Introduction: There is growing evidence to support that dietary glycemic index (GI), a measure of carbohydrate quality, and glycemic load (GL), a measure of carbohydrate quantity and quality, is associated with cardiovascular (CV) disease in adults. Studies in children are scarce and tend to be cross-sectional and have low power. The aim of this study was to evaluate whether GI and GL predict CV risk factors in children over a 2-year period.
Methods: This study used data from the QUALITY study which recruited children aged 8-10 years with parental history of obesity, to assess the natural history and consequences of the development of obesity in youth. Three 24-hour recalls were administered at baseline and average daily GI and GL scores were calculated using the International Table of GI for each participant. CV risk factors measured at 2 years of follow-up included BMI z-score, percent fat mass, triglycerides, LDL and HDL cholesterol, and systolic (SBP) and diastolic (DBP) blood pressure. We used multiple imputation for missing data and Goldberg's equation to identify underreporters. Main analyses consisted of multiple linear regression with restricted cubic splines adjusted for confounders (age, sex, tanner stage, physical activity, family income, diet, screen time). Mediation by adiposity was evaluated using the Baron and Kenny approach.
Results: Mean age at baseline was 9.6 years. Thirty-three percent of children were overweight or obese. After two years, GI did not predict any CV risk factors in multivariable-adjusted regressions but GL positively predicted BMI z-score (ß = 0.05, 95% CI = 0.01 to 0.09), triglycerides (ß = 0.02, 95% CI = 0.004 to 0.03) and LDL cholesterol (ß = 0.04, 95% CI = 0.01 to 0.06) but not percent fat mass, HDL cholesterol and blood pressure. Mediation analysis revealed that the relationships between GL and TG (Sobel=2.9, p=0.004) and LDL (Sobel=3.0, p=0.003) were partially mediated by BMI (34% and 31% respectively).
Conclusion: Our results suggest that GL, but not GI, is predictive of LDL cholesterol and triglycerides in school-aged children, a relationship that is partially mediated by the effect of GL on adiposity. Focusing on lowering dietary sugar by favoring low GL diets may improve cardiometabolic health in children who enter puberty.