Plasma glucose levels in the association between serum trans-β-carotene and obesity among children and adolescents

Abstract

Background Results on the association between trans-β-carotene and obesity are less clear and little is known about how their relationship may be affected by plasma glucose levels.The present study aimed to evaluate the relationships between trans-β-carotene and obesity and to investigate whether plasma glucose levels had a modifying effect on these relationships. Methods Children aged 6-18 years were selected from the National Health and Nutrition Examination Survey(NHANES) (2001–2006) (n =8030). The serum trans-β-carotene levels were divided into tertiles, and their associations with obesity were evaluated using multivariable-adjusted linear regression models adjusted for potential confounding factors. The interaction effects between trans-β-carotene levels and plasma glucose levels on obesity were further evaluated. Results In the fully adjusted model, using serum trans-β-carotene as natural log-transformed continuous variable, the negative association between trans-β-carotene level and obesity were confirmed. In addition, plasma glucose levels significantly modified the inverse association between trans-β-carotene and obesity (p value for interaction: 0.09). A stronger association of trans-β-carotene levels with obesity was found in higher plasma glucose levels (more than100 mg/dl) than in lower plasma glucose levels. Further, a non-linear relationship was detected between trans-β-carotene and obesity in participants with higher plasma glucose levels, with an inflection point of 2.7 (trans-β-carotene =14.88 ug/dl). The effect sizes and confidence intervals for the left and right sides of the inflection point were 0.10 (0.00 to 0.2) and 6.7 (0.1 to 348.2), respectively. Conclusion Our findings indicate that the association between trans-β-carotene concentration and obesity is stronger in individuals with higher plasma glucose population than in those with lower plasma glucose levels.