The relationship between serum folate and grip strength in American adults

Summary We used data from NHANES to explore the associations between serum folate and grip strength, and found that high levels of serum folate were associated with increased grip strength among females rather than males. It is recommended to maintain a proper level of serum folate, especially in women. Purpose Associations and dose–response relationships between serum total folate, 5-methyltetrahydrofolate, and grip strength in general adults were unknown. Thus, we conducted this analysis for further exploration. Methods Data from the National Health and Nutrition Examination Survey (NHANES) database of 2011–2014 cycle were used. The independent variables including serum total folate, combined total folate (total folate plus Mefox), and 5-methyltetrahydrofolate. The dependent variable was BMI-corrected grip strength. Linear regression and the restricted cubic splines were used in our analyses. Results A total of 9079 adults aged over 20 years were included. In multivariate-adjusted model 2, compared with quartile (Q) 1, grip strength increased in Q3 of combined total folate and total folate, and the weighted β values with 95% confidence intervals ( CIs ) of grip strength were 0.06 (0.01, 0.12) and 0.06 (0.00, 0.10) for combined total folate and total folate, respectively. In the stratified analysis by gender, positive relationships between combined total folate, total folate, and 5-methyltetrahydrofolate and grip strength were found only in females, with β (95% CIs ) of 0.07 (0.02, 0.12), 0.07 (0.03, 0.12), and 0.09 (0.05, 0.13) for combined total folate, total folate, and 5-methyltetrahydrofolate in Q4, respectively. Non-linear positive dose–response relationships between serum folate and grip strength were also found only in females, not in males. Conclusion Our study suggested a positive association between serum folate and grip strength, while this positive association was only found in females; besides, the dose–response relationships were in a non-linear trend. Thus, it is recommended to maintain a proper serum folate level to keep better muscle strength, especially for women.