Carbohydrate-based diet may increase the risk of cardiovascular disease: A pooled analysis of two prospective cohort studies.

BACKGROUND & AIMS: According to cumulative epidemiologic studies, balancing macronutrients for energy is important to prevent metabolic diseases; however, this has not been studied extensively in Asian populations whose carbohydrate intake levels are relatively high. Therefore, we aimed to investigate the longitudinal association between carbohydrate intake and cardiovascular disease (CVD) among Korean adults in two community-based cohort studies.

METHODS: We included 9608 and 164,088 participants from the Korean Association Resource and Health Examinee studies, respectively, in the analysis. Carbohydrate intake was estimated using a validated semi-quantitative food frequency questionnaire. The proportion of total energy from carbohydrate (P_CARB) was calculated, and participants were divided into sex-specific quartiles based on their P_CARB values. Incident cases of CVD, including myocardial infarction, coronary artery disease, and stroke, were identified through self-reported questionnaires. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between P_CARB and CVD risk. The fixed effects model was used to pool the results.

RESULTS: In the fully adjusted model, significant positive associations between P_CARB and CVD risk were observed in the pooled analysis, showing that the HRs (95% CIs) for CVD across increasing quartiles of P_CARB were 1.00 (reference), 1.16 (0.94-1.44), 1.25 (0.96-1.63), and 1.48 (1.08-2.03). The restricted cubic spline regression analysis confirmed a linear dose-response relationship between P_CARB and CVD risk in both cohort studies, with all p-values for nonlinearity >0.05.

CONCLUSION: Our findings suggest that a carbohydrate-based diet high in proportion to total energy intake may increase the risk of CVD among middle-aged Korean adults, underscoring the importance of balanced macronutrient distribution. However, more research is needed to evaluate the sources and quality of carbohydrates in relation to CVD risk in this population.