The theory of enhancing testosterone for better sexual function
Testosterone and estrogens are, to a certain extent, metabolically linked. Estradiol, the most potent of the estrogens, is synthesized in the body by the enzyme aromatase from testosterone. Furthermore, while they do not bind to androgen receptors, estrogens and androgens compete for influence within the endocrine system. Depending on the specific receptor sites, a single hormone can have diverse effects. The body furthermore possesses a full arsenal of mechanisms by which certain hormones can be rendered inactive. They can be bound by carrier proteins and up- or down-regulated by other hormones.
Because our knowledge of the endocrine system is far from complete, there are many scenarios in which intended results are not achieved.
You may, for example, supply exogenous testosterone, and much of it is converted into estradiol. You actually end up with a balance that is more tilted towards estrogen than it was when you started the supplementation.
Or you may overly inhibit aromatase, only to find that libido relies heavily on specific estrogen and androgen receptor activation in the brain. According to such a scenario, you would gain little from extreme aromatase inhibition, as some estradiol is physiologically required for male libido. The task would then be to properly modulate those receptor sites rather than simply eliminating estrogen.
The above paragraphs illustrate that the influence of hormones on libido and sexual function is complex, and outcomes can be unpredictable.
The evidence that testosterone is a primary hormone of desire exists largely in reverse: if you severely inhibit testosterone production, you can reliably diminish libido.
Nevertheless, the key to maintaining sexual health is likely hormonal. It is just that the exact mechanisms by which hormones determine libido and sexual function are not entirely straightforward. One thing is clear: exogenous testosterone does not work by a simple linear formula where slightly more testosterone equals slightly more libido, and much more testosterone equals much more libido.
That would be too simple to be true.
On the other hand, if you do nothing to support your endocrine health, your libido will likely decline significantly as you age. If it is already diminished or clearly declining, you may consider exploring hormonal modulators, even though definitive protocols for optimization are still evolving.
Because theoretical knowledge about the endocrine system is incomplete, a clinical, evidence-based approach is best. Look for information on what has worked in clinical practice, rather than relying solely on theories of why a specific intervention should work.
Currently, a popular option for improving libido and potentially supporting testosterone levels is the Southeast Asian herb Tongkat Ali (Eurycoma longifolia). This root has been used as an aphrodisiac in Southeast Asia and traditional Chinese medicine long before scientific studies showed it could influence testosterone levels. However, the fact that Tongkat Ali is used as an aphrodisiac and may raise testosterone does not strictly mean it works as an aphrodisiac because it raises testosterone. Herbal supplements typically contain dozens of active compounds, many of which have not yet been fully studied. It may be that one component of Tongkat Ali influences testosterone, while another acts on libido through a different pathway.
Nevertheless, it is evident that maintaining the sexual vitality of a 20-year-old at an older age requires supporting the endocrine system.
An initial guideline is that if we want the sexual health profile of a younger man, we should aim for a similar hormonal balance. Generally, this means optimizing free testosterone, managing estradiol levels, minimizing excess sex hormone-binding globulin (SHBG), and regulating aromatase activity.
Current endocrinology indicates that the primary goal for a man around 50 is often to optimize free (bioavailable) testosterone.
To achieve optimal testosterone levels, a few physiological factors must be kept in mind.
First, the supplementation of pharmaceutical testosterone by itself may not always yield the desired results. There can be a tendency for exogenously supplied testosterone to bind to sex hormone-binding globulin (SHBG), rendering it biologically inactive rather than circulating as free testosterone.
Furthermore, the body converts testosterone into estradiol, the most potent of the estrogens. ("Estrogen" is not the name of a single hormone but a class of hormones; the equivalent class is "androgen." Within these classes, the direct physiological equivalent to testosterone is estradiol).
The conversion of testosterone into estradiol is catalyzed by the enzyme aromatase, and this process can occur in various tissues throughout the body, including adipose (fat) tissue.
There is a distinct possibility that supplying the body with exogenous testosterone will not have the desired effect, even if it remains bioavailable, because the body may simply convert this excess testosterone into estradiol. The resulting effect may be the opposite of what was intended, leaving the testosterone-to-estradiol ratio more tilted toward estrogen than before supplementation.
In some clinical scenarios, managing aromatase activity is considered before or alongside testosterone optimization.
Aromatase inhibitors can block the enzyme responsible for estradiol conversion. One highly specific non-steroidal aromatase inhibitor is anastrozole (Arimidex).
However, not all low testosterone states are caused by excess aromatase activity. It could simply be that the Leydig cells in the testicles are not sufficiently stimulated to produce enough testosterone. Stimulating the production of endogenous testosterone may be preferable to supplying exogenous testosterone, which can suppress natural production and sometimes fail to improve libido.
The body’s own synthesis of testosterone begins deep in the brain, in the hypothalamus. The hypothalamus secretes gonadotropin-releasing hormone (GnRH).
This hormone stimulates the pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH then stimulates the Leydig cells in the testicles to produce testosterone. In women, these hormones stimulate the ovaries.
The hypothalamus and pituitary gland are not gender-specific, and there are medications that can be used to stimulate this axis. Clomiphene citrate (Clomid) is one example. In women, the medication is used to induce ovulation and restore fertility. It is so effective that roughly 8 to 10 percent of Clomid-induced pregnancies result in twins.
Bodybuilders who have suppressed their natural testosterone production through the heavy use of anabolic steroids often use Clomid as part of post-cycle therapy to restart endogenous production, and clinical evidence supports its efficacy for this purpose.
Clomiphene citrate is a selective estrogen receptor modulator (SERM). It not only stimulates the hypothalamus but also exerts anti-estrogenic effects in certain tissues. By binding to estrogen receptors, clomiphene citrate blocks the stronger estradiol from occupying those specific sites.
However, while the mechanism of clomiphene citrate suggests it should reliably raise testosterone and enhance libido, scientific studies have shown mixed results regarding its ability to improve sexual desire, despite successfully increasing serum testosterone levels in many men.
While Tongkat Ali extract is one of the few herbal supplements shown to potentially support both testosterone levels and libido, there are also several reliable, non-pharmaceutical lifestyle methods to support healthy testosterone:
1. Maintain a healthy weight. Excess adipose (fat) tissue contains aromatase, which converts testosterone into estradiol, potentially lowering the free testosterone balance.
2. Exercise. A balanced program of regular resistance training and cardiovascular exercise can help optimize testosterone levels.
3. Engage in regular sexual activity. Research suggests a bidirectional relationship where regular sexual activity helps maintain healthy baseline testosterone levels compared to prolonged abstinence.
Whether these three lifestyle steps will drastically increase libido in every individual is less certain. It is evident that they are not a universal cure-all. Many 20-year-olds living a sedentary lifestyle have no problems with their libido, while some 50-year-olds who exercise regularly still struggle with sexual desire. Hormonal optimization is highly individualized.