Alcohol consumption and urinary concentration of 6-sulfatoxymelatonin in healthy women

Consumption of alcoholic beverages may suppress circulating melatonin level s at night, possibly resulting in an increase in circulating estrogen. An i ncreased estrogen burden could increase the risk of breast cancer. This stu dy was designed to investigate whether alcohol consumption is associated wi th a decrease in nighttime melatonin levels in a group of healthy women. A total of 203 randomly selected healthy women between the ages of 20 and 74 years were recruited for a broader study of the effects of exposure to powe r-frequency magnetic fields on nocturnal levels of urinary 6-sulfatoxymelat onin. FOE. the purposes of this analysis, data collection consisted of the following during two seasons of the year: CI) an in-person interview, (2) a dairy activity diary, and (3) nocturnal urine collection for each of 3 con secutive nights. We found that the nocturnal urinary concentration of the p rimary metabolite of melatonin (6-sulfatoxymelatonin) decreased in a dose-d ependent manner with increasing consumption of alcoholic beverages in the p receding 24-hour period, after taking into account the independent effects on melatonin of age, hours of darkness, use of medications that affect mela tonin levels, and body mass index. A categorical analysis revealed no effec t of one drink, but a 9% reduction with two drinks, a 15% reduction with th ree drinks, and a 17% reduction with four or more drinks. It remains unknow n whether such a change could affect estrogen levels or breast cancer risk.