As you get older, wellness experts are likely to blame your waning testosterone levels for your loss of muscle, energy and sex drive, but oestrogen might be getting off scot-free as a result. This is according to a new study, published in The New England Journal of Medicine, which found that your decrease in oestrogen may play a bigger role in your age-related health concerns than previously thought.
The study found that declining levels of oestrogen can have a negative effect on your wellbeing, leading you to accumulate more body fat – which is something that we previously blamed testosterone for. Study researcher Dr. Joel Finkelstein, an endocrinologist at Massachusetts General Hospital in Boston, commented, ‘The function of oestrogen in men has largely been ignored,’ as research has largely limited the study of the hormone in men to the role of oestrogen deficiency in bone loss. He added, ‘Men make oestrogen from testosterone, and women do, too,’ which is why your levels of both hormones naturally drop.
400 healthy men aged 20 to 50, all of whom had normal testosterone levels, took part in the study. These participants were injected with a drug that drastically lowered their normal production of the hormone, until the testosterone reached pre-puberty levels of production. 198 men were then given a 16-week supply of testosterone gel for their skin, in one of four dosage levels or a placebo. Similar doses of the gel were given to the other 202 volunteers, but these men also took a drug designed to block the conversion of testosterone into oestrogen over the 16-week study.
The divvying out of the gel and drug doses was arranged in such a way as to tell the researchers which symptoms – changes in body fat, muscle mass, strength and sexual function – were to do with reductions in testosterone, oestrogen or both. The researchers also arranged the study in this way to determine the level of testosterone at which these physiological effects occur. The results revealed that when oestrogen levels drop, men experience some of the same consequences that women do after menopause; increased bone loss, lowered libido, and more fat around the midsection.
While changes in strength and muscle mass and size were closely connected to lower testosterone levels, it was the decline of both testosterone and oestrogen that reduced the men’s sex drive and erectile function. Finkelstein noted, ‘We were surprised at the dramatic effects that low levels of oestrogen had on fat accumulation and sexual function in men. We knew that these effects were seen in studies on mice, and these results very accurately predicted what occurred in humans.’
According to Dr. Bradley Anawalt, an endocrinologist and professor of medicine at the University of Washington Medical School in Seattle, who was not involved in the research, ‘This is a beautifully done study that allows physicians to get a little better handle on interpreting testosterone levels, but the real mind-blower of this study is the idea that oestrogen has an important role in male physiology.’ Anawalt went on to say that the study has very important implications for medical practice, as the results clearly show how testosterone has a differential effect on body organs, such as fat, muscle, the penis and the brain.
With the results of this study, your doctor will be better able to understand the threshold levels of testosterone in the blood associated with age-related complaints, and at what levels testosterone therapy may benefit you. However, Anawalt warned that the study is limited by the fact that it used the average “normal” level of testosterone in men (300 to 900 nanograms per decilitre) to measure treatment outcomes in the participants, so your doctor needs to be careful about applying these results to you as an individual.