Caffeine affects estrogen levels, but health outcomes remain unknown
By Maria Cendejas
A new study says caffeine changes the estrogen levels in women and it has different effects in Asian women and white women, according to USAtoday.
Estrogen, a reproductive hormone created by the ovaries, is promoting breast cancer and other reproductive cancers in women. The study suggests that drinking coffee may change the risk for the diseases.
More than 250 women, ages 18 to 44, took part in the study between 2005 and 2007. On average, the women had intake of 90 milligrams of caffeine a day.
Asian women who consumed an average of 200 milligrams or more of caffeine a day had high estrogen levels, compared to those who consumed less. But white women who consumed the same amount of caffeine had slightly lower estrogen levels than women who consumed less.
Black women who consumed 200 milligrams or more of caffeine on a daily basis had high estrogen levels. But this difference wasn't statistically significant, said the U.S.National Institutes of Health researchers.
In the study, the women might consume caffeine from any of these sources: coffee, black tea, green tea and caffeinated soda. The findings were a little different when the researchers considered the source of caffeine independently.
Consuming 200 milligrams of coffee mirrored the overall findings. But consumption of more than one cup each day of caffeinated soda or green tea was associated with higher estrogen in all three groups of women, according to the study published online in the February issue of the American Journal of Clinical Nutrition.
The researchers said that the caffeine-related changes in estrogen levels didn’t appear to affect women's ovulation. They followed the women for up to 2 menstrual cycles.
According to the authors, about 89% of U.S. women from ages 18-34 consume at least two cups of coffee a day.
"The results indicate that caffeine consumption among women of child-bearing age influences estrogen levels," Enrique Schisterman, of the Division of Epidemiology, Statistics and Prevention Research at the U.S. National Institute of Child Health and Human Development, said in an NIH news release.
"Short term, these variations in estrogen levels among different groups do not appear to have any pronounced effects. We know that variations in estrogen level 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," Schisterman said.