Association between dietary protein intake and grip strength among adults aged 51 years and over: What We Eat in America, National Health and Nutrition Examination Survey 2011-2014

INTRODUCTION Distributing daily protein intake evenly across meals (∼25-30g/meal) has been suggested to improve muscle mass. The aim of this research is to examine the association between grip strength, total protein intake and its distribution across day's meals in older adults. METHODS Nationally representative dietary intake data of adults aged 51 years and older (n = 4,123) who participated in What We Eat in America, NHANES 2011-2014 were analyzed. Protein intake per day and per eating occasion (breakfast, lunch, dinner, and snack) were determined. Combined grip strength was calculated and expressed in kilograms. Grip strength of individuals consuming ≥25g protein at 1 eating occasion was compared with those consuming same level of protein at 2 and 3 or more eating occasions. Grip strength of individuals in quartile 1 of daily protein intake was compared to those in the other quartiles. All associations were examined without and with adjustment for age, race/ethnicity, physical activity, health status, and smoking status. The comparison involving eating occasions and protein intake quartiles were further adjusted for daily protein intake and energy intake, respectively. RESULTS Only 33% of men and 19% of women had protein intake of ≥25g at 2 or more eating occasions. These individuals also had higher grip strength and daily protein intake. Grip strength was positively associated with consumption of ≥25g protein at 2 eating occasions as compared to consumption of same level of protein at 1 eating occasion (p<0.05) in unadjusted model, but not when adjusted. Grip strength was positively associated with daily protein intake among women in quartiles 3 and 4 (p<0.05) of protein intake in both unadjusted and adjusted models compared to lowest protein intake. Among men, grip strength was associated with daily protein intake in quartiles 3 and 4 (p<0.05) in the unadjusted model, but not when adjusted. CONCLUSION In a nationally representative sample of older adults, consuming ≥25g protein at 2 or more eating occasions was not associated with grip strength. However, higher daily protein intake was positively associated with grip strength in women.