perspectives on alternative study designs, a multi-impairment paradigm approach of studying EMD outcomes, and knowledge gaps related to SCI rehabilitation.
... Supplementation with EPA and DHA may improve VO2max and aerobic performance. Javierre et al. (2006) conducted a study to determine whether omega-3 fatty acid supplementation may contribute to improved muscle strength and endurance capacity in persons with SCI. Twenty-one males, 18 with paraplegia and 3 with tetraplegia, underwent global physical evaluations at the beginning of, at 3 months and 6 months of omega-3 fatty acid supplementation. ...
... There is level 4 evidence from one pre-post study (Javierre et al., 2006) ...
... Additionally, n-3 PUFA can decrease the synthesis of the eicosanoid thromboxane A₂, thereby increasing the risk of bleeding [188]. However, this was not generally observed in a randomized clinical trial of fish oil supplementation [189]. ...
Human melanoma is a highly aggressive malignant tumor originating from epidermal melanocytes, characterized by intrinsic resistance to apoptosis and the reprogramming of proliferation and survival pathways during progression, leading to high morbidity and mortality rates. This malignancy displays a marked propensity for metastasis and often exhibits poor responsiveness to conventional therapies. Fatty acids, such as n-3 polyunsaturated fatty acids (PUFAs) docosahexaenoic and eicosapentaenoic acids, exert various physiological effects on melanoma, with increasing evidence highlighting the anti-tumorigenic, anti-inflammatory, and immunomodulatory properties. Additionally, n-3 PUFAs have demonstrated their ability to inhibit cancer metastatic dissemination. In the context of cancer treatment, n-3 PUFAs have been investigated in conjunction with chemotherapy as a potential strategy to mitigate severe chemotherapy-induced side effects, enhance treatment efficacy and improve safety profiles, while also enhancing the responsiveness of cancer cells to chemotherapy. Furthermore, dietary intake of n-3 PUFAs has been associated with numerous health benefits, including a decreased risk and improved prognosis in conditions such as heart disease, autoimmune disorders, depression and mood disorders, among others. However, the specific mechanisms underlying their anti-melanoma effects and outcomes remain controversial, particularly when comparing findings from in vivo or in vitro experimental studies to those from human trials. Thus, the objective of this review is to present data supporting the potential role of n-3 PUFA supplementation as a novel complementary approach in the treatment of malignant cancers such as melanoma.
... It translates into lower tolerance of training loads and poorer physical training performance [47]. In the study of Javierre et al., an attempt was made to evaluate the effect of ω-3 fatty acid supplementation at a dose of 1.5 g DHA and 0.6 g EPA with the additional supplementation of 9 mg alpha-tocopherol only the increase in training time in subjects after SCI [48]. A group of 21 men (n = 21) at different periods after SCI (mean 8.5 years) and different ages (mean 34 years) and with different severity of injury assessed according to the American Spinal Injury Association (ASIA) impairment scale received ω-3 fatty acid supplementation during a 6 month improvement program. ...
Omega-3 fatty acids constitute a group of fatty acids with anti-inflammatory and preventive effects against various diseases. Studies in animal models have demonstrated the preventive and therapeutic effects of omega-3 fatty acids after spinal cord injury (SCI) in reducing inflammatory reactions and promoting neuroregeneration. However, studies on the efficacy of omega-3 fatty acids in treatment and prevention after SCI seem to be questionable. This study evaluates potential reasons for omega-3 fatty acid therapy oversight in populations after SCI. Therefore, some of the reasons could cover heterogeneous patient groups in size, level of injury, quality of life assessment, time since injury, no single standardised dose, various follow-up durations and metabolic changes, often insufficient to record. Due to the difficulty of collecting cases for the study, especially in the acute phase after SCI, multicenter, coordinated studies are needed to establish the effects of omega-3 fatty acids on treatment, recovery, and disease prevention in patients after SCI. Although the present results of such studies are still inconclusive, the failure to exploit the potential properties of omega-3 fatty acids in the treatment of patients with SCI solely due to methodological difficulties should be considered a potential waste.
... It translates into lower tolerance of training loads and poorer physical training performance [47]. In the study of Javierre et al., an attempt was made to evaluate the effect of ω-3 fatty acid supplementation at a dose of 1.5 g DHA and 0.6 g EPA with the additional supplementation of 9 mg alpha-tocopherol only the increase in training time in subjects after SCI [48]. A group of 21 men (n = 21) at different periods after SCI (mean 8.5 years) and different ages (mean 34 years) and with different severity of injury assessed according to the American Spinal Injury Association (ASIA) impairment scale received ω-3 fatty acid supplementation during a 6 month improvement program. ...
Omega-3 fatty acids constitute a group of fatty acids with anti-inflammatory and preventive effects against various diseases. Studies in animal models have demonstrated the preventive and therapeutic effects of omega-3 fatty acids after spinal cord injury (SCI) in reducing inflammatory reactions and promoting neuroregeneration. However, studies on the efficacy of omega-3 fatty acids in treatment and prevention after SCI seem to be questionable. This study evaluates potential reasons for omega-3 fatty acid therapy oversight in populations after SCI. Therefore, some of the reasons could cover heterogeneous patient groups in size, level of injury, quality of life assessment, time since injury, no single standardised dose, various follow-up durations and metabolic changes, often insufficient to record. Due to the difficulty of collecting cases for the study, especially in the acute phase after SCI, multicenter, coordinated studies are needed to establish the effects of omega-3 fatty acids on treatment, recovery, and disease prevention in patients after SCI. Although the present results of such studies are still inconclusive, the failure to exploit the potential properties of omega-3 fatty acids in the treatment of patients with SCI solely due to methodological difficulties should be considered a potential waste.
... 212,213 Taking advantage of this broad use, early clinical assessment of patients with chronic SCI at different injury levels has revealed omega-3 supplementation is safe and feasible, but the studies did not demonstrate any motor function improvement, although the timing of the intervention seems to be important for potential effects to occur. [214][215][216] Curiously, in a recent study also conducted with patients with chronic SCI, researchers showed that changing the dietary inflammatory pattern could be a way to tackle peripheral inflammation, which is commonly present in patients with SCI. 217 Functions and mechanisms of omega-3 in SCI The use of omega-3 PUFA as a neuroprotective substance arose from evidence demonstrating that DHA incorporation in cell membranes limited apoptosis in neurons in a mechanism dependent on protein kinase B activation. ...
Spinal cord injury (SCI) is a debilitating condition that leads to motor, sensory, and autonomic impairments. Its intrinsic pathophysiological complexity has hindered the establishment of effective treatments for decades. Nutritional interventions (NIs) for SCI have been proposed as a route to circumvent some of the problems associated with this condition. Results obtained in animal models point to a more holistic effect, rather than to specific modulation, of several relevant SCI pathophysiological processes. Indeed, published data have shown NI improves energetic imbalance, oxidative damage, and inflammation, which are promoters of improved proteostasis and neurotrophic signaling, leading ultimately to neuroprotection and neuroplasticity. This review focuses on the most well-documented Nis. The mechanistic implications and their translational potential for SCI are discussed.
... These include a teenager with a severe TBI sustained in an automobile accident and a 26 year-old with brain injury induced by the combination of hypoxia, dehydration, toxic gases, and rhabdomyolosis resulting from a mining accident (Roberts et al. 2008;Lewis et al. 2013). A clinical trial in patients with spinal cord injury indicated improved functional capabilities in individuals treated with omega-3 PUFA (1.5 g·DHA/day and 0.6 g EPA/day) for 6 months (Javierre et al. 2006), although another study found no effect after 14 months of treatment with DHA (435 mg/day) and EPA (65 mg/day) (Norouzi Javidan et al. 2014). Of particular importance in TBI, no increases in intra-or postoperative bleeding complications were detected in spinal cord injury patients treated with omega-3 PUFA (Kepler et al. 2012). ...
... LC-PUFA or fish oil treatment has been beneficial in treating adult neural injuries in several models, including humans [24][25][26][42][43][44]. This study investigated the effects of oral fish oil treatment in 17-day old rats, which are comparable to human toddlers with respect to motor development [45,46], on the functional and molecular outcomes of TBI. ...
The effects of an oral fish oil treatment regimen on sensorimotor, blood-brain barrier, and biochemical outcomes of traumatic brain injury (TBI) were investigated in a juvenile rat model. Seventeen-day old Long-Evans rats were given a 15mL/kg fish oil (2.01g/kg EPA, 1.34g/kg DHA) or soybean oil dose via oral gavage 30min prior to being subjected to a controlled cortical impact injury or sham surgery, followed by daily doses for seven days. Fish oil treatment resulted in less severe hindlimb deficits after TBI as assessed with the beam walk test, decreased cerebral IgG infiltration, and decreased TBI-induced expression of the Mmp9 gene one day after injury. These results indicate that fish oil improved functional outcome after TBI resulting, at least in part from decreased disruption of the blood-brain barrier through a mechanism that includes attenuation of TBI-induced expression of Mmp9.
... N-3 PUFAs and their metabolites have anti-inflammatory effects in neural and non-neural tissues [23]. In animal models, administration of DHA or consuming a diet high in n-3 PUFAs, has been beneficial in various types of neuronal injuries including TBI [24][25][26][27][28], although a worsened outcome has also been reported [29]. However, very little is known about what role endogenous brain DHA has in neuroprotection after TBI. ...
The effects of dietary modulation of brain DHA content on outcomes after TBI were examined in a juvenile rat model. Long-Evans rats with normal or diet-induced decreases in brain DHA were subjected to a controlled cortical impact or sham surgery on postnatal day 17. Rats with the greatest decreases in brain DHA had the poorest sensorimotor outcomes after TBI. Ccl2, Gfap, and Mmp 9 mRNA levels, and MMP-2 and -9 enzymatic activities were increased after TBI regardless of brain DHA level. Lesion volume was not affected by brain DHA level. In contrast, TBI-induced Timp1 expression was lower in rats on the Deficient diet and correlated with brain DHA level. These data suggest that decreased brain DHA content contributes to poorer sensorimotor outcomes after TBI through a mechanism involving modulation of Timp1 expression.
... Les pronostics de récupération sur le plan moteur et la diminution des lésions au niveau histologique seraient même liés à une administration de cet acide gras non seulement en phase aiguë mais aussi en complément alimentaire pendant les six semaines suivant le traumatisme. Des essais cliniques, proposant une supplémentation à base d'EPA ou de DHA objectiveraient une augmentation de la force motrice chez des blessés médullaires (Javierre et al., 2006), sans modifier leur statut lipidique sanguin (Javierre et al., 2005). ...
It has been shown that the onset of a central nervous system lesion in the rat results in morphological modifications of the peripheral nerves and the underlying neuromuscular junctions, without suggesting a functional correlation between recuperation of motor functions and sublesional metabolic activity. Using double lesion localization (T2 and T6) in a spinal rat model has nevertheless pointed out the functional importance of the T2-T6 metameric interval in the reinnervation phenomena observed, raising the problem of spinal generation in locomotor movements. Motivated by electrophysiological data that have given support to the concept of an anatomic substrate for these intramedullary rhythm generators, we attempted to establish a relation between the functional recuperation possible after a central nervous system lesion and modifications within the metabolism of the underlying neuromuscular system. We notably focused on Na/K-ATPase, whose crucial role in neuromuscular transmission has been evidenced. This paper proposes to demonstrate the involvement in the mechanisms of metabolic regulation after trans-synaptic denervation, i.e., a central nervous system lesion. Our study includes the Na/K-ATPase activity analysis on the sublesional peripheral nerve and the combined analysis of the expression of different RNA messengers within the corresponding muscle groups. We have also investigated the spatiotemporal organization of the compensating processes of the nerves underlying the lesion using magnetic resonance spectroscopy.
Objectives
Individuals with spinal cord injury are at risk of secondary health conditions (SHC) that develop as a consequence of autonomic dysfunction, prolonged oxidative stress and inflammation, and physical inactivity coupled with inadequate energy and nutritional intake. SHC can be debilitating and even life-threatening, and its prevention remains one of the major challenges in the continuum of medical care of aging SCI population. An unhealthy diet is a major driver of inflammation, oxidative stress, and unfavourable metabolic status and may be a practical preventive target to tackle increased SHC risk post-injury.
Aims
To provide a catalogue of dietary interventions beneficial in prevention of SHC among individuals with SCI by conducting a systematic review of the literature on dietary interventions and dietary supplementation in promoting health and well-being after the injury. In addition, we aimed to provide a summary of observational studies exploring the association between habitual diet (macro- and micronutrients intake and dietary patterns) and health patterns following the injury.
Method
This review was registered at PROSPERO (University of York) with registration number CRD42022373773. Four medical databases (EMBASE.com, MEDLINE [Ovid], Cochrane CENTRAL, and Web of Science Core Collection) and Google Scholar were searched from inception until 11th July 2022. Studies were included if they were clinical trials or observational studies conducted in adult individuals with SCI and provided information of interest. Based on strength of the study design and risk of bias assessment (using the NIH tool), we classified studies from Level 1 (most reliable studies) to Level 4 (least reliable studies).
Results
Of 12,313 unique citations, 47 articles (based on 43 original studies) comprising 32 interventional (22 RCTs, 3 NRCT, and 7 pre-post studies) and 11 observational studies (2 cohort studies, 2 case-control, 1 post-intervention follow-up study, and 6 cross-sectional studies) were included in the present systematic review. Twenty studies (46.5%) were classified as Level 1 or 2, indicating high/moderate methodological quality. Based on those studies, dietary strategies including high protein diet, intermittent fasting, balanced diet in combination with physical conditioning and electrical stimulation, and dietary supplementation including alpha-lipoic acid, creatine, vitamin D, and cranberry-derived supplements and probiotics were mapped as the most promising in prevention of SHC among individuals with SCI.
Conclusions
To develop timely and effective preventive strategies targeting major SHC (e.g., cardiometabolic diseases, urinary tract infections) in SCI, further research is warranted to confirm the effectiveness of dietary strategies/interventions identified through the current systematic review of the literature.
Objective: To identify the tools used to evaluate muscle strength in subjects with spinal cord injury in both clinical practice and scientific research. Methods: Initially, the literature review was carried out to identify the tools used in scientific research. The search was conducted in the following databases: Virtual Health Library (VHL), Pedro, and PubMed. Studies published between 1990 and 2016 were considered and selected, depicting an evaluation of muscle strength as an endpoint or for characterization of the sample. Next, a survey was carried out with physiotherapists to identify the instruments used for evaluation in clinical practice, and the degree of satisfaction of professionals with respect to them. Results: 495 studies were found; 93 were included for qualitative evaluation. In the studies, we verified the use of manual muscle test with different graduation systems, isokinetic dynamometer, hand-held dynamometer, and manual dynamometer. In clinical practice, the manual muscle test using the motor score recommended by the American Spinal Cord Injury Association was the most used method, despite the limitations highlighted by the physiotherapists interviewed. Conclusion: In scientific research, there is great variation in the methods and tools used to evaluate muscle strength in individuals with spinal cord injury, differently from clinical practice. The tools available and currently used have important limitations, which were highlighted by the professionals interviewed. No instrument depicts direct relationship of muscle strength and functionality of the subject. There is no consensus as to the best method for assessing muscle strength in spinal cord injury, and new instruments are needed that are specific for use in this population.
Background:
Individuals with spinal cord injury (SCI) consume more dietary supplements than the general population. However, there is limited information regarding the clinical effectiveness of dietary supplements in SCI population.
Objective:
To systematically review the effectiveness of dietary supplements for the prevention or treatment of health-related conditions associated with SCI.
Methods:
Randomized or non-randomized controlled clinical trials were selected, comparing the effect of any dose and form of a dietary supplement (defined by the Dietary Supplement Health and Education Act), with either no treatment, placebo, or other medication. Data Sources included the Cochrane Database, DARE, LILACS, CINAHL, EMBASE, MEDLINE, OTSeeker, PEDro, PsycINFO, SpeechBITE, ScienceDirect, Scopus, clinicaltrials.gov, Google Scholar, and OpenGrey. Two reviewers independently classified articles from January 1970 through October 2015, and 18 articles were selected.
Results:
Due to the heterogeneity of outcome measures across studies, a meta-analysis was not conducted. However, high-quality evidence showed that cranberry supplementation is not effective for prevention of urinary tract infections (UTIs) in SCI. Moderate-quality evidence supported a beneficial effect of vitamin D, alpha-lipoic acid, and omega-3 supplementation, although replication of results is needed. There were conflicting results for the effect of creatine supplementation on improvement of motor outcomes. Low-quality evidence does not permit assessment of the effectiveness of melatonin, whey protein, vitamin C, and Chinese herb in SCI.
Conclusions:
There is sufficient data suggesting that cranberry supplementation is ineffective for prevention of UTIs in individuals with SCI. There is insufficient data to support or refute the use of any other dietary supplement in individuals with SCI.
Objective: To study the differences in respiratory responses to exercise in environmental conditions similar to the practice of winter sports among physically active and healthy men with and without spinal cord injury (SCI). Methods: 24 healthy, physically active volunteers, 12 with SCI and the other 12 without SCI. Each subject performed three maximal exercise tests monitoring ventilatory parameters, but changing environmental circumstances: at sea level and 22-24°C, at 3,000 meters simulated high and 22-24°C, and at simulated 3,000 meters and 5-6°C. Results: When comparing the values observed in simulated altitude tests regarding the level sea, there was a significant increase of the values of oxygen uptake and VCO2 production. This increase was not accompanied by changes in ventilation, respiratory rate or tidal volume. In parallel, fractional exhaled O2 and CO2, the respiratory equivalent for O2 and CO2 and end-tidal O2 and end-tidal CO2 showed statistically significant changes. Conclusions: In a simulated altitude of 3,000 meters, an intensive effort produce significant changes with higher oxygen demand that do not vary substantially with the cold.
Traumatic spinal cord injury (SCI) triggers a robust inflammatory response consisting of activated neutrophils, macrophages, astrocytes, T cells and B cells. The magnitude and timing of the immune response vary depending upon the spinal level of injury (thoracic vs. cervical), injury severity, species and strain, age at the time of injury, and mode of injury (i.e. contusion, compression or ischemic). Regardless of these factors, however, these immune responses persist after SCI and contribute to pathological and reparative processes. Throughout this chapter, we will discuss the role that individual aspects of the innate and adaptive immune responses may be playing in repair or pathology after SCI. Where appropriate, current clinical therapies targeting these immune response will be highlighted.
It has been shown that the onset of a central nervous system lesion in the rat results in morphological modifications of the peripheral nerves and the underlying neuromuscular junctions, without suggesting a functional correlation between recuperation of motor functions and sublesional metabolic activity. Using double lesion localization (T2 and T6) in a spinal rat model has nevertheless pointed out the functional importance of the T2–T6 metameric interval in the reinnervation phenomena observed, raising the problem of spinal generation in locomotor movements. Motivated by electrophysiological data that have given support to the concept of an anatomic substrate for these intramedullary rhythm generators, we attempted to establish a relation between the functional recuperation possible after a central nervous system lesion and modifications within the metabolism of the underlying neuromuscular system. We notably focused on Na/K-ATPase, whose crucial role in neuromuscular transmission has been evidenced. This paper proposes to demonstrate the involvement in the mechanisms of metabolic regulation after trans-synaptic denervation, i.e., a central nervous system lesion. Our study includes the Na/K-ATPase activity analysis on the sublesional peripheral nerve and the combined analysis of the expression of different RNA messengers within the corresponding muscle groups. We have also investigated the spatiotemporal organization of the compensating processes of the nerves underlying the lesion using magnetic resonance spectroscopy.
A diet including 2-3 portions of fatty fish per week, which corresponds to the intake of 1.25 g EPA (20:5n-3) + DHA (22:6n-3) per day, has been officially recommended on the basis of epidemiological findings showing a beneficial role of these n-3 long-chain PUFA in the prevention of cardiovascular and inflammatory diseases. The parent fatty acid ALA (18:3n-3), found in vegetable oils such as flaxseed or rapeseed oil, is used by the human organism partly as a source of energy, partly as a precursor of the metabolites, but the degree of conversion appears to be unreliable and restricted. More specifically, most studies in humans have shown that whereas a certain, though restricted, conversion of high doses of ALA to EPA occurs, conversion to DHA is severely restricted. The use of ALA labelled with radioisotopes suggested that with a background diet high in saturated fat conversion to long-chain metabolites is approximately 6% for EPA and 3.8% for DHA. With a diet rich in n-6 PUFA, conversion is reduced by 40 to 50%. It is thus reasonable to observe an n-6/n-3 PUFA ratio not exceeding 4-6. Restricted conversion to DHA may be critical since evidence has been increasing that this long-chain metabolite has an autonomous function, e.g. in the brain, retina and spermatozoa where it is the most prominent fatty acid. In neonates deficiency is associated with visual impairment, abnormalities in the electroretinogram and delayed cognitive development. In adults the potential role of DHA in neurological function still needs to be investigated in depth. Regarding cardiovascular risk factors DHA has been shown to reduce triglyceride concentrations. These findings indicate that future attention will have to focus on the adequate provision of DHA which can reliably be achieved only with the supply of the preformed long-chain metabolite.
The present study examined the effects of a 3-week fish-oil supplementation (6 g/d) on the rate of plasma glucose disappearance (Rd glucose), hepatic glucose production (HGP), carbohydrate oxidation and lipid oxidation during exercise. Six untrained males (23+/-1 years; 67.6+/-2.7 kg) performed two 90 min cycling exercise sessions at 60 % of maximal O2 output separated by 20 d. During the 20 d before the first test, they ingested 6 g olive oil/d, then 6 g fish oil/d during the 20 d before the second test. Plasma glucose fluxes and lipolysis were traced using 6,6-[(2)H2]glucose and 1,1,2,3,3-[(2)H5]glycerol respectively. Substrates oxidation was obtained from indirect calorimetry. At rest HGP and the Rd glucose were similar after olive oil and fish oil (1.83 (SE 0.05) v. 1.67 (SE 0.11) mg/kg per min). During exercise, fish oil reduced the stimulation of both the Rd glucose (5.06 (SE 0.23) v. 6.37 (SE 0.12) mg/kg per min; P<0.05) and HGP (4.88 (SE 0.24) v. 5.91 (SE 0.21) mg/kg per min; P<0.05). Fish oil also reduced glucose metabolic clearance rate (6.93 (SE 0.29) v. 8.30 (SE 0.57) ml/min). Carbohydrate oxidation tended to be less stimulated by exercise after fish oil than after olive oil (12.09 (SE 0.60) v. 13.86 (se 1.11) mg/kg per min; NS). Lipid oxidation tended to be more stimulated by exercise after fish oil (7.34 (SE 0.45) v. 6.85 (SE 0.17) mg/kg per min; NS). Glycaemia, lactataemia, insulinaemia and glucagonaemia were similarly affected by exercise after fish oil and olive oil. Lipolysis at rest was similar after fish oil and olive oil (2.92 (SE 0.42) v. 2.94 (SE 0.28) micromol/kg per min) and similarly stimulated by exercise (6.42 (SE 0.75) v. 6.77 (SE 0.72) micromol/kg per min). It is concluded that fish oil reduced the Rd glucose by 26 % by reducing glucose metabolic clearance rate, possibly by facilitating fat oxidation, and reduced HGP by 21%, possibly by a feedback mechanism.
Study design:
A prospective study during a diet modification.
Objective:
To observe the evolution of the plasma lipid profile in a group of spinal cord injury (SCI) patients given a supplement of a mixture of docosahexanoic acid (DHA) and eicosapentaenoic acid (EPA).
Setting:
Department of Physiological Sciences II, Medical School of the University of Barcelona and Guttmann Institut of Badalona, Barcelona, Spain.
Methods:
A total of 19 adult males with SCI, 17 with paraplegia and two with tetraplegia, were given a daily supplement of 1.5 g of DHA and 0.75 g of EPA for 6 months. Determination of plasma values of DHA, EPA, total cholesterol, HDL-c, LDL-c, VLDL-c, triglycerides, and glucose was performed before supplementation and at 3 and 6 months of supplementation.
Results:
A statistically significant increase in the plasma concentration of EPA (F=30.556, P<0.05) and DHA (F=106.6, P<0.05) was observed after 3 and 6 months of supplementation. However, there were no observable differences in the plasma concentration of total-cholesterol, HDL-c, LDL-c, VLDL-c, and triglycerides during the study.
Conclusion:
DHA-EPA supplementation for 6 months does not modify the glycemic and lipid plasmatic levels in SCI patients. Despite its absence of effect on the serum lipid profile, n-3 fatty acids may induce beneficial cardiovascular effects in this population.
In a randomized, placebo-controlled study the effect of 10 weeks of supplementation with either 5.2 g of a concentrated fish oil triglyceride (Triomar™) enriched in omega-3 fatty acids (1.60 g/day EPA and 1.04 g/day DHA) or 5.2 g corn oil (serving as placebo) on maximal aerobic power, anaerobic threshold and running performance was assessed in 28 well-trained male soccer players (18–35 years). Supplements were given as 650-mg capsules. Capsule assignment was randomized to one omega-3 group (n=15), given eight Triomar™ capsules per day, and one placebo group (n=13), given eight capsules of corn oil per day. During the 10-week supplementation period the subjects maintained their usual diets and training regimes. Red blood cell (RBC) osmotic fragility, triglycerides and fatty acid composition in plasma were assessed before and after the supplementation period. The pre- and post-supplementation tests of maximal aerobic power, anaerobic power and running performance showed no significant difference between the two groups. Subjects in the omega-3 group had significantly reduced plasma triglycerides, rised EPA (175%) and DHA (40%) in the total lipid fraction of plasma after supplementation. RBC osmotic fragility did not change. In conclusion, the results do not support the hypothesis that endurance athletes can improve maximal aerobic performance by omega 3-fatty acid supplementation.
The UK dietary guidelines for cardiovascular disease acknowledge the importance of long-chain omega-3 polyunsaturated fatty acids (PUFA) – a component of fish oils – in reducing heart disease risk. At the time, it was recommended that the average n-3 PUFA intake should be increased from 0.1 to 0.2 g day−1. However, since the publication of these guidelines, a plethora of evidence relating to the beneficial effects of n-3 PUFAs, in areas other than heart disease, has emerged. The majority of intervention studies, which found associations between various conditions and the intake of fish oils or their derivatives, used n-3 intakes well above the 0.2 g day−1 recommended by Committee on Medical Aspects of Food Policy (COMA). Furthermore, in 2004, the Food Standards Agency changed its advice on oil-rich fish creating a discrepancy between the levels of n-3 PUFA implied by the new advice and the 1994 COMA guideline. This review will examine published evidence from observational and intervention studies relating to the health effects of n-3 PUFAs, and discuss whether the current UK recommendation for long-chain n-3 PUFA needs to be revisited.
Repeated administration of highly purified eicosapentaenoic acid (as ethyl ester) resulted in a decrease in plasma triglycerides and high density lipoprotein (HDL) cholesterol. This was accompanied by a stimulation in the activities of carnitine palmitoyltransferase, fatty acyl-CoA oxidase and peroxisomal beta-oxidation in the liver. The results suggest that the triglyceride-lowering effect observed with eicosapentaenoic acid may be due to a reduced supply of fatty acids for hepatic triglyceride synthesis because of increased fatty acid oxidation. Eicosapentaenoic acid feeding marginally affected the triglyceride content of heart and mitochondrial and peroxisomal enzyme activities.
The effects of fish oil supplementation and exercise were investigated in healthy, previously sedentary males, ages 19-34. Thirty-two subjects were assigned to four groups: control (C), fish (F), exercise (E), fish and exercise (FE). The fish groups consumed 4 g.d-1 of omega-3 fatty acids. The exercise groups performed aerobic exercise for one hour three per week. The study was conducted for 10 weeks with pre and post values obtained for cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, maximal oxygen consumption (VO2max), ventilatory anaerobic threshold (VAT), percent body fat, and dietary composition of macronutrients and polyunsaturated to saturated fat (P:S) ratio. No significant differences were noted between groups for any of the blood lipid values, percent body fat or dietary variables. VO2max and VAT did exhibit significant changes among groups. VO2max was greater for the exercise groups (E, FE) as compared to the control group (p less than 0.05). E, but not FE, was significantly greater than F. VAT was significantly greater in F, E, and FE as compared to controls, however the control's VAT decreased slightly. The slight improvement, although statistically non-significant, in VO2max and VAT by the F group requires further study. This data indicates an improvement in aerobic metabolism from aerobic exercise, alone or in combination with fish oil, compared to controls.
Because both aerobic exercise and fish oil ingestion have been shown to decrease plasma lipids, we examined the effects of combining these modalities in hyperlipidemic subjects. Thirty-four subjects were randomly assigned to one of four groups as follows: fish oil and exercise (FE), N = 7, 50 ml of oil daily and 3 d.wk-1 of aerobic exercise; fish oil (F), N = 7, 50 ml of oil daily; corn oil (CN), N = 10, 50 ml of oil daily; and control (C), N = 10. Blood samples were drawn at baseline and at the end of 4, 8, and 12 wk. The FE and F groups showed significantly lower triglycerides with respect to treatment as compared to the CN and C groups. The FE, F, and CN groups exhibited lower total cholesterol values than the control group but were not different from each other. HDL cholesterol was significantly increased after treatment in the FE and F groups as compared to the CN and C groups. Serum apo-B, LDL cholesterol, and LDL protein decreased significantly in the FE group but not the F group from baseline to 12 wk. VO2max increased and percent fat decreased only in the FE group. In conclusion, aerobic exercise improved the effects of fish oil on LDL cholesterol and apo-B and improved fitness and body composition in hyperlipidemic subjects.
Key enzymes involved in oxidation and esterification of long-chain fatty acids were investigated in male rats fed different types and amounts of oil in their diet. A diet with 20% (w/w) fish oil, partially hydrogenated fish oil (PHFO) and partially hydrogenated soybean oil (PHSO) was shown to stimulate the mitochondrial and microsomal palmitoyl-CoA synthetase activity (EC 6.2.1.3) compared to soybean oil-fed animals after 1 week of feeding. Rapeseed oil had no effect. Partially hydrogenated oils in the diet resulted in significantly higher levels of mitochondrial glycerophosphate acyltransferase compared to unhydrogenated oils in the diet. Rats fed 20% (w/w) rapeseed oil had a decreased activity of this mitochondrial enzyme, whereas the microsomal glycerophosphate acyltransferase activity was stimulated to a comparable extent with 20% (w/w) rapeseed oil, fish oil or PHFO in the diet. Increasing the amount of PHFO (from 5 to 25% (w/w)) in the diet for 3 days led to increased mitochondrial and microsomal palmitoyl-CoA synthetase and microsomal glycerophosphate acyltransferase activities with 5% of this oil in the diet. The mitochondrial glycerophosphate acyltransferase was only marginally affected by increasing the oil dose. Administration of 20% (w/w) PHFO increased rapidly the mitochondrial and microsomal palmitoyl-CoA synthetase, carnitine palmitoyltransferase and microsomal glycerophosphate acyltransferase activities almost to their maximum value within 36 h. In contrast, the glycerophosphate acyltransferase and palmitoyl-CoA hydrolase (EC 3.1.2.2) activities of the mitochondrial fraction and the peroxisomal beta-oxidation reached their maximum activities after administration of the dietary oil for 6.5 days. This sequence of enzyme changes (a) is in accordance with the proposal that an increased cellular level of long-chain acyl-CoA species act as metabolic messages for induction of peroxisomal beta-oxidation and palmitoyl-CoA hydrolase, i.e., these enzymes are regulated by a substrate-induced mechanism, and (b) indicates that, with PHFO, a greater part of the activated fatty acids are directed from triacylglycerol esterification and hydrolysis towards oxidation in the mitochondria. It is also conceivable that the mitochondrial beta-oxidation is proceeding before the enhancement of peroxisomal beta-oxidation.
Two hand rim propelled wheelchairs, a daily-use (active) wheelchair (R) and a marathon sports wheelchair (S), were compared to a three-wheeled crank (C) and a (synchronic) lever (L) propelled wheelchair. All wheelchairs were analysed with respect to cardio-respiratory parameters ([Vdot]E, [Vdot]O2, HR, RER), power output and gross mechanical efficiency during a continuous exercise test (speed of the treadmill V = 0·96 ms; every third minute a one degree increase of the slope). Non-wheelchair users (NW: N = 10) were compared to wheelchair sportsmen (WS: N = 3).The cardio-respiratory strain of hand rim propulsion increases more swiftly for both R and S wheelchairs than for the C and L systems. Mechanical efficiency is significantly lower for the hand rim wheelchairs with a remarkably low efficiency for the S wheelchair. The S wheelchair however showed the lowest energy losses and a lower [Vdot]O2 compared to the R wheelchair, these being important modalities for high speed and long distance wheeling. The trend in the data was similar for the C and L wheelchairs. These systems showed a 2–3% higher mechanical efficiency in the NW group than for R and S wheelchairs. The trend in the data between wheelchairs for both groups is more or less identical, although the WS group showed lower cardiorespiratory responses and a higher mechanical efficiency. It is concluded that physiological testing of prototypes is useful and should be extended to biomechanical and anatomical aspects to learn more about the optimizing factors for efficiency and energy expenditure in the wheelchair/user interface.
A new and simple procedure has been developed that allows the direct transesterification of lipids, using aluminium chloride as a catalyst and methanol as the esterifying alcohol. The concentration of the salt and reaction conditions have been investigated for the different lipid classes. Comparative studies, performed with boron trifluoride-methanol, indicate that the same values are obtained when using either reagent. In addition, the method has been adapted for transesterification in the presence of silica gel and other adsorbents, thus allowing the preparation of fatty acid methyl or ethyl esters directly from samples previously fractionated by thin-layer chromatography. This new reagent is very stable and easy to handle, the fatty acids being generated in the same tube without further purification steps.
Fish oils containing n-3 fatty acids have been shown in humans to decrease platelet aggregation in vitro, lower plasma triglycerides, and to increase bleeding time. The in vivo effects of fish oils on microcirculatory blood flow in humans has not been studied to date. Twenty-one male subjects were randomly assigned to either olive oil (n = 10) or fish oil (n = 11) supplemented groups to determine the effects of these oils on capillary blood flow velocity (CBV) in the nailfold area. The subjects were given the oils for three weeks (1.5 g oil/10 kg b.wt./day) in a single blind study design. In addition to CBV plasma lipid profiles, blood viscosity, blood pressure and platelet and erythrocyte fatty acids were also determined prior to and after the dietary intervention. Fish oil supplementation significantly increased CBV, by 1.75-fold (0.144 +/- 0.069 to 0.253 +/- 0.147 mm/s). The olive oil group remained unchanged. Increased levels of n-3 fatty acids were noted in platelets and erythrocytes of the fish compared to olive oil-supplemented groups. Blood viscosity was unaltered in both groups, however, blood pressure in the olive oil supplemented group was significantly decreased. Plasma triglycerides were significantly decreased in the fish oil supplemented group. These observations suggest that increases in CBV after fish oil supplementation are due to changes in vascular tone and not to alterations in blood pressure or blood viscosity.
We have examined, in normal subjects, the effects of a daily dietary supplement of fish oil concentrate ('maxEPA'), providing 3 g of omega-3 fatty acids, on erythrocyte membrane phospholipids, erythrocyte deformability and blood viscosity. After 3 weeks, incorporation of C20:5 omega 3 into erythrocyte phosphatidyl choline (PC) was greater compared to phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS). After 6 weeks, there was no further increase in total erythrocyte C20:5 omega 3, but its distribution amongst phospholipid subclasses had changed. C20:5 omega 3 had increased further in PE and PS, but decreased in PC. Incorporation of C20:5 omega 3 also occurred into PC, PE and PS. omega-3 Fatty acids were incorporated almost entirely at the expense of C18:2 omega 6, but total unsaturation of phospholipids was increased. This is consistent with increased lipid fluidity, which may be an important determinant of erythrocyte deformability. The same dosage of maxEPA also resulted in a significant increase in erythrocyte deformability and a concomitant reduction in whole blood viscosity. Since plasma viscosity and haematocrit were unchanged it seems likely that the effects on blood rheology were mediated by changes in erythrocyte lipid fluidity. Modification of blood rheology by dietary omega-3 fatty acids is of potential value in the treatment of vascular disease.
1. Five healthy subjects took a daily supplement of 20 ml of linseed oil for 2 weeks. After a break of at least 6 weeks, the same subjects took a similar amount of MaxEPA (a fish oil fraction) for 2 weeks. The linseed oil supplement provided 9.38 g of linolenic acid (18:3 ω3) and the MaxEPA supplement provided 3.03 g of eicosapentaenoic acid (20:5 ω3) and 2.93 g of docosahexaenoic acid (22:6 ω3). The effects of the supplements on plasma lipid concentrations and on the fatty acid composition of platelet phosphoglycerides were studied.
2. In a second experiment, five male subjects took 5, 10 and 20 g of MaxEPA/day in random order for 3 week periods; each experimental period was separated by a break of at least 6 weeks. These doses of MaxEPA provided 0.83, 1.67 and 3.33 g of 20:5 ω3 and 0.80, 1.61 and 3.22 g 22:6 ω3 respectively. The effects of these supplements on plasma lipid concentrations, the fatty acid composition of platelet phosphoglycerides, template bleeding time and platelet aggregation induced by collagen and the prostaglandin analogue compound U46619 were studied.
3. In the platelet lipids, the proportion of 20:5 ω3 was increased by the 20 ml linseed oil supplement but the increase was small compared with the increase brought about by even 5 g of MaxEPA/day. The proportion of arachidonic acid (20:4 ω3) was substantially decreased by the MaxEPA supplement but not by the linseed oil supplement. The ratio of 20:4 ω6/20:5 ω3 fell from 32:1 in the control periods to 11:1 with 5 g, 7:1 with 10 g and 5:1 with 20 g of MaxEPA/day. The MaxEPA supplement also led to increases in the proportions of 22:5 ω3 and 22:6 ω3 and decreases in those of 20:3 ω6 and 22:4 ω6.
4. Bleeding times tended to be prolonged with the MaxEPA supplement but did not follow any dose-dependent trend. Platelet aggregation induced by both collagen and compound U46619 was not inhibited in vitro.
5. Plasma triglyceride concentrations were lowered by the MaxEPA supplement but not by the linseed oil supplement. Plasma triglyceride concentrations were substantially lowered by 10 g and 20 g of MaxEPA/day. Total plasma cholesterol concentrations were slightly lowered and HDL cholesterol concentrations were slightly increased by 20 g of MaxEPA/day. No other significant differences were noted.
Eicosapentaenoic acid (EPA), which is abundant in seafood, has been reported to be a potent antagonist of platelet aggregation and also to reduce the incidene of cardiovascular disorders. We recently reported that EPA also reduces whole blood viscosity. A highly purified EPA, in a soft capsule (75% ethylester form of EPA; EPA-E), manufactured from sardine oil was administered to 8 healthy male subjects for 4 weeks. No side effects were observed. Platelet aggregation and platelet retention significantly decreased. The EPA content in platelet phospholipids markedly increased but docosahexaenoic acid (DHA) and arachidonic acid (AA) contents did not change. A reduction in whole blood viscosity and an increase in erythrocyte deformability were also observed after 4 week's ingestion of EPA-E. The EPA content in erythrocyte membrane phospholipids markedly increased after 4 weeks, and was positively correlated with erythrocyte deformability. Reduction of platelet aggregation and improvement of the rheological properties of the erythrocyte might be explained by an increase in the EPA content in platelet and erythrocyte phospholipids.
The effects of L-carnitine on the pyruvate dehydrogenase (PDH) complex and carnitine palmitoyl transferase (CPT) were studied in muscle of 16 long-distance runners (LDR). These subjects received placebo or L-carnitine (2 g orally) during a 4-week period of training. Athletes receiving L-carnitine showed a dramatic increase (P < 0.001) in the PDH complex activities. By contrast, the levels of CPT, both 1 and 2, were unchanged. No significant changes were observed after placebo administration. We previously reported [Huertas R. et al., Biochem. Biophys. Res. Commun. 188 (1992) 102-107] that L-carnitine induces an increase in the activities of complexes I, III and IV of the respiratory chain in muscle of LDR. Taken together, our data suggest that the improvement in (maximal oxygen consumption) VO2max observed in LDR after L-carnitine administration is based on these biochemical findings.
In a randomized, placebo-controlled study the effect of 10 weeks of supplementation with either 5.2 g of a concentrated fish oil triglyceride (Triomar) enriched in omega-3 fatty acids (1.60 g/day EPA and 1.04 g/ day DHA) or 5.2 g corn oil (serving as placebo) on maximal aerobic power, anaerobic threshold and running performance was assessed in 28 well-trained male soccer players (18-35 years). Supplements were given as 650-mg capsules. Capsule assignment was randomized to one omega-3 group (n = 15), given eight Triomar capsules per day, and one placebo group (n = 13), given eight capsules of corn oil per day. During the 10-week supplementation period the subjects maintained their usual diets and training regimes. Red blood cell (RBC) osmotic fragility, triglycerides and fatty acid composition in plasma were assessed before and after the supplementation period. The pre- and post-supplementation tests of maximal aerobic power, anaerobic power and running performance showed no significant difference between the two groups. Subjects in the omega-3 group had significantly reduced plasma triglycerides, rose EPA (175%) and DHA (40%) in the total lipid fraction of plasma after supplementation. RBC osmotic fragility did not change. In conclusion, the results do not support the hypothesis that endurance athletes can improve maximal aerobic performance by omega 3-fatty acid supplementation.
The fatty acid composition of the diet has been found to influence the activity and sensitivity of mitochondrial carnitine palmitoyltransferase I (CPT I; EC 2.3.1.21) to inhibition by malonyl CoA in rat heart and skeletal muscle. The nutritional state of rats has been shown to have less influence on the activity and metabolic control of mitochondrial CPT I in heart and skeletal muscle tissue than in the liver, a tissue in which CPT I activity and sensitivity to inhibition by malonyl CoA can be shown to be regulated acutely under different nutritional conditions. However, because manipulation of the nutritional state in these previous studies was restricted mainly to examining the effect of starvation, this study was undertaken to determine whether, as in liver, the fatty acid content and composition of the diet can regulate the activity and metabolic control of CPT I in heart and skeletal muscle. Rats were fed for up to 10 wk either a nonpurified low fat diet (30 g fat/kg) or a high fat diet (200 g fat/kg) containing one of the following five oil types: hydrogenated coconut oil (HCO), olive oil (OO), safflower oil (SO), evening primrose oil (EPO) or menhaden (fish) oil (MO). Feeding a diet enriched in MO had the most pronounced effect. Rats fed MO had a significantly greater skeletal muscle CPT I specific activity and tissue capacity, and a lower sensitivity of CPT I to malonyl CoA inhibition compared with rats fed a low fat diet, but the duration of feeding required to modulate this sensitivity was longer than that observed previously for the liver enzyme. Progressively greater sensitivity of heart CPT I to malonyl CoA occurred with feeding duration in all groups. These studies indicate that the fatty acid composition of the diet is involved in the regulation of mitochondrial CPT I activity in heart and skeletal muscle.
The objective of the present study was to evaluate the effect of rehabilitation on physical capacity, mechanical efficiency of manual wheelchair propulsion, and performance of standardized activities of daily living (ADL).
Nineteen recently injured subjects with spinal cord injuries were tested on a wheelchair ergometer (maximal isometric strength, sprint and maximal power output, and peak oxygen uptake) and during standardized ADL (physical strain and performance time) at the beginning (t1) and at the end (t2) of the active rehabilitation period.
Paired Student t-tests showed significant increases for maximal isometric strength (24%, P < 0.01), sprint power output (l7%, P < 0.001) and maximal power output (38%, P < 0.001). Peak oxygen uptake showed no statistically significant improvement (11%, P = 0.06). Mechanical efficiency of submaximal wheelchair exercise was significantly higher at t2 (9.0%) compared to t1 (7.9%, P < 0.01). No significant differences were found for physical strain during ADL, except for passing a door (P < 0.05). Performance time showed a significant decrease for most tasks.
The results of this study show considerable improvements in physical capacity and mechanical efficiency of manual wheelchair propulsion during rehabilitation, and a concomitant lower performance time during standardized ADL. The higher mechanical efficiency and the decrease in performance time during standardized ADL suggest improvement in wheelchair propulsion technique.
Muscle or heart fatty acid-binding protein is a low molecular weight protein that binds long-chain fatty acids in the cytosol of muscle tissues. The three-dimensional structure of the human, bovine and insect proteins are known, either via X-ray or NMR techniques. The folding of the protein closely resembles that of the other FABPs: ten anti-parallel beta-strands are arranged to form a clam shell, closed at one end by two alpha-helices. This arrangement allows the formation of an internal cavity where the fatty acid can be accommodated, protected and isolated from the external environment. The fatty acid in the protein interior is stabilized by electrostatic and hydrogen bond interactions of its carboxylic head with charged or polar residues of the protein and by interactions of its tail with hydrophobic residues. The three-dimensional structure of different fatty acid-protein complexes along with molecular dynamics simulations are now providing insight into the molecular details of the specificity of the ligand binding.
The intracellular fatty acid-binding proteins (FABPs) comprise a family of 14-15 kDa proteins which bind long-chain fatty acids. A role for FABPs in fatty acid transport has been hypothesized for several decades, and the accumulated indirect and correlative evidence is largely supportive of this proposed function. In recent years, a number of experimental approaches which more directly examine the transport function of FABPs have been taken. These include molecular level in vitro modeling of fatty acid transfer mechanisms, whole cell studies of fatty acid uptake and intracellular transfer following genetic manipulation of FABP type and amount, and an examination of cells and tissues from animals engineered to lack expression of specific FABPs. Collectively, data from these studies have provided strong support for defining the FABPs as fatty acid transport proteins. Further studies are necessary to elucidate the fundamental mechanisms by which cellular fatty acid trafficking is modulated by the FABPs.
Endurance training and/or a fish oil supplemented diet affect cytoplasmic fatty acid binding protein (FABP(c)) content in rat skeletal muscles and heart. After 8 weeks of swimming, trained rats exhibited higher FABP(c) content in the extensor digitorum longus (EDL) and in the gastrocnemius than did control rats (30%). The FABP(c) increase was associated with an increase of citrate synthase activity (85% and 93%, respectively, in the two muscles), whereas lactate dehydrogenase activity decreased significantly. In contrast, in the soleus and in the heart we did not observe any effect of exercise either on FABP(c) or on the metabolic profile. Therefore, increasing oxidative capacities of muscle by exercise resulted in a concomitant increase of the FABP(c) content. Giving a polyunsaturated fatty acid (omega-3) supplemented diet for eight weeks induced a large rise of the FABP(c) in EDL (300%), gastrocnemius (250%), soleus (50%) and heart (15%) without a concurrent accumulation of intramuscular triglycerides or modification of the citrate synthase activity, suggesting that polyunsaturated fatty acids may increase FABP(c) content by up-regulating fatty acid metabolism genes via peroxisome proliferator-activated receptor alpha activation. Endurance trained rats fed with an omega-3 diet had similar FABP(c) content in the gastrocnemius muscle when compared to sedentary omega-3 fed rats, whereas an additive effect of exercise and diet was observed in the EDL. The FABP(c) in the soleus and in the heart of rats fed with omega-3 supplements remained constant whether rats performed exercise or not. As a result, both exercise and omega-3-enriched diet influenced FABP(c) content in muscle. These two physiological treatments presumably acted on FABP(c) content by increasing fatty acid flux within the cell.
It is still unknown whether the fatty acid composition of human skeletal muscle lipids is directly influenced by the fat composition of the diet.
We investigated whether the fatty acid composition of the diet is reflected in the fatty acid profile of skeletal muscle phospholipids and triacylglycerols.
Thirty-two healthy adults (25 men and 7 women) included in a larger controlled, multicenter dietary study were randomly assigned to diets containing a high proportion of either saturated fatty acids (SFAs) [total fat, 36% of energy; SFAs, 18% of energy; monounsaturated fatty acids (MUFAs), 10% of energy] or MUFAs (total fat, 35% of energy; SFAs, 9% of energy; MUFAs, 19% of energy) for 3 mo. Within each diet group, there was a second random assignment to supplementation with fish oil capsules [containing 3.6 g n-3 fatty acids/d; 2.4 g eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)] or placebo. A muscle biopsy sample was taken from the vastus lateralis muscle after the diet period. Parallel analyses of diet and supplementation effects were performed.
The proportions of myristic (14:0), pentadecanoic (15:0), heptadecanoic (17:0), and palmitoleic (16:1n-7) acids in the skeletal muscle phospholipids were higher and the proportion of oleic acid (18:1n-9) was lower in the SFA group than in the MUFA group. The proportion of total n-3 fatty acids in the muscle phospholipids was approximately 2.5 times higher, with a 5 times higher proportion of eicosapentaenoic acid (20:5n-3), in subjects supplemented with n-3 fatty acids than in those given placebo. Similar differences were observed in the skeletal muscle triacylglycerols.
The fatty acid composition of skeletal muscle lipids reflects the fatty acid composition of the diet in healthy men and women.
The purpose of this study was to examine changes in postprandial lipemia (PPL) in recreationally active males following aerobic exercise, omega-3 fatty acids (n-3FA) supplementation, and the combination of the two. PPL following a high-fat meal was measured in 10 recreationally active males (25 +/-1.5 years) under each of the following conditions: no exercise and no n-3 FA supplementation (control); exercise and no n-3FA supplementation (exercise); n-3FA supplementation and no exercise (n-3FA); and exercise and n-3 FA supplementation (combined). Blood was collected before the high-fat meal and at 2, 4, 6, and 8 hours after the meal to assess the PPL response. Supplementation consisted of 4.0 g of n-3FA per day for 5 weeks. Triglyceride (TG) peak response, the total area under the TG curve (TG-AUCT), and the incremental area under the TG curve (TG-AUCI) were used to define the PPL response. TG peak response was significantly reduced 38% by n-3FA supplementation and 50% by the combination of exercise and n-3FA supplementation. N-3FAs significantly reduced the TG-AUCT by 27% and by 42% when combined with exercise. When compared with the exercise trial, the TG-AUCT during the combined trial was significantly lower. Exercise, n-3FAs, and the combination significantly reduced the TG-AUCI by 40%, 42%, and 58%, respectively. These results suggest that the combination of exercise and n-3FA supplementation reduce PPL to a greater degree in recreationally active males when compared with the individual treatments.
Sports and exercise in midlife
- R M Glaser
- R.M. Glaser