Omega 3 (n-3) fatty acids have been shown to improve anabolic signalling pathways in muscle and prevent loss of muscle mass following severe burns in animal studies. Increased inflammation is thought to decrease the anabolic signal cascade in muscle by decreasing activation of the FRAP/mTOR signal pathway. A number of nutrients (such as the branched chain amino acids) are known to activate FRAP/mTOR and evidence from animal models suggests that n-3 fatty acids may affect anabolic pathways in muscle via this pathway. Because long chain n-3 fatty acids from fish are able to decrease inflammation via eicosanoid production, they may increase protein synthesis in muscle via an up regulation of the FRAP/mTOR signal pathway. Ageing is associated with a gradual decline in muscle mass termed sarcopaenia, which may be related to oxidative stress. This muscle loss is of interest because it is associated positively with total mortality.
Researchers1 have investigated the effects of n-3 fatty acids on muscle protein synthesis by randomly feeding 16 healthy adults (≥ 65y) either n-3 fatty acids (1.86g Eicosapentanoic acid and 1.5g docosahexanoic acid) or corn oil for 8 weeks. Rates of muscle protein synthesis were measured in the subject at baseline, as well after the 8 week supplementation study period. The results showed that neither corn oil not the n-3 fatty acids had any effect on muscle protein synthesis and did not change the degree of phosphorylation of anabolic signal cascades. However, n-3 fatty acids did increase muscle protein synthesis in response to infusion induced hyperaminoacidaemia-hyperinsulinaemia. This increased muscle protein synthesis in response to intravenous amino acid and insulin infusion was also accompanied by an increase in phosphorylation of the FRAP/mTOR pathway suggesting that anabolic pathways had been activated.
Other research (here) has reported that protein absorption and muscle protein synthesis does not differ between young and old men. These results therefore may suggest that if muscle protein synthesis rates are increase in response to n-3 fatty acids in elderly subjects, they may also be increased in young subjects. The inability of the muscle to correctly synthesis proteins at an optimal rate is termed anabolic resistance, and it appears from this data that n-3 fish oils may be able in some way to improve anabolic resistance. These results further suggest that the n-3 fatty acids are able to do this by in some way activating the FRAP/mTOR signal pathway and thus increase phosphorylation rates in muscle cells. The individuals in this study were all healthy, and it might therefore be expected that n-3 fatty acids would have an even greater affect on individuals with a systemic inflammatory condition.
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