Effects of moderate alcohol consumption on folate and vitamin B12 status in postmenopausal women

Background: Although alcohol intake has been positively associated with breast cancer risk in epidemiologic studies, a causal relationship has not been established, and the mechanisms mediating this association are speculative. Alcohol may act through altered status of folate and vitamin B-12, two vitamins required for DNA methylation and nucleotide synthesis, and thus cell integrity. Although the effects of heavy alcohol intake on folate and vitamin B-12 status have been well-documented, few studies have addressed the effects of moderate alcohol intake in a controlled setting. Objective: The objective of this study was to determine the effects of moderate alcohol intake on folate and vitamin B-12 status in healthy, well-nourished, postmenopausal women. Design: The study design was a randomized, diet-controlled crossover intervention. Postmenopausal women (n=53) received three 8-week alcohol treatments in random order: 0, 15, and 30 g/day. Treatment periods were preceded by 2-5-week washout periods. Blood collected at baseline and week 8 of each treatment period was analyzed for serum folate, vitamin B-12, homocysteine (HCY), and methylmalonic acid (MMA) concentrations. Results: After adjusting for body mass index (BMI), a significant 5% decrease was observed in mean serum vitamin B-12 concentrations from 0 to 30 g of alcohol/day (461.45+/-30.26 vs 440.25+/-30.24 pg/ml; P=0.03). Mean serum HCY concentrations tended to increase by 3% from 0 to 30 g of alcohol/day (9.44+/-0.37 vs 9.73+/-0.37 mumol/l; P=0.05). Alcohol intake had no significant effects on serum folate or MMA concentrations. Conclusions: Among healthy, well-nourished, postmenopausal women, moderate alcohol intake may diminish vitamin B-12 status. Sponsorship: NCI, NIH and ARS, USDA.