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.