An interesting new study on coffee shows that drinking coffee can alter estrogen levels in women and what is most surprising is that the impacts vary by race.
Coffee appears to lower estrogen in white women, but tends to raise the levels in Asian women. These effects appear to be so minimal that they have no real impact on healthy women. However, this study does help to understand how caffeine is metabolized by different genetic groups. The study was published in The American Journal of Clinical Nutrition and studied women aged 18-44.
On average, these women consumed 90 mg of caffeine per day, about the amount in one cup of coffee. About 90% of women in this age group drink the caffeine equivalent of 1-2 cups of coffee per day! It seems these effects were linked only to the caffeine in coffee and not with other types of caffeinated beverages. Other factors probably also play a role in that than just caffeine, like adding cream and sugar, or the amount of antioxidants in the drink.
Short-term, healthy women don’t need to worry about caffeine intake, especially given the health benefits of coffee. More research is needed to track these effects over many years.