Association of Dietary Vitamin C Intake with the Risk of Metabolic Syndrome Among Adults: NHANES 2007-2018

Objectives: There has been discussion over the association between vitamin C intake and the risk of metabolic syndrome (MetS). This study examined the relationship between dietary vitamin C intake and the risk of MetS in a sizable adult American population. Methods: We examined the relationship between dietary vitamin C intake and the risk of MetS in 12,943 persons from the 2007 to 2018 National Health and Nutrition Examination Survey (NHANES). This association was then evaluated using logistic regression and restricted cubic spline models. Sex and age-based subgroup analyses were carried out. Results: According to the results of the multiple regression model, the risk of MetS was inversely correlated with dietary vitamin C intake, vitamin C intake derived from fruits and vegetables. The adjusted results (odds ratios with 95% confidence intervals) for the highest versus lowest tertile were 0.80 (0.68-0.93), 0.86 (0.75-0.98), and 0.80 (0.69-0.93). Subgroup analyses further showed that the negative correlation of dietary vitamin C intake with the risk of MetS was particularly pronounced among females, those in the 20-39 age group, and those in the ≥60 age group. The dose-response relationship's findings indicated that vitamin C from diet and fruits had a nonlinear correlation with the risk of MetS, whereas vitamin C from vegetables had a linear correlation. Conclusions: The risk of MetS in adult Americans was found to be negatively correlated with dietary vitamin C intake, particularly from fruits and vegetables.