Résumé :
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[BDSP. Notice produite par INIST-CNRS IR0x79Dn. Diffusion soumise à autorisation]. The anticarcinogenic potential of vitamin D might be mediated by not only calcium metabolism but also other mechanisms initiated by vitamin D receptor (VDR). The authors measured plasma 25-hydroxyvitamin D in healthy volunteer examinees who underwent total colonoscopy in Tokyo, Japan, 2004-2005, and evaluated its influence on colorectal adenoma, both alone and in interaction with VDR polymorphisms, which correspond to the FokI and Taql restriction sites. The main analysis of plasma 25-hydroxyvitamin D included 737 cases and 703 controls. Compared with the lowest quintile of plasma 25-hydroxyvitamin D, only the highest was related to a significantly decreased odds ratio of colorectal adenoma (odds ratio =0.64,95 % confidence interval : 0.45,0.92). In contrast, all but the lowest quintile of dietary calcium intake presented similarly reduced odds ratios (odds ratio for the highest =0.67,95 % confidence interval : 0.47,0.95). Of note, the association between plasma 25-hydroxyvitamin D levels and colorectal adenoma was modified by the Taql polymorphism of the VDR gene (Pinteraction =0.03) but not by dietary calcium intake (Pinteraction =0.93). These observations highlight the importance of vitamin D in colorectal tumorigenesis. Vitamin D might protect against colorectal neoplasia, mainly through mechanisms other than the indirect mechanism via calcium metabolism.
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