The apparent inverse association between dietary carotene intake and risk of cardiovascular mortality disappeared after adjustment for other cardioprotective dietary intakes: The Japan collaborative cohort study

Abstract

Background and purposeAn effect of dietary carotenes on risk of cardiovascular disease (CVD) is uncertain. We aimed to investigate whether the association between dietary carotenes intake and risk of CVD mortality will persist after controlling for the intakes of potential cardioprotective dietary factors that correlate with dietary alpha- and/or beta-carotenes. Methods and resultsWe followed up a total of 58,646 Japanese between 1988 and 1990 and 2009. We used a food frequency questionnaire (FFQ) to determine the dietary intakes of carotenes, and estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) of CVD mortality in relation to carotene intake by the proportional hazard regression developed by David Cox. During 965,970 person-years of follow-up (median 19.3 years), we identified 3388 total CVD deaths. After adjusting for demographic and lifestyle factors, dietary intakes of alpha-carotene were significantly associated with the reduced risk of mortality from coronary heart disease (CHD); adjusted HR (95% CI) in the highest versus lowest quintiles of intake was 0.75 (0.58–0.96; P-trend = 0.02) and dietary intakes of beta-carotene were significantly associated with the reduced risk of mortality from CVD, CHD, and other CVD; adjusted HRs (95% CIs) were 0.88 (0.79–0.98; P-trend = 0.04), 0.78 (0.61–0.99; P-trend = 0.01), and 0.81 (0.67–0.98; P-trend = 0.04), respectively. However, after further adjusting for the dietary intakes of potassium, calcium, vitamins C, E, or K, these associations disappeared. Conclusions—Dietary alpha- and beta-carotene intakes were not associated with risk of CVD mortality after controlling for intakes of other potential cardioprotective nutrients.