Estrogen Changes Linked to Caffeine Consumption Show Racial Differences
The majority of women in the U.S. drink approximately 2 cups of coffee per day during their reproductive years. A recent study looking at estrogen levels and caffeine consumption shows that it’s not only what caffeinated beverage you drink, but also your race in conjunction with the beverage, that has an effect on your estrogen levels. Read on and discover the relationship between caffeine, estrogen and race.
Variations in estrogen levels are known to be linked to medical disorders such as endometriosis, osteoporosis, and endometrial, breast and ovarian cancers. With that in mind, caffeine is one common dietary factor that the majority of women consume on a daily basis throughout their reproductive years and is believed to have a potential influence on their estrogen levels.
As such, researchers from the National Institutes of Health and a number of other academic research institutions worked together on a study that was recently published in the American Journal of Clinical Nutrition. Their results from the study assessed the relationship between caffeine and estrogen in premenopausal women and evaluated the potential effect by race to see if racial differences played a role.
The study consisted of over 250 women ages 18 to 44 who on average consumed approximately 90 milligrams of caffeine (about the amount of caffeine in one cup of regular coffee) per day. The estrogen levels of the participants of the study were monitored multiple times each throughout two menstrual cycles. They were also given questionnaires regarding exercise, sleep, smoking and other lifestyle aspects as well as the types of meals they had eaten during the study.
What the researchers found was that Asian women who drank the caffeine equivalent of 2 cups of regular coffee (200 mg caffeine) had higher estrogen levels in comparison to women who consumed less caffeine. However, white women who 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.
One other interesting finding was that when the effects on estrogen based on the source of caffeine (coffee, caffeinated soda, green tea and black tea) were analyzed singularly, that the source and amount of caffeine altered the results some.
The researchers found that drinking 2 cups of coffee replicated the aforementioned results. However, when the source of caffeine was less (100 mg of caffeine) and from green tea or caffeinated soda, then the estrogen levels were elevated in all three races of women.
However, it should be noted that the changes in estrogen levels among the women who took part in the study did not appear to affect ovulation. This is in comparison to previous animal studies that suggest that caffeine might interfere with ovulation.
"The results indicate that caffeine consumption among women of child-bearing age influences estrogen levels," says Enrique Schisterman, Ph.D., of the Division of Epidemiology, Statistics and Prevention Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the NIH institute where some of the research was conducted. "Short term, these variations in estrogen levels among different groups do not appear to have any pronounced effects,” she stated in a press release from the NIH.
The researchers concluded that moderate consumption of caffeine was associated with reduced estradiol concentrations among white women, whereas caffeinated soda and green tea intakes were associated with increased estradiol concentrations among all three races. They believe that their results warrant further research to understand the effect caffeine consumption has on estrogen and other reproductive hormones and the link to racial differences.
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1. “Caffeinated beverage intake and reproductive hormones among premenopausal women in the BioCycle Study” American Journal of Clinical Nutrition February 2012 vol. 95; K. Schliep, E. Schisterman, S. Mumford, A. Pollack, C. Zhang, A. Ye, J. Stanford, A. Hammod, C. Porucznik and J. Wactawski-Wende.
2. NIH press release