Caffeine seems to be something to stay away from for me anyway due to the posibllity of it working on E2, and raising estrogen levels. Guess this would explain why drinking three cups of coffee daily has helped prevent OP in women.
Coffee Increases Estrogen in Women
Drinking more than two cups of coffee daily may boost estrogen levels in women and could worsen conditions such as endometriosis and breast pain.
According to the researchers, women who drank the most coffee had higher levels of estradiol, a naturally occurring form of estrogen, during the early follicular phase, or days 1 to 5 of the menstrual cycle.
Higher estrogen levels would not be beneficial for women who for example have endometriosis, breast pain and family histories of breast or ovarian cancer, especially arising premenopausally.
The study included nearly 500 women aged 36 to 45 who were not pregnant, breast-feeding or taking hormones. All women answered questions about their diets, smoking habits, height and weight. Researchers measured the women's hormone levels during days 1 to 5 of their menstrual cycle.
Women who consumed more than one cup of coffee a day had significantly higher levels of estrogen during the early follicular phase of their menstrual cycle.
Caffeine intake from all sources was linked with higher estrogen levels regardless of age, body mass index (BMI), caloric intake, smoking, and alcohol and cholesterol intake.
Women who consumed at least 500 milligrams of caffeine daily, the equivalent of four or five cups of coffee, had nearly 70% more estrogen during the early follicular phase than women consuming no more than 100 mg of caffeine daily, or less than one cup of coffee.
This study provides a basis for believing that coffee consumption increases estradiol levels. While these effects are modest with one or two cups, they are more evident at higher levels of consumption.