Pro-hormones are substances that can be converted into active hormones by specific enzymes in the body. Pro-hormone supplements are currently sold over the counter courtesy of the 1994 Dietary Supplement Act, which permits the sale of any naturally occurring substance that is considered safe until proven otherwise.
Although they were introduced just a few years ago, pro-hormone supplements have evolved considerably. The first one available was DHEA, a natural adrenal steroid. While DHEA offers several health benefits, particularly for those over 40 whose DHEA production is naturally declining, it proved problematic for younger men and women. In younger men oral DHEA supplements most often metabolize to androstenedione, another adrenal steroid and a direct precursor of testosterone synthesis. Unfortunately, androstenedione can take another pathway—into estrogen conversion—and that happened to a lot of young men who took DHEA. Ironically, androstenedione usually converts into testosterone in young and older women. On the other hand, it’s the major androgen produced in women’s bodies and the natural source for their testosterone synthesis.
When it became apparent that DHEA wasn’t the best pro-hormone for bodybuilding purposes—at least in men—androstenedione itself came on the market. That led to estrogen-based problems, including gynecomastia, or excess male breast tissue; water retention and increased subcutaneous fat deposits, meaning the fat that’s just under the skin.
The first truly successful pro-hormone in terms of testosterone conversion was called 4-androstenediol, or 4-AD. Some studies showed that it was at least three times more effective than androstenedione at converting into testosterone, and it appeared to produce fewer estrogen-related side effects. The major problem with 4-AD was that when people took it orally, about 85 percent of the dose was deactivated in the liver in a process called first-pass metabolism. That mandated an improved delivery system.
Patrick Arnold, the leading authority on pro-hormone metabolism and development, came up with the idea of using a cyclodextrin delivery system for pro-hormones. Coating the pro-hormone matrix with carbohydrate allowed it to be absorbed through the oral mucosa in a sort of Trojan-horse effect, bypassing first-pass liver metabolism. The technology had previously proven effective for actual testosterone-based drugs. The advantage of cyclodextrin pro-hormones was that you could not only absorb more of the supplement but also use lower doses, lessening the chance of side effects.
Since then other types of delivery systems have been introduced, such as transdermal (through the skin) delivery. More recently, Pat Arnold brought out 1-AD, which appeared to be the first truly effective pro-hormone supplement. Also called 1-testosterone, its advantages include no conversion into estrogen or problems with conversion into dihydrotestosterone (DHT), a testosterone metabolite that’s linked to such side effects as acne, male-pattern baldness and prostatic enlargement.
While 1-AD may justifiably be called the pick of the litter of currently available pro-hormone supplements, some problems are emerging. They aren’t directly related to 1-AD’s metabolic activity but rather issues such as quality control and proof of efficacy. No published study in any reputable medical journal has yet examined 1-AD’s anabolic efficacy. That doesn’t mean it doesn’t work as advertised, only that there’s no proof involving healthy human athletes. When such experiments were done on androstenedione, it turned out that andro was an effective pro-hormone—for converting into estrogen, not testosterone, in men.
A forthcoming study analyzed several popular supplements that are marketed to bodybuilders and other athletes.1 Among the supplements studied were a commercial version of 1-AD and an unidentified supplement that, judging by its contents, appears to be a thermogenic, or fat-burning, product. The fat burner turned out to be contaminated with various pro-hormones, including 19-nor, 4-AD and DHEA—and testosterone itself.