Variations in estrogen levels can affect women’s health in many ways, from monthly PMS and acne breakouts to more serious conditions such as endometriosis, osteoporosis and some cancers. So it’s important for women to know which lifestyle factors may affect estrogen levels.

A new study found that caffeine had different effects on estrogen levels that varied by caffeine source and the study participants ethnicity.

During the two year study, more than 250 women ages 18 to 44 consumed an average of 90 milligrams of caffeine a day. This is equivalent to one cup of caffeinated coffee.

Asian women who consumed about 200 milligrams or more of caffeine a day had elevated 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 had a slight, but statistically insignificant rise in estrogen levels with consumption of the same amount of caffeine.

Coffee vs. Tea

When the researchers considered the source of the caffeine: coffee, black tea, green tea or caffeinated soda, the findings differed slightly.

Caffeine from coffee mirrored the overall findings, but consumption of more than one cup each day of caffeinated soda or green teas was associated with higher estrogen in all three groups of women.

Health Implications

The caffeine induced changes in estrogen levels did not appear to affect women's ovulation, said the researchers, who followed the women for up to two menstrual cycles. However, the researchers are concerned about the long-term effects of caffeine consumption on women’s 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 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," Enrique Schisterman, of the Division of Epidemiology, Statistics and Prevention Research at the U.S. National Institute of Child Health and Human Development.

About 89 percent of U.S. women ages 18 to 34 consume the caffeine equivalent of 1.5 to two cups of coffee a day, according to the authors.

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Health Day

Exercise is good medicine that, not only, slows down stress-related aging at the cellular level and helps to reduce a man's prostate cancer risks, and lowers a woman's chances of developing endometrial cancer by as much as 30 percent, according to a new study.

Scientists arrived at that number based on an analysis of 14 previous studies that showed how exercise lowered a woman's odds of endometrial cancer, ranging from 20-40 percent. Although one study documented how vigorous 20-minute exercise sessions five days a week cut a female patient's risk of endometrial cancer by 20 percent, researchers shied away from making any blanket recommendations about exercise intensity or duration.

Experts weren't nearly as shy, however, in warning women about the health problems associated with being sedentary. In this dose-responsive analysis, a women who devoted at least nine hours each day to sitting doubled her chances of fighting endometrial cancer during her lifetime.

With colder weather on the way, it's best for your health to get started on an exercise program sooner rather than later.

British Journal of Cancer, Vol. 103, No. 7, p. 933-938, September 28, 2010 Free Full Text Study

USA Today October 1, 2010