Diet, lifestyle, and menstrual activity.

Menstrual activity is dependent on a critical body weight and may, therefore, be modified by nutritional factors. Lower plasma levels of testosterone, androstenedione, dehydroepiandrosterone, and prolactin, and differences in gonadotrophin levels were found during the menstrual cycle in rural black South African versus white women. When premenopausal vegetarian South African black women were fed a Western diet, plasma testosterone and prolactin levels increased, while estradiol decreased and follicle-stimulative hormone increased. In postmenopausal black women a similar diet decreased plasma leutinizing and follicle-stimulating hormone and increased prolactin levels. Differences between white and black women eating their customary diets may be related to genetic factors and/or lifestyle and diet. However, a Western diet induced changes in hormonal activity in vegetarian black women. These changes in hormonal levels in black women were comparable to those found in women with menstrual irregularities. Further study is needed to determine whether the difference in hormonal activity during the menstrual cycle between vegetarian black and white women may in part explain the lower incidence of coronary heart disease and breast cancer in the former.