Association between vitamin levels and obesity in the national health and nutrition examination surveys 2017 to 2018

In recent years, the rapidly increasing incidence of obesity is becoming a worldwide public health problem. Obesity is a chronic disease which may have a major negative effect on the people's quality of life. Previous studies on the comprehensive effects of multivitamins on central obesity and general obesity are relatively few. The aim of this study was to evaluate association of vitamins exposure with obesity risk and obesity-related indicators. We fitted three statistical models (linear regression model, logistic regression model, and Bayesian kernel machine regression model) to evaluate the correlation between vitamin levels and obesity in the study population. The vitamin score represents the overall level of vitamin in serum, which was mutually verified with the results obtained from statistical model. The vitamin (A, C, and D) levels were significantly higher among non-obesity group compared to the obesity group. Using the lowest quartile of vitamin level as a referent, vitamin A, C, and D levels showed significantly negative correlation with the obesity risk in both adjusted and unadjusted models. When considering all vitamin as a mixed exposure, we found a generally negative relationship between vitamin mixtures with binary outcome (obesity) and continuous outcome (BMI, waist circumference, and hsCRP). Reduced levels of vitamins (A, C and D) increased the risk of obesity. Increased levels of vitamin mixtures can significantly reduce obesity risk and obesity-related indicators. Vitamins may reduce the risk of obesity by suppressing inflammatory responses.