"Our findings suggest that it might be important for women taking estrogen after menopause to also take androgen supplements which can include testosterone," said Charles E. Wood, D.V.M., lead researcher, from Wake Forest University Baptist Medical Center. The research is reported in the current issue of The Journal of Clinical Endocrinology & Metabolism.
The adrenal glands are the primary source of androgen hormones in women. While aging is associated with a marked decline in androgens, others factors involved in adrenal androgen production are not well-known. Regulation of androgen levels may be particularly important in postmenopausal women because observational studies have shown that older women who have higher levels tend to be healthier.
"Recently, there has been increased interest in supplementing androgens in older women and research is underway to understand more about these hormones," said Wood. "Our study makes the point that estrogen reduces the adrenal gland's production of androgens."
Wood and colleagues studied both premenopausal and postmenopausal estrogen treatment and the effects on androgen levels in a large group of female cynomolgus monkeys. Half of the monkeys were given oral contraceptives, which contain estrogen, in their diets for 26 months. All animals then had their ovaries removed to make them menopausal.
For the next three years, the animals were divided into three groups based on diet. One group ate soy that didn't contain isoflavones, which are natural plant estrogens; one group ate soy with the isoflavones intact, and one group's diet was soy without isoflavones and Premarin, or estrogen therapy, added.