Plasma omega-3 fatty acids are positively associated with appendicular muscle mass index only in adults with low protein intake: Results from NHANES 2011–2012

Omega-3 (ω-3) fatty acids may indirectly increase muscle protein synthesis making the muscle more sensitive to amino acids uptake; therefore, ω-3 could promote benefits on muscle mass mainly when protein intake is low. However, no study has evaluated the association between ω-3 fatty acids and muscle mass according to protein intake. To evaluate the association between plasma ω-3 fatty acids and appendicular muscle mass index (AMMI) in adults according to the protein intake. A cross-sectional study was performed evaluating 1037 individuals aged 20–59 years from a sub-sample of the National Health and Nutrition Examination Survey (NHANES) 2011–2012. Gas chromatography-mass spectrometry method was used to assess plasma ω-3 fatty acids. The lean mass was evaluated by dual-energy x-ray absorptiometry (DXA) and AMMI (kg/m2) was calculated by appendicular lean mass (kg) divided by height squared. The evaluation of protein intake was performed using two 24-h dietary recalls. Linear regression analysis was performed to assess the association of total plasma ω-3, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), alpha-linolenic acid (ALA), and EPA plus DHA with AMMI according to protein intake (