A meta-analysis of the effects of long-chain n-3 polyunsaturated fatty acids on muscle mass and muscle strength in randomised controlled / 中华临床营养杂志

ABSTRACT

Objective:To investigate the effects of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation on muscle mass and strength improvement through systematic review and meta-analysis.Methods:Electronic databases, namely Cochrane Library database, MEDLINE, EMBASE, CENTRAL, China National Knowledge Infrastructure, and Wanfang were searched for publications in English and Chinese from database establishment to June 20, 2022. All randomized controlled trials involving any n-3 fatty acid (fish oil capsules, pure fish oil and oral nutritional supplements) interventions for more than 4 weeks among adults aged ≥ 18 years were included in the analysis. The effects of n-3 PUFA on muscle mass and strength were compared with controls using RevMan 5.4. The mean differences (MDs) or standardized mean differences (SMDs) with 95% confidence intervals (CI) were calculated and pooled effects were assessed. The quality of the included studies was evaluated using the Cochrane risk-of-bias tool.Results:27 trials were included, with both healthy adults and patients with various types of cancer, with chronic obstructive pulmonary disease and on hemodialysis due to chronic renal failure. Most trials were judged as "low" to "high" risk of bias. The meta-analysis showed that n-3 PUFA supplementation significantly improved the lean body mass in the group without physical activity intervention compared to the control group, while showing no significant increase in muscle mass or handgrip strength in overall participants. There was no significant difference between intervention and control groups in subgroup analyses based on health/disease condition, intervention duration, route of administration and dosage and risk of bias. However, significant increases in mid-arm muscle circumference (MAMC) and lower body strength (MD = 0.8, 95% CI 0.26 to 1.34, P = 0.005; SMD = 0.45, 95% CI 0.21 to 0.69, P = 0.0002) were observed in n-3 PUFA supplement group. Conclusions:This meta-analysis indicates that n-3 PUFA supplementation does not improve muscle mass or handgrip strength in healthy adults as well as patients, but do improve MAMC and lower body strength. The limited sample size and prominent heterogeneity of the included studies impede the extrapolation to clinical practice and warrants individual analysis based on population characteristics. Well-designed large-scale RCTs are required to verify these findings.