Dietary Protein and Preservation of Physical Functioning Among Middle-aged and Older Adults in the Framingham Offspring Study

Abstract

Dietary protein may help prevent age-related declines in strength and functional capacity. This study examines the independent relation between dietary protein and longitudinal changes in physical functioning among Framingham Offspring Study adults from Exams 5 (1991-1995) to 8 (2005-2008). Protein intakes were derived from three-day diet records during exams 3 and 5; functional status was determined over 12 years using seven items selected from standardized questionnaires. Multivariable models were used to adjust for age, sex, education, physical activity, smoking, height, and energy intake. Functional tasks that benefitted most from a higher-protein diet (≥1.2 vs.<0.8 g/kg/day) were doing heavy work at home, walking ½ mile, going up and down stairs, stooping/kneeling/crouching, and lifting heavy items. Those with higher protein intakes were 41% less likely (95% CI: 0.43, 0.82) to become dependent in one or more of the functional tasks over follow-up. Higher physical activity and lower body mass index were both independently associated with less functional decline. The greatest risk reductions were found among those with higher protein intakes combined with either higher physical activity, more skeletal muscle mass, or lower BMI. This study demonstrates that dietary protein intakes above the current RDA may slow functional decline in older adults.