Ravindranath Duggirala, professor in the South Texas Diabetes and Obesity Institute at the University of Texas Rio Grande Valley, and Jairam K. P. Vanamala, associate professor of food science in Penn State's College of Agricultural Sciences, are the corresponding authors of the study, published in a recent issue of the American Journal of Clinical Nutrition.
Childhood obesity is a major public health issue that disproportionately affects Mexican-Americans. To assess childhood obesity and its related cardio-metabolic traits in Mexican-American children and adolescents from San Antonio, Texas, and surrounding areas — and to determine how those traits affect risk for future disease — Duggirala designed the San Antonio Family Assessment of Metabolic Risk Indicators in Youth (SAFARI) project. The family-based study enabled Duggirala and his colleagues to determine the relative roles of genes and environmental factors such as diet and physical activity in determining obesity-related traits in Mexican-American youth.
As part of SAFARI, obesity-related data were obtained from 670 nondiabetic children and youth, aged 6-17 years, from large, predominantly lower-income, Mexican-American families at increased risk of diabetes, adult members of which had previously participated in one of three community-based genetic epidemiologic studies in San Antonio. Vanamala's laboratory then measured provitamin A carotenoids — serum α- and β-carotenoid concentrations — in 570 of these children.
Serum carotenoids are associated with dietary fruit and vegetable intake. These carotenoids are the plant pigments that are responsible for the vibrant orange, yellow and green colors of cantaloupe, carrots, sweet potato, sweet red peppers, broccoli and green leafy vegetables.
Duggirala and Vanamala, working with first author Vidya S. Farook, of the South Texas Diabetes and Obesity Institute, found that α- and β-carotenoid concentrations were inversely correlated with obesity measures and triglyceride levels and positively correlated with HDL-C (good cholesterol) levels.
Since the SAFARI data were obtained from families, the researchers were able to characterize the genetic determinants of α- and β-carotene concentrations in the children and adolescents participating in the study. In addition, the investigators found that the inverse correlations between β-carotene and obesity-related traits and the positive correlation between β-carotene and HDL-C levels may themselves be influenced by genetic factors.
The researchers said the findings show the importance of fruit and vegetable intake for minimizing risk for obesity, while signifying potential disparities in fruit and vegetable intake in Mexican American children and a corresponding risk for obesity in these children.
The ultimate goal of the research is to find better ways to prevent or delay childhood obesity and associated cardio-metabolic risk. "The purpose of the SAFARI study is to identify genetic and environmental factors that influence childhood obesity risk," said SAFARI Principal Investigator Duggirala.
"It is important to identify genetic, environmental and lifestyle contributors to childhood obesity, which is associated with obesity and related conditions in adulthood," he said. "Our findings provide critical insights into the complex genetic architecture underlying the association between serum carotenoids and cardio-metabolic risk, and they highlight the need for culturally sensitive and family-based, early-life dietary interventions to combat the burden of obesity and its associated cardio-metabolic risk in Mexican American children and youth."
Vanamala noted that a plant-based diet — one that involves higher consumption of foods coming from plant sources such as fruits, vegetables and herbs as opposed to animal-based foods — decreases cardio-metabolic disease risk.
"However, the role of a plant-based diet, rich in α- and β-carotenes, in reducing the risk of developing obesity in children has not been well studied," he said. "Our current findings lend support to promoting fruit and vegetable consumption to reduce obesity as well as cardio-metabolic disease burden and to facilitating development of dietary interventions."
The research was funded primarily by the National Institute of Child Health and Human Development, a division of the National Institutes of Health, with additional support from Voelcker Foundation (Max and Minnie Tomerlin Voelcker Fund), and the USDA National Institute for Food and Agriculture.