A study published by The American Journal of Clinical Nutrition found women between 18-44 had their estrogen levels altered when drinking coffee. Even though Women in child-bearing years had estrogen levels effected when drinking caffeinated beverages, their ovulation or overall health had no impact.
Researchers studied around 250 women between the ages of 18-44 and who consumed around 90 milligrams (one cup of coffee) of caffeine per day. Estrogen levels of the study members were checked one to three times a week over two menstrual cycles. They provided blood samples and also were give a questionnaire about exercise, sleep, smoking, meals and other lifestyle behaviors they may have.
The study found that Asian women who drank 2 cups of coffee (200 mg caffeine) had higher estrogen levels compared to women who consumed less caffeine. White women on the other hand, consumed the same amount of caffeine per day as Asian women, had lower estrogen levels than women who consumed less caffeine. Black women who consumed 200 mg of caffeine also had elevated levels of estrogen, but not elevated enough to be statistically significant for the number of women tested.
Dr. Enrique Schisterman, an author of the study and senior investigator at the National Institutes of Health said, “This is important physiologically because it helps us understand how caffeine is metabolized by different genetic groups. But for women of reproductive age, drinking coffee will not alter their hormonal function in a clinically significant way.”
So the question might be, why does caffeine have a different effect on race? Dr. Schisterman said it was likely that genetics has an influence on caffeine metabolism.
What’s even more interesting, researchers found that when the source of caffeine was less (100 mg of caffeine) and from a different caffeinated beverage, the estrogen levels were elevated in all three races of women. Researchers believe that various levels of antioxidants and other compounds in the drinks, as well as additives, might play a role as to why, Dr. Schisterman said.
Dr. Schisterman noted, “While healthy, premenopausal women should not worry about caffeine intake in the short term, more research is needed to see if there could be a cumulative impact over many years or decades. We don’t know if there are long-term effects of these small shifts in hormonal levels.”