A woman’s responses and reactions to caffeine consumption may differ from a man's, especially in the way caffeine interacts with hormones, the menstrual cycle, and other body functions. Caffeine may also affect the endocrine, renal and nervous systems. Both women and men may experience common side effects associated with caffeine, such as nervousness, wakefulness, dizziness, nausea and irritability.
Scientific studies examining the effects of caffeine on women have yielded conflicting results, suggesting that more research is required to determine how caffeine affects women at various life stages.
Although research in the 1980s and 1990s suggested a correlation between caffeine consumption and fibrocystic breast disease, the Fact Sheet on Women’s Health presented in 2010 on the Food Insights website refutes those findings. Both the National Cancer Institute and the American Medical Association's Council on Scientific Affairs have stated there is no association between caffeine intake and fibrocystic breast disease. Nevertheless, some women report that reducing or eliminating caffeine helps relieve fibrocystic breast pain.
Psychiatric side effects from consuming too much caffeine range from mild confusion to serious psychotic symptoms. Caffeine may also increase anxiety and influence panic disorders in women.
Scientists disagree whether or not caffeine has a negative affect on bone density in women, according to two studies reported on the websites of the "American Journal of Clinical Nutrition" and the "Journal of the American College of Nutrition." A 1994 Tuft’s University study on the effects of caffeine consumption on bone mineral density in postmenopausal woman found that bone loss may be affected more by calcium intake in conjunction with caffeine consumption than by caffeine consumption alone. Women who consumed caffeine along with higher amounts of calcium suffered less bone loss than women who consumed caffeine with a lower calcium intake.
A study published in 2000 examining the effects of caffeine on bone loss in postmenopausal women concluded there was no association between caffeine consumption and bone density or bone loss.
On the website, womentowomen.com, OB/GYN nurse practitioner Marcelle Pick explains that caffeine may mask an adrenal imbalance that prevents restful sleep, which makes it harder for women to wake up. Although caffeine itself may not be the cause of adrenal fatigue, excess caffeine can cause body changes that stress the adrenal glands and also affect their ability to maintain sex hormone levels as women transition into menopause.
A study published in a 2007 issue of "Neurology" looked at thousands of women who consumed 3 or more servings of caffeine daily and found that caffeine significantly reduced cognitive decline in these women. This effect of caffeine was more significant in older versus younger women and was more beneficial for preventing verbal retrieval deficits than improving visuospatial memory. Caffeine from both coffee and tea had similar benefits in reducing cognitive decline in women.
According to a Kaiser Permanente news release, a study that followed over 1,000 pregnant women from 1996 through 1998 presented evidence that heavy caffeine use during pregnancy may increase the risk of miscarriage. De-Kun Li, MD, Ph.D., lead researcher on the study, said that women who consumed two or more cups of regular coffee or five 12-ounce cans of caffeinated soda daily had twice the risk of miscarriage compared to women who consumed no caffeine.
A 2010 review of epidemiologic literature from 2000 to 2009 discovered that evidence does not support a cause-and-effect relationship between caffeine consumption and negative perinatal outcomes.