Several cohort studies have reported that the Japanese diet is associated with reduced cardiovascular disease mortality. However, the results were not always consistent, and most of those studies conducted dietary surveys around 1990. We investigated the association between the Japanese diet and coronary artery disease (CAD) in 802 patients undergoing coronary angiography. The Japanese diet score was defined as the sum of scores of the intakes of fish, soy products, vegetables, seaweed, fruits, and green tea. CAD was found in 511 patients, of whom 173 had myocardial infarction (MI). Intakes of fish, soy products, vegetables, seaweed, fruits, and green tea were lower in patients with CAD, especially in those with MI, than in those without CAD. As a result, the Japanese diet score was significantly lower in patients with CAD than in those without CAD (p < 0.001). To clarify the association between the Japanese diet and CAD, the 802 study patients were divided into three tertiles by the Japanese diet score. The proportion of CAD decreased with the Japanese diet score, reaching 72% in patients at T1 (lowest score), 63% at T2, and 55% at T3 (highest) (p < 0.05). The proportion of MI also decreased with the Japanese diet score, reaching 25% at T1, 24% at T2, and 15% at T3 (p < 0.05). In a multivariate analysis, compared with T1, the adjusted odds ratios for CAD and MI were 0.41 (95% confidence interval [CI]: 0.26-0.63) and 0.61 (95% CI: 0.38-0.99) for T3, respectively. Thus, the Japanese diet was found to be inversely associated with CAD in Japanese patients undergoing coronary angiography.
Keywords: Japanese diet; coronary angiography; coronary artery disease; food frequency questionnaire; myocardial infarction.