According to a study done by the National Institutes of Health, there is an association between estrogen levels and caffeine consumption. The study looked at coffee drinking habits of women of Asian, white, and black descent.
Two cups of coffee a day (about 200 milligrams) resulted in elevated estrogen levels in Asian women. The same was true for black women. For the white women, however, the estrogen levels reduced with the same amount of coffee a day.
“The results indicate that caffeine consumption among women of child-bearing age influences estrogen levels,” shared Enrique Schisterman of the Division of Epidemiology, Statistics and Prevention Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) (via National Institutes of Health). This study also alludes to the fact that genetics play a role in how coffee consumption affects our bodies and how much coffee we can tolerate.