Dietary protein intake is associated with lean mass change in older, community-dwelling adults: the Health, Aging, and Body Composition (Health ABC) Study.

BACKGROUND Dietary surveys suggest that many older, community-dwelling adults consume insufficient dietary protein, which may contribute to the age-related loss of lean mass (LM). OBJECTIVE The objective of the study was to determine the association between dietary protein and changes in total LM and nonbone appendicular LM (aLM) in older, community-dwelling men and women. DESIGN Dietary protein intake was assessed by using an interviewer-administered 108-item food-frequency questionnaire in men and women aged 70-79 y who were participating in the Health, Aging, and Body Composition study (n=2066). Changes in LM and aLM over 3 y were measured by using dual-energy X-ray absorptiometry. The association between protein intake and 3-y changes in LM and aLM was examined by using multiple linear regression analysis adjusted for potential confounders. RESULTS After adjustment for potential confounders, energy-adjusted protein intake was associated with 3-y changes in LM [beta (SE): 8.76 (3.00), P=0.004] and aLM [beta (SE): 5.31 (1.64), P=0.001]. Participants in the highest quintile of protein intake lost approximately 40% less LM and aLM than did those in the lowest quintile of protein intake (x+/-SE: -0.501+/-0.106 kg compared with -0.883+/-0.104 kg for LM; -0.400+/-0.058 kg compared with -0.661+/-0.057 kg for aLM; P for trend<0.01). The associations were attenuated slightly after adjustment for change in fat mass, but the results remained significant. CONCLUSION Dietary protein may be a modifiable risk factor for sarcopenia in older adults and should be studied further to determine its effects on preserving LM in this population.