Association between Vitamin C Supplements and Frailty in Korean Older Adults: Analysis of the 2018–2019 Korea National Health and Nutrition Examination Surveys

Abstract

Abstract Background Frailty increases with age and as a result, older adults suffer from increased medical problems and reduced daily living abilities. However, few studies have examined the association between vitamin C intake and frailty among older adults. Therefore, we investigated the association between vitamin C supplementation and frailty in Koreans aged ≥ 65 years. Methods In the Korean National Health and Nutrition Examination Survey (2018–2019), participants were divided into a group that did not consume dietary supplements (non-DS, n = 1,530) and a group that consumed vitamin C supplements (vitamin C, n = 179). The group that consumed vitamin C was further divided into subgroups; those that consumed less than the recommended daily amount of vitamin C (< 100 mg) and those that consumed the recommended daily amount (100–999 mg, 1000–1999 mg, ≥ 2000 mg). Participants were also divided based on the duration of supplement intake (< 1 year, ≥ 1 year). The odds ratios (OR) and 95% confidence intervals (CI) of frailty and vitamin C intake were analyzed using multivariate logistic regression analysis adjusted for age, sex, education level, income level, living status (alone or not alone), body mass index, drinking frequency, smoking status, presence of chronic disease, and protein and fat intake. Results Older participants who consumed vitamin C supplements were at a reduced risk of frailty (OR: 0.39, 95% CI: 0.18–0.83) than those who did not consume vitamin C supplements. Participants who met adequate vitamin C daily requirements (≥ 100) exhibited a significantly improved risk of frailty (OR: 0.55, 95% CI: 0.32–0.95) than those who did not consume a sufficient amount of vitamin C. As vitamin C intake increased, the risk of developing frailty adversely decreased (OR: 0.37, 95% CI: 0.16–0.84, p = 0.008). Continuous intake of vitamin C for more than a year (OR: 0.25, 95% CI: 0.10–0.63) also lowered the risk of frailty. Conclusions These results suggest that adequate vitamin C intake to meet daily requirements is more likely to be effective in the management of frailty and that additional vitamin C intake for a sufficient period based on a regular diet is also expected to help manage frailty.