Four grams per day of omega-3 fatty acids for eight weeks were found to increase the rate of muscle protein synthesis associated with increased supply of amino acids and insulin, according to findings published in the American Journal of Clinical Nutrition.
“Although the exact mechanisms by which omega-3 fatty acids stimulate muscle protein synthesis during hyperinsulinemia-hyperaminoacidemia remain to be resolved, our study provides compelling evidence of an interaction of omega-3 fatty acids and protein metabolism in human muscle and suggest that dietary omega-3 fatty acid supplementation could potentially provide a safe, simple, and low-cost intervention to combat sarcopenia,” wrote the researchers.
Bettina Mittendorfer, PhD, from the Division of Geriatrics and Nutritional Science at Washington University School of Medicine in Saint Louis and corresponding author of the study told NutraIngredients-USA.com that, as far as the researchers are aware, this is the first study to report potential anti-sarcopenia effects of omega-3 fatty acids.
Sarcopenia is a condition that affects the older generation, and is linked to a loss of lean body mass, strength and function.
In the US, some 45 percent of over-65 year-olds are thought to be impacted by the condition. A person in their 20s will have muscle that is up to 60 percent fat-free mass, whereas this drops to less than 40 percent for a 70 year-old.
“A major cause for the loss of muscle mass with advanced age is the inability of aging muscle to adequately increase the rate of muscle protein synthesis in response to nutritional stimuli (eg, amino acids and insulin),” explained the researchers.
In order to test if omega-3s may potentially benefit muscle health, the researchers recruited 16 healthy adults with an average age of 71 and an average BMI of 25.65 kg/m2, and randomly assigned them to receive either omega-3s or corn oil for eight weeks.
The study used four grams per day of Lovaza – the only omega-3 product allowed to make an FDA health claim (“lower very high triglycerides”) – and the intervention provided a daily doses of 1.86 grams of EPA (eicosapentaenoic acid) and 1.5 grams of DHA (docosahexaenoic acid).
“We chose this dose because it is the dose approved by the Food and Drug Administration for lowering plasma triglyceride concentrations in hypertriglyceridemic subjects and has therefore previously been shown to be physiologically relevant in human subjects,” explained the researchers.
Results showed that, although there were no differences between the groups in terms of “the basal rate of muscle protein synthesis”, wrote the researchers in the AJCN, an augmentation in the “hyperaminoacidemia-hyperinsulinemia–induced increase in the rate of muscle protein synthesis” was reported.
This observation was accompanied by a greater increase in the activation of a signalling pathway called mTOR-p70s6k, which is reported to be an “integral control point for muscle cell growth”. The actual mechanism remains to be elucidated, said the researchers.
“In the present study, we provide novel evidence that dietary omega-3 fatty acid supplementation augments the hyperaminoacidemia- hyperinsulinemia induced increase in the rate of muscle protein synthesis in older adults,” wrote Dr Mittendorfer and her co-workers.
“Omega-3 fatty acids therefore probably attenuate the anabolic resistance and may potentially be useful as a therapeutic agent to treat sarcopenia,” they added.
Dr Mittendorfer confirmed that the researchers are to repeat the study with "more subjects plus functional outcomes".
The study’s researchers were affiliated with Washington University School of Medicine in Saint Louis and the University of Nottingham in England. The study was funded by the National Institutes of Health,
Source: The American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.110.005611
“Dietary omega-3 fatty acid supplementation increases the rate of muscle protein synthesis in older adults: a randomized controlled trial”
Authors: G.I. Smith, P. Atherton, D.N. Reeds, B.S. Mohammed, D. Rankin, M.J. Rennie, B. Mittendorfer