Background: Heavy alcohol consumption is associated with menstrual irregularities, including anovulation, luteal-phase dysfunction, recurrent amenorrhea, and early menopause. In addition, moderate to heavy alcohol intake has been found to increase the risk of spontaneous abortions and breast cancer. These adverse effects could at least in part originate from alcohol-mediated changes in hormone levels.
Methods: The acute effect of alcohol on the hormone balance in women using oral contraceptives (OC+) and also in nonusers (OC-), was evaluated in 30 OC- and 31 OC+ subjects, representing the whole period of the menstrual cycle. It was also evaluated in 40 OC- and 47 OC+ subjects during the midcycle phase and in 10 OC+ subjects with unknown cycle phase.
Results: We found that among subjects who used oral contraceptives, estradiol levels increased and progesterone levels decreased after intake of alcohol (0.5 g/kg). No dose effect (0.34-1.02 g/kg) on progesterone was observed in a substudy on 10 OC+ subjects. With regard to estrone levels, no effect was observed, although a significant increase was found in the estradiol-to-estrone ratio. Among subjects not using oral contraceptives, progesterone levels decreased after intake of alcohol (0.5 g/kg). No effect was found in estradiol, estrone, or the estradiol-to-estrone ratio during midcycle in this study group. A transient elevating effect of alcohol (0.5 g/kg) on prolactin levels was observed in both study groups. We found that alcohol (0.5 g/kg) had no significant effect on luteinizing hormone (LH) levels among subjects not using oral contraceptives, and observed a decline among subjects using oral contraceptives at midcycle.
Conclusions: We suggest that the estradiol and progesterone effects are related to decreased steroid catabolism, resulting from the alcohol-mediated increase in the hepatic NADH-to-NAD ratio. The transient effect on prolactin levels may reflect acute changes in opioid and dopamine levels in the hypothalamus. The present findings regarding female sex steroids may be of relevance in the association between moderate to heavy alcohol consumption and the development of breast cancer.