As for Fibrocystic Breast Disease, the evidence isn't quite as clear, but it's still fairly conclusive. The aforementioned National Cancer Institute study showed no association between caffeine and benign tumors or breast tenderness, and the AMA's Council on Scientific Affairs says there's no connection. In addition, some women with fibroids who participate in the caffeine-related discussion groups on the Internet feel that abstaining from caffeine allieviates their symptoms. We have no medical evidence to back this up, but it works for them and you might want to see if it helps you. The latest word from the International Agency for Research on Cancer and the American Cancer Society is that there's no evidence relating moderate caffeine intake to any kind of cancer.
Some studies suggest that caffeine does cause bone loss.
But a 1994 study in the Journal of the American Medical Association looked at postmenopausal women and found no association between a lifetime of drinking 2 cups of coffee a day and reduced bone density, among women who drank one cup of milk a day during adulthood. A 1992 study of 290 white women of different ages in Rochester, MN found that moderate caffeine consumption wasn't an important risk factor for osteoporosis. And a small 1991 study of both vegetarian and non-vegetarian women, reported in the Journal of Clinical Nutrition, found no association between bone density and caffeine intake. Surprise, surprise, most studies on heart disease involve men. But a recent Scottish Heart Health Study surveyed over10,000 men and women, ages 40-59, and found no link between coffee and heart attacks.