Folic Acid Is Related to Muscle Strength and Vitamin A Is Related to Health-Related Quality of Life: Results of the Korea National Health and Nutrition Examination Survey (KNHANES VII 2016–2018)

This study investigated how folic acid affects muscle strength and the effects of vitamin A on quality of life in adults. Baseline data from the Korea National Health and Nutrition Examination Survey (KNHANES VII 2016–2018) was used to find 6112 adults (ages 19–80) meeting study criteria. The participants were divided into three groups: young adults (ages 19–39), middle-aged (ages 40–64), and elderly (≥65 years). Muscle strength was measured using a digital grip strength dynamometer. The EuroQol five-dimension questionnaire measured quality of life. Associations were assessed using multivariate regression and logistic regression. Vitamins and handgrip strength were divided into low and high groups based on the mean. Although vitamin A and folate levels were related to handgrip strength in all subjects, regression demonstrated a significant association between folate and handgrip strength in the elderly. The odds ratios (OR) of higher handgrip strength were statistically significant for elderly participants with high levels of folate compared to those with low levels (OR: 1.55). Vitamin A was associated with quality of life, especially in the self-care dimension for the elderly. Further longitudinal research is needed to examine the relationship between vitamins and muscle strength, as well as vitamins and quality of life.