Dietary protein intake, animal-to-plant protein ratio, and risk of sarcopenia in community-dwelling adults: a 9-year follow-up study

OBJECTIVE: This study aimed to examine the association between protein intake and risk of sarcopenia, with a specific focus on protein sources, in middle-aged and older adults. DESIGN: This was a 9-year follow-up study. Dietary protein intake was assessed by a validated food frequency questionnaire with energy adjustment using the residual method. Sarcopenia was defined by using height-adjusted appendicular lean mass and grip strength. Adjusted odds ratios (ORs) for sarcopenia were calculated by multivariable logistic regression analysis. SETTING: Baseline surveys (2011-2014) for the Murakami and Uonuma cohorts assessed body size, lifestyle, and medical history. Sarcopenia-related measurements were conducted in 2021-2022 in Murakami, Sekikawa, Uonuma, and Minamiuonuma, Japan. PARTICIPANTS: 6,232 individuals aged 40-74 years (mean age, 62.4 years; females, 54.8%). RESULTS: for trend=0.018), although total and animal protein intakes were not. Animal-to-plant protein ratio was U-shaped in its association with sarcopenia; adjusted ORs for the lowest and highest quintiles of the ratio compared to the middle quintile were 1.71 (95%CI: 0.96-3.07) and 1.97 (95%CI: 1.10-3.53), respectively, for males (P for quadratic term=0.017), and 1.93 (95%CI: 1.06-3.51) and 1.65 (95%CI: 0.90-3.05), respectively, for females (P for quadratic term=0.010). CONCLUSIONS: An imbalanced intake of plant and animal proteins may increase the risk of sarcopenia, highlighting the importance of balanced protein intake.