Background. Glycemic index (GI) and glycemic load (GL) classify dietary carbohydrate by postprandial glycemia, an independent risk factor of atherosclerotic cardiovascular disease (ASCVD). Previous studies primarily assessed GI and GL with food frequency questionnaires, and findings on the relationships with ASCVD were inconsistent.
Objectives. To develop methodology for deriving dietary GI and GL from NHANES 24-hour recalls, and evaluate associations of GI/GL with prevalence of ASCVD and its risk factors in sex-specific analyses.
Methods. Among NHANES 2003–06 non-diabetic adult participants (age ≥20 years), cross-sectional associations of GI/GL with cardio-metabolic risk factors were evaluated in 1199 men and 955 women, and with prevalent ASCVD in 1690 men and 1563 women aged 40 and older. Multivariable modeling was used to adjust for potential confounding by age, race, education, familial heart disease, smoking, physical activity, body mass index, hormone replacement therapy (women) and other dietary factors. Odds ratios (OR) with 95% confidence intervals (CI) for the highest vs lowest quintiles, and p values for trend, are reported.
Results. Dietary GI was positively associated with impaired fasting glucose (IFG. OR=1.82 [95% CI: 1.20–2.75], p=0.005), high triglyceride (OR=3.20 [1.21–8.47], p=0.012), and low high-density lipoprotein (HDL. OR=1.81 [1.06–3.08], p=0.006) in men, and with abdominal obesity (OR=2.68 [1.55–4.66], p=0.009) in women. Dietary GL was positively associated with low HDL (OR=5.28 [2.87–9.71], p<0.0001), 1FG (OR=2.03 [1.02–4.03], p=0.039) and metabolic syndrome (OR=2.42 [1.24–4.71], p=0.041) in men, and with high LDL (OR=3.34 [1.04–10.77], p=0.036) and low HDL (OR=8.52 [1.98–36.76], p=0,004) in women. In stratified multivariate analyses, associations of GI/GL with cardio-metabolic risk factors and ASCVD were weaker in obese individuals.
Conclusion. The results of this research indicate a positive association between high GI and GL diets with prevalence of selected predictors of ASCVD, particularly in men. Stronger association in men may be partially attributed to higher prevalence of cardiometabolic risk factors (except for abdominal obesity) in men. Weaker associations in obese individuals may be attributed to reverse causation in cross-sectional design, which may have confounded the associations in the main results and needs to be clarified in large prospective studies.