Protein intake per day and at each daily meal and skeletal muscle mass declines among older community dwellers in Japan

Objective: To examine associations between protein intake per day and at different meals and skeletal muscle mass declines. Design: Two-year prospective cohort study among older community dwellers. Setting: National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) in Japan. Participants: Older men (n 292) and women (n 363) aged 60-87 years who participated in the baseline (2006-2008) and follow-up studies (2008-2010) of NILS-LSA and did not exhibit low skeletal muscle mass at baseline. Muscle mass was assessed using dual-energy X-ray absorptiometry at baseline and follow-up. Low muscle mass was defined as skeletal muscle mass index Results: Mean (sd) protein intake at breakfast, lunch and dinner was 22 center dot 7 (7 center dot 8), 26 center dot 7 (9 center dot 3) and 37 center dot 4 (10 center dot 5) g for men and 19 center dot 3 (6 center dot 3), 23 center dot 2 (7 center dot 3) and 28 center dot 5 (7 center dot 0) g for women, respectively. After adjusting for age, baseline skeletal muscle mass and other confounders in logistic modelling, greater total protein intake was associated with lower prevalence of skeletal muscle mass decline among men at follow-up (P = 0 center dot 024). Particularly, the OR (95 % CI) for high lunchtime protein intake was low (0 center dot 11 (0 center dot 02, 0 center dot 61); P = 0 center dot 01). No significant association between total protein intake and prevalence of skeletal muscle mass decline was found among women. Conclusions: High total protein intake, particularly at lunchtime, is associated with retention of skeletal muscle mass in men.