<p>Your daily dose of caffeine may tinker with more than just your energy levels. A new study of women, ages 18 to 44, found that drinking coffee and other caffeinated beverages can alter levels of estrogen. <br /><br /></p>.<p>But the impact varies by race. In Asian women it has the reverse effect, raising levels of the hormone.<br /><br />The study did not look at older women, but women of child-bearing age who enjoy a daily cuppa have little reason to fret, the researchers said. The effects of caffeine on estrogen are so minimal that in healthy women, it has no impact on ovulation or overall health, at least in the short term.<br /><br />“This is important physiologically because it helps us understand how caffeine is metabolised by different genetic groups,” said Dr Enrique Schisterman, an author of the study and senior investigator at the National Institutes of Health. “But for women of reproductive age, drinking coffee will not alter their hormonal function in a clinically significant way.”<br /><br />The study, which was published in The American Journal of Clinical Nutrition, analysed data on more than 250 women. They provided blood samples along with details about behaviours like exercise, eating and smoking. On average, they consumed about 90 milligrams of caffeine a day, equivalent to roughly one cup of coffee.<br /><br />Asian women, those who had 200 milligrams or more of caffeine a day, had higher estrogen levels compared to those who consumed less. A similar pattern was seen among black women, though it was not statistically significant. In white women, however, 200 milligrams or more of caffeine appeared to have a slight lowering effect on estrogen.<br /><br />Why caffeine would have a different impact depending on race was unclear, though Dr Schisterman said it was likely that genetics has an influence on caffeine metabolism. The source of caffeine also seemed to make a difference. <br /><br />When the researchers looked exclusively at caffeine from beverages other than coffee — like green tea and soda — it was linked to higher estrogen in all women, regardless of race. Various levels of antioxidants and additives like milk and sugar, might play a role, he said. Dr Schisterman noted that while healthy, premenopausal women should not worry about caffeine intake Nicolas Bakalar<br /></p>
<p>Your daily dose of caffeine may tinker with more than just your energy levels. A new study of women, ages 18 to 44, found that drinking coffee and other caffeinated beverages can alter levels of estrogen. <br /><br /></p>.<p>But the impact varies by race. In Asian women it has the reverse effect, raising levels of the hormone.<br /><br />The study did not look at older women, but women of child-bearing age who enjoy a daily cuppa have little reason to fret, the researchers said. The effects of caffeine on estrogen are so minimal that in healthy women, it has no impact on ovulation or overall health, at least in the short term.<br /><br />“This is important physiologically because it helps us understand how caffeine is metabolised by different genetic groups,” said Dr Enrique Schisterman, an author of the study and senior investigator at the National Institutes of Health. “But for women of reproductive age, drinking coffee will not alter their hormonal function in a clinically significant way.”<br /><br />The study, which was published in The American Journal of Clinical Nutrition, analysed data on more than 250 women. They provided blood samples along with details about behaviours like exercise, eating and smoking. On average, they consumed about 90 milligrams of caffeine a day, equivalent to roughly one cup of coffee.<br /><br />Asian women, those who had 200 milligrams or more of caffeine a day, had higher estrogen levels compared to those who consumed less. A similar pattern was seen among black women, though it was not statistically significant. In white women, however, 200 milligrams or more of caffeine appeared to have a slight lowering effect on estrogen.<br /><br />Why caffeine would have a different impact depending on race was unclear, though Dr Schisterman said it was likely that genetics has an influence on caffeine metabolism. The source of caffeine also seemed to make a difference. <br /><br />When the researchers looked exclusively at caffeine from beverages other than coffee — like green tea and soda — it was linked to higher estrogen in all women, regardless of race. Various levels of antioxidants and additives like milk and sugar, might play a role, he said. Dr Schisterman noted that while healthy, premenopausal women should not worry about caffeine intake Nicolas Bakalar<br /></p>