Role of Phytochemicals in Lifestyle-related Disease Prevention

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We investigated the effect of several phytochemicals on lifestyle-related disease prevention using a cell culture system and animal models that we developed. Among these phytochemicals, we clarified that soy isoflavones were effective for lifestyle-related disease prevention, and were good for human health.Investigating the effects of soy protein and isoflavones on blood pressure and cholesterol levels among high risk middle-aged Scottish men, we could observed significant reductions from the baselines in systolic blood pressure(SBP) and diastolic blood pressure, total cholesterol and non-high density lipoprotein cholesterol in the group consuming a diet containing soy nutrients. To further investigate dietary factors preventing cardiovascular diseases, we divided world-wide populations examined by the WHO-CARDIAC study covering 60 study sites in 25 countries into the eaters and non-eaters of soybeans and evaluated risk factors for cardiovascular diseases. Among 1801 examinees whose 24h isoflavones were assayed, soy eaters had significantly lower body mass index, SBP and total-cholesterol than non-eaters.To clarify the mechanism of this effect of isoflavones, we tested the hypothesis that genistein, one of the phytochemicals, may exert significant endothelial protection. Genistein acts as an antioxidant at the transcription level by the downregulation of p22phox and AT1 receptor expression. Our data also showed that the PPAR γ pathway was involved, at least in part, in the inhibitory effect of genistein on the expression of p22phox and AT1 receptors. We further studied the effects of isoflavone aglycones(IFA) on the production of nitric oxide(NO) and SBP in stroke-prone spontaneously hypertensive rats(SHRSP). After the administration of IFA, significant decreases in SBP were confirmed in the IFA group compared to the control group. Significantly higher levels of eNOS mRNA were also confirmed in the IFA group than in the control group.