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

Background: Omega-3 (6)-3) fatty acids may indirectly increase muscle protein synthesis making the muscle more sensitive to amino acids uptake; therefore, 6)-3 could promote benefits on muscle mass mainly when protein intake is low. However, no study has evaluated the association between 6)-3 fatty acids and muscle mass according to protein intake. Aim: To evaluate the association between plasma 6)-3 fatty acids and appendicular muscle mass index (AMMI) in adults according to the protein intake. Methods: 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 6)-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 6)-3, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), alpha-linolenic acid (ALA), and EPA plus DHA with AMMI according to protein intake (<0.8; >= 0.8; >= 0.8 -<1.2; >= 1.2 -<1.6; and >= 1.6 g/kg/d). Results: Total plasma 6)-3 (0 = 0.0030; CI = 0.0013-0.0046; p = 0.002), ALA (0 = 0.0063; CI = 0.0020 -0.0107; p = 0.008), EPA (0 = 0.0073; CI = 0.0005-0.0142, p = 0.037), DHA (0 = 0.0057; CI = 0.0022 -0.0093; p = 0.004) and EPA + DHA (0 = 0.0040; CI = 0.0010-0.0071; p = 0.013) were positively associated with AMMI in individuals with low protein intake (<0.8 g/kg). However, no association was observed in individuals with protein intake higher than 0.8 g/kg. Conclusion: Plasma 6)-3 fatty acids were positively associated with AMMI only in individuals with low protein intake. (c) 2022 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Automated summary

This study evaluated the association between plasma omega-3 (6)-3 fatty acids and appendicular muscle mass index (AMMI) in adults, taking into account protein intake. The results showed a positive correlation between plasma omega-3 (6)-3 fatty acids and AMMI in individuals with low protein intake, indicating potential benefits of omega-3 (6)-3 fatty acid supplementation for muscle mass when protein intake is inadequate.