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Dietary Folate consumption and Breast Cancer risk
It is known that defiency in dietary folate may predispose individuals to cancer, as a deficiency disrupts DNA synthesis and repair.Heavy intake of alcohol is also associated with elevated risks of breast cancer, but few studies have examined the relationship between folates and alcohol.

An important paper by TE Rohan , Meera et al published in the Journal of the National Cancer Institute has found that the combination of high folate intake and moderate consumption of alcohol shows a marked reduction in incidence of breast cancer.

The researchers examined the association between dietary folate intake and breast cancer risk and its modifications by methionine and alcohol intake in a cohort study of 56,837 women in the Canadian National Breast Screening study. The participants completed a self administered food frequency questionnaire covering 86 food items, including alcohol. The values for folate intake were from dietary sources alone, since data on the content of vitamin supplements was not available. Major sources were liver, green leafy vegetables and whole grain cereals. 1469 women were diagnosed with invasive carcinoma of the breast during the follow up between 1980 and 1993. A control group of 5382 women was also set up at random from the 56,837 participants.

Overall, as well as in post menopausal women alone, there was no association between dietary folate intake alone and breast cancer risk. Risk varied little in association with folate intake among women in the lowest 80% of the distribution of alcohol consumption ( i.e. less than one 14g unit a day) but there were marked reductions in risk associated with folate intake among those consuming more than 14g of alcohol a day, rising again at higher levels of alcohol intake.The pattern was more pronounced in post menopausal women. The study findings were similar after adjustment for years of education, use of oral contraceptives, weight and cigarettes. Participants using vitamin supplements were also excluded as well as subjects with a history of non malignant breast disease or other cancers. The authors conclude: ' Our results, although possibly chance findings, suggest that dietary folate consumption might be associated with reduced risk of breast cancer at relatively high levels of alcohol consumption, particularly in post menopausal women. Zhang et al observed a similar phenomenon in association with total folate intake (dietary plus supplement) in both post and pre menopausal women. Other epidemiological studies of folate and breast cancer have not examined risk by levels of alcohol.....our findings suggest that the adverse effects of alcohol on breast cancer risk might be ameliorated by adequate intake of folate from dietary sources alone'

To read the full paper and view a full list of references, see Journal of the National Cancer Institute, Vol 92, No3 February 2 2000 pages 266-269

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