Relationship between protein intake and grip strength in qualitative and quantitative aspects among the elderly in Korea: results from the Korea National Health and Nutrition Examination Survey

BACKGROUND: This study investigated the association between quantitative and qualitative protein intake and grip strength (GS) in the South Korean population to explore nutritional management for the prevention of sarcopenia. METHODS: This cross-sectional study was based on data from a nationally representative sample of the South Korean elderly population, consisting of 1,531 men and 1,983 women aged 65 years and older who participated in the Korean National Health and Nutrition Examination Survey from 2016 to 2019. Low GS was defined as GS < 28 kg in men and GS < 18 kg in women. Protein intake was assessed using 1-day 24-h recall, and we analyzed absolute protein intake, protein intake by food source, and protein intake compared to dietary reference intake with per body weight or absolute daily recommended value. RESULTS: The total and animal protein intake and protein intake from legumes, fish and shellfish were significantly lower in women with a low GS than in those with a normal GS. After adjusting for confounding factors, women who consumed more protein than the estimated average requirement (EAR, 40 g/day for women) were 0.528 times less likely to have low GS than women consuming less protein than the EAR (95% CI: 0.373–0.749), and consuming any amount of protein from legumes were 0.656 times less likely (95% CI: 0.500–0.860) to have low GS than women who did not consume any amount of legume protein. CONCLUSIONS: This study provides epidemiological evidence that adequate protein intake above EAR and protein intake from legumes should be guided for preventing low GS, especially in elderly women.