Estrogen, Not Testosterone That Creates Libido In Women
Previous efforts to boost libido in women have wrongfully focused on boosting testosterone.
However, new research by James Roney and Zachary Simmons working out of UC Santa Barbara, have found that testosterone is not the main actor in driving women’s sexuality. Rather, it is estrogen.
Specifically, estrogen cycles in women, peaking right around the middle of a woman’s menstrual cycle which coincides with highest fertility at around ovulation. The rest of the cycle is spent in low estrogen, but higher progesterone. Naturally, progesterone functions as an antigen to sex drive serving to diminish sexually seeking behaviour.
“We found two hormonal signals that had opposite effects on sexual motivation,” said Roney. “Estrogen was having a positive effect, but with a two-day lag. Progesterone was having a persistent negative effect, both for current day, day before, and two days earlier.”
As progesterone increased, it mediated a drop in sexual desire and followed the fertility window occurring in the second half of the menstrual cycle.
“Progesterone acting as a potential stop signal within cycles is a novel finding in humans,” said Roney. “We know in rhesus monkeys there is a strong negative correlation with progesterone and a positive correlation with estrogen. The patterns are actually comparable to what you see in non-human primates, but hadn’t been shown in humans.”
While many doctors focus on replacing testosterone in women who have suffered a decline in sex drive, and in some cases, with good results, it’s likely not the entire story. The researchers note that when testosterone is given to women in high quantities, the body works to convert it through various enzymes into estrogen.
In other words, he says that “If you inject menopausal women with testosterone, it might be acting as a device that’s delivering estrogen to the target cells. So the fact that it works doesn’t necessarily mean it’s an important signal in the natural cycle.”
Roney, James R., Zachary L. Simmons. Hormonal predictors of sexual motivation in natural menstrual cycles. Hormones and Behavior. 2013; 63 (4): 636 DOI: 10.1016/j.yhbeh.2013.02.013