The research showed that people with a particular genotype (MTHFR677, CC) tend to have slightly lower levels of homocysteine to begin with, but show less of a decline with increasing amounts of folate intake, than do people with the CT or TT versions. And, moderate drinkers (defined here as women consuming 15 g alcohol, or a little over one typical drink, per day) had the highest levels of homocysteine if they consumed low amounts of folate, but the strongest decrease if they consumed average or high levels of folate.
People with the CT and TT variants of the MTHFR677 gene have higher risk for coronary disease only if they have low folate intake. The authors state from their previous work that “Women with both high folate intake and moderate alcohol intake had a significantly lower risk of coronary disease than did nondrinkers with low folate intake.” They attribute this protection to be partially mediated through homocysteine. They also state that their previous work has shown that Alcohol intake significantly increases the risk of breast and colon cancer, although the association appears limited to persons with low folate intake. They suggest that these interactions in relation to cancer are not likely to be due to a biological effect of homocysteine but rather to the importance of folate on gene methylation, with aberrations in DNA methylation a potential risk factor for cancer.
A similar relation was recently reported by Baglietto et al for the relation between alcohol and breast cancer. The Australian study, followed 17,447 Melbourne women from 1990 to the end of 2003, by which time 537 had developed breast cancer.
The researchers found no link between breast cancer and folate consumption, But a diet rich in folate appears to mitigate the breast cancer risk associated with alcohol, Professor Graham Giles of Cancer Council Victoria and team reported “Women who had high alcohol consumption and low intake of folate had an increased risk of breast cancer, but those women who had high alcohol consumption and moderate to high levels of folate intake had no increased risk,”
The study didn’t look at the specific level of folate consumption that mitigated this risk, he says. But it found drinkers who consumed less than 200 micrograms of folate a day, or the equivalent of around 220 grams of leafy green vegetables, faced extra risks. English says folate plays a role in DNA regulation and is believed to help prevent genetic abnormalities that can cause cancer. For instance it can prevent genes from mutating or becoming silenced, he says. Alcohol, meanwhile, is converted by the body into the cancer causing toxin acetaldehyde, which destroys folate, thus stimulating cancer cell growth.
Director of the New South Wales Breast Cancer Institute, Professor John Boyages, who was not involved in the original research, says the study implies that alcohol increases the risk of breast cancer because of its impact on folate levels. But he says the risk of breast cancer from alcohol is around the same as early menstruation, late menopause or taking the contraceptive pill for a few years- i.e. low.
Neither study gave beverage-specific results. However, it is known that beer contains high levels of folate and other B vitamins, as do leafy veg, tomatoes and cereals. No one has yet suggested adding folate to wine or spirits.
Some studies have also suggested folate has a protective effect against colon cancer.
Source: Chiuve SE, Giovannucci EL, Hankinson SE, Hunter DJ, Stampfer MJ, Willett WC, Rimm EB. Alcohol intake and methylenetetrahydrofolate reductase polymorphism modify the relation of folate intake to plasma homocysteine. Am J Clin Nutr 2005;82:155 162. and Baglietto et al. Does dietary folate intake modify effect of alcohol consumption on breast cancer risk? Prospective cohort study.BMJ,doi:10.1136/