Genetics of serum carotenoid concentrations and their correlation with obesity-related traits in Mexican American children

Abstract

Background: Dietary intake of phytonutrients present in fruits and vegetables, such as carotenoids, is associated with a lower risk of obesity and related traits, but the impact of genetic variation on these associations is poorly understood, especially in children.

Objective: We estimated common genetic influences on serum carotenoid concentrations and obesity-related traits in Mexican American (MA) children.

Design: Obesity-related data were obtained from 670 nondiabetic MA children, aged 6–17 y. Serum α- and β-carotenoid concentrations were measured in ∼570 (α-carotene in 565 and β-carotene in 572) of these children with the use of an ultraperformance liquid chromatography–photodiode array. We determined heritabilities for both carotenoids and examined their genetic relation with 10 obesity-related traits [body mass index (BMI), waist circumference (WC), high-density lipoprotein (HDL) cholesterol, triglycerides, fat mass (FM), systolic and diastolic blood pressure, fasting insulin and glucose, and homeostasis model assessment of insulin resistance] by using family data and a variance components approach. For these analyses, carotenoid values were inverse normalized, and all traits were adjusted for significant covariate effects of age and sex.

Results: Carotenoid concentrations were highly heritable and significant [α-carotene: heritability ( h ²) = 0.81, P = 6.7 × 10 ⁻¹¹; β-carotene: h ² = 0.90, P = 3.5 × 10 ⁻¹⁵]. After adjusting for multiple comparisons, we found significant ( P ≤ 0.05) negative phenotypic correlations between carotenoid concentrations and the following traits: BMI, WC, FM, and triglycerides (range: α-carotene = −0.19 to −0.12; β-carotene = −0.24 to −0.13) and positive correlations with HDL cholesterol (α-carotene = 0.17; β-carotene = 0.24). However, when the phenotypic correlations were partitioned into genetic and environmental correlations, we found marginally significant ( P = 0.051) genetic correlations only between β-carotene and BMI (−0.27), WC (−0.30), and HDL cholesterol (0.31) after accounting for multiple comparisons. None of the environmental correlations were significant.

Conclusions: The findings from this study suggest that the serum carotenoid concentrations were under strong additive genetic influences based on variance components analyses, and that the common genetic factors may influence β-carotene and obesity and lipid traits in MA children.