Association between body folate status and muscle mass: a cross-sectional study of the National Health and Nutrition Examination Survey 2011-2018

BackgroundSarcopenia is a progressive muscle disease associated with loss of muscle mass, strength and function. Previous studies have shown that folate and muscle function are related, but the effect of body folate status on muscle mass is unknown. This study aimed to investigate the relationship between different forms of folate and muscle mass.MethodsThis cross-sectional study analyzed data from the 2011-2018 National Health and Nutrition Examination Survey (NHANES). Data on body folate (5-Methyl-tetrahydrofolate (5MTHF), serum total folate, and RBC folate), muscle mass (quantified by appendicular skeletal muscle mass index, ASMI), and covariates were extracted and analyzed. To examine the relationship between folate status and ASMI, weighted multivariable linear regression analyses and smooth curve fittings were performed, followed by subgroup analysis stratified by age, gender, and race. Threshold effect analysis was conducted when a nonlinearity relationship was detected.ResultsA total of 13,850 participants were included in the final analysis. RBC folate was positively associated with ASMI in all three models. Serum total folate and 5MTHF were negatively associated with ASMI in unadjusted and partially adjusted model, but not in fully adjusted model. When stratified by age, gender, and race, we observed positive associations between RBC folate and ASMI in 20-40 years old participants, men, Mexican/Hispanic, Non-Hispanic Black, and Other Race. Smooth curve fitting demonstrated a nonlinear relationship between RBC folate and ASMI, with the inflection point identified at 512 ng/mL. Stratified by age, gender, and race, nonlinear relationships remained in 20-40 years old participants, Men, Non-Hispanic Black and Other Race, with inflection points identified at 468 ng/mL, 547 ng/mL, 400 ng/mL, and 494 ng/mL, respectively.ConclusionThese findings suggested folate deficiency might play a role in muscle loss, and maintenance of RBC folate above 512 ng/mL might be helpful to the prevention and treatment of sarcopenia.