How does caffeine consumption affect estrogen levels? One study revealed intriguing insights into how daily coffee habits might impact hormonal balance.
Asian American women who consumed an average of 200 milligrams or more of caffeine a day — the equivalent of roughly two cups of coffee — had elevated estrogen levels when compared to participants who consumed less, according to a study of reproductive-age women featured in the American Journal of Clinical Nutrition.
However, white women who consumed 200 milligrams or more of caffeine a day had slightly lower estrogen levels than participants who consumed less. Black women who consumed 200 milligrams or more of caffeine a day had elevated estrogen levels, but this increased amount was not enough to be statistically significant.
Total caffeine intake was calculated from coffee, black tea, green tea, and caffeinated soda. Findings differed slightly when the source of caffeine was considered individually. Consuming 200 milligrams or more of caffeine from coffee mirrored the findings for overall caffeine consumption, with Asian American participants having elevated estrogen levels, white women having lower estrogen levels, and the results for Black women were not statistically significant. However, consumption of more than one cup per day of caffeinated soda or green tea was associated with a higher estrogen level in Asian women, Black women, and white women.
The changes in estrogen levels among the women who took part in the study did not appear to affect ovulation. Previous studies suggested that caffeine might interfere with ovulation.
"The results indicate that caffeine consumption among women of child-bearing age influences estrogen levels," said Enrique Schisterman, PhD, of the Division of Epidemiology, Statistics and Prevention Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institute of Health.
"Short-term, these variations in estrogen levels among different groups do not appear to have any pronounced effects. We know that variations in estrogen levels are associated with such disorders as endometriosis, osteoporosis, and endometrial, breast, and ovarian cancers. Because long-term caffeine consumption has the potential to influence estrogen levels over a long period of time, it makes sense to take caffeine consumption into account when designing studies to understand these disorders."
The study authors noted that 89% of U.S. women from ages 18 to 34 consume the caffeine equivalent of 1.5 to two cups of coffee a day.
