Effects of fish oil-derived n-3 polyunsaturated fatty acid on body composition, muscle strength and physical performance in older people: a secondary analysis of a randomised, double-blind, placebo-controlled trial

Background the effects regarding n-3 polyunsaturated fatty acid (n-3 PUFA) supplementation on sarcopenia have been explored by several clinical trials. Nonetheless, the use of n-3 PUFA for improving body composition, muscle strength and physical performance in older people is conflicting. Objectives our aim was to perform a randomised, double-blind, controlled trial to evaluate the effects of 6-month n-3 PUFA supplementation on body composition, muscle strength and physical performance in older Chinese people. Methods in this double-blind, placebo-controlled trial, 200 eligible subjects were randomly assigned to receive 4 g/day fish oil capsules (1.34 g eicosapentaenoic [EPA] + 1.07 docosahexaenoic [DHA]) or 4 g/day corn oil capsules (EPA + DHA <0.05 g) for 6 months. The primary outcomes were the changes of body composition, muscle strength (hand grip strength) and physical performance (Timed Up and Go time). Secondary outcomes were the changes in serum lipid profiles. Results compared with control group, fish oil-derived n-3 PUFA supplementation resulted in significant increases in thigh circumference (interaction (time x group) effect P < 0.001), total skeletal muscle mass (interaction (time x group) effect P < 0.001) and appendicular skeletal muscle mass (interaction (time x group) effect P < 0.001); the differences were still significant even after height correction. Muscle strength and physical performance including hand grip strength (interaction (time x group) effect P < 0.001) and Timed Up and Go time (interaction (time x group) effect P < 0.001) were also improved after a 6-month fish oil-derived n-3 PUFA intervention. In terms of serum lipid profiles, fish oil-derived n-3 PUFA supplementation could significantly reduce serum level of triglyceride (interaction (time x group) effect P = 0.012) and increase high density lipoprotein cholesterol (interaction (time x group) effect P < 0.001); while no significant improvement was found in serum concentrations of total cholesterol (interaction (time x group) effect P = 0.413) and low density lipoprotein cholesterol (interaction (time x group) effect P = 0.089). Conclusions our present trial demonstrated that a 6-month fish oil-derived n-3 PUFA supplementation could beneficially affect the body composition, muscle strength, physical performance and serum lipid profiles in older people, which could be into considerations when making strategies aiming to the primary prevention of sarcopenia.