Androst-4-ene,3,6,17-trione (6-0XO)

Androst-4-ene,3,6,17-trione (6-0XO)

syn. 4-Etioallocholen-3,6, 17-Trione
syn. 6-oxo-androstenedione


Combined 8
Clinical Support Rating 3
Empirical Evidence Rating 5

Androst-4-ene,3,6,17-trione (6-OXO) is a naturally-
occurring metabolite/intermediary in androgen
biosynthesis. Although no primary dietary source of this compound has been identified, it is found in trace amounts in some animal products. It has not been shown to have a necessary biological function, and is not considered an essential dietary nutrient. In humans, 6-OXO has been shown to inhibit the aromatase enzyme, which is responsible for converting testosterone and certain other steroid hormones to estrogens (such as estradiol and estrone). 6-OXO is
widely sold in sports nutrition, where it is promoted to increase testosterone levels and augment the anabolic effects of resistance training in men.
6-OXO is classified as a Type-I inhibitor of aro-
matase… It irreversibly binds the aromatase enzyme, preventing it from interacting with steroid hormones and producing estrogen. This can significantly increase serum testosterone levels by two mechanisms.
First, feedback inhibition of testosterone biosynthesis from estrogen is reduced (the brain reads high estrogen as a sign of high testosterone). Second, less free testosterone will be metabolized to estrogens, and thus left intact. Since testosterone is a strongly anabolic (muscle-tissue building) hormone in humans,
an increase in its levels might support an increase in muscle mass and strength. The ergogenic benefits of testosterone increases within or near normal levels, however, remain speculative. At the doses studied and recommended (300-600 mg per day), 6-OXO exhibits an incomplete level of aromatase inhibition. Estrogen levels tend to remain relatively stable (or even increase slightly) during
treatment. This may be due to a new homeostatic balance being reached, with lower levels of aromatase being countered by increased availability atizable substrates.
Since estrogen has been shown to
play a beneficial role with regard to the management of serum lipids and cardiovascular disease risk, and aromatase inhibition with other drugs has been shown to negatively alter cholesterol levels in men,” significant estrogen suppression may actually not be as de-
Studies also suggest that 6-OXO can increase steroid metabolism by the 5-alpha reductase enzyme. This enzyme is responsible for converting testosterone to a more androgenic metabolite (dihydrotestosterone) in various androgen responsive target tissues such as
the skin, scalp, and prostate. While DHT is speculated to impart beneficial effects with regard to exercise performance, it also is linked to the unwanted androgenic effects of steroid therapy (such as acne and male pattern hair loss). There have been, however, no reports in the cited clinical studies of significant androgenic side effects. The net metabolic effect of the
DHT increase with 6-OXO remains unclear.
Clinical studies support the use of 6-OXO to increase free testosterone levels in recreationally-active men. Given the known importance of testosterone the muscle anabolic process, it is speculated that 6-OXO
can increase the rate of muscle accumulation in response to regular resistance exercise. While clinical studies have not evaluated the effects of this supplement on exercise performance, empirical evidence seems to strongly support such use. Further research is needed to confirm, and better understand, the potential ergogenic properties of 6-OXO.

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