In yet another analysis of the long-running Nurses Health Study, researchers have found that caffeine appears to have an impact on the production of different sex hormones in women.
By analyzing the survey data provided by over 1,200 women and pairing it with hormonal testing done on blood samples taken throughout the duration of the study, the folks at Harvard Medical School have been able to correlate a higher intake of caffeine to a decreased level of estrogen in premenopausal women in the latter half of their menstrual cycles. Similarly, in postmenopausal women, they tracked higher levels of sex hormone-binding globulin, which is known to decrease different levels of estrogen and testosterone in the system.
But what these discoveries portend is unclear; unrelated studies have previously linked high caffeine intake and high levels of estrogen and progesterone to ovarian and breast cancers in pre-menopausal women, but if caffeine is reducing the hormone levels in this group of women, then why would it be a possible carcinogen? The study’s authors indicate that further research should be undertaken to make this relationship more clear.