One category of dietary supplements that continues to experience controversy is the so-called prohormones or testosterone precursors. For purported muscle building enhancement these products typically contain DHEA (dehydroepiandrosterone) and Andro (androstenedione). Controversy aside, both Andro and DHEA are actually hormones made by the body. They are also the precursors of testosterone and estrogens.

In general there are two groups of males who are interested in increasing their testosterone levels: 1) young athletic adults; and 2) older adults. This interest in increasing testosterone levels is based on the fact that testosterone is the primary male hormone responsible for building and maintaining big muscles and masculinizing effects. Young males seek taking these testosterone boosters are driven by the "more is better" mind-set, while older males seek to restore normal youthful testosterone levels. Among females, testosterone is found in much lower levels, but also exerts anabolic and masculinizing effects if the levels are artificially increased. A review of the medical research will be helpful in leading to an objective viewpoint on the usefulness of these prohormone-testosterone boosting supplements for sports nutrition applications, sorting gym hype from scientific evidence.

DHEA is a steroid hormone produced mainly by the adrenal glands. In men, it is also produced in the testes as an intermediate in testosterone production, and in women, it is also produced in the ovaries as an intermediate in estrogen production. DHEA is weak androgen (a steroid hormone that promotes masculine characteristics), and it has been reported to induce growth of body hair in men and women. In a pilot study using men between the ages of twenty and twenty-five, supplemental DHEA did not increase testosterone levels but did appear to help decrease body fat and increase lean body mass. However, when this study was duplicated, no significant changes in body composition were observed. Conversely, in another study, an increase in androgen levels was reported in postmenopausal women given supplemental DHEA, as was an increase in body-hair growth during the study period. Another study, this one using both men and women, did not report any significant changes in lean body mass or body fat but did report an overall improvement in the feeling of well-being. This last study also reported a possible anabolic effect-an increase in the IGF-I level. IGF-I is an important growth promoter in muscles, especially in individuals undergoing intensive training.

Major studies with athletes taking DHEA supplements have not yet been reported. However, a small study with young weight lifting men (average age 23 years old), taking 50 mg of DHEA per day, did not report any improvements in strength and lean body mass when compared to the placebo group. Going by the results of the studies just mentioned, and other studies, medically unsupervised DHEA use by young male athletes probably won't increase testosterone levels significantly enough for stimulating benefits greater then those experienced by natural testosterone production. However, careful use by female athletes and male athletes over age forty may cause some beneficial physical and physiological effects. Other reported benefits of DHEA include immune-system enhancement, antidepressant action, enhancement of mental functioning, and longevity in laboratory animals. The amounts used in studies have varied, but benefits have been reported in the 25 to 100 milligram per day range, with 50 milligrams per day being reported safe for short-term use of several months. A word of caution: do not take supplemental DHEA if you are a man who may have prostate cancer or a woman who may have breast cancer, a reproductive cancer, or a reproductive disorder, and only use under doctor supervision.

Androstenedione has an equally dubious origin as it applies to sports nutrition. You will commonly encounter reference to a study conducted by V. B. Mahesh and R. B. Greenblatt used by Andro supplement companies to substantiate that Andro supplements are effective at boosting testosterone levels and promoting larger muscles and strength. You may be surprised to learn that the 1962 Mahesh study used only 4 nonathletic women. Furthermore the results of the study were based on one dose of either 100 mg of DHEA taken by two of the women or 100 mg of androstenedione taken by the other two women, lasting only several hours. Based on blood samples taken shortly after ingesting the DHEA and Andro supplements, both DHEA and Andro caused a temporary rise in the women's serum testosterone levels with Andro causing about double the rise in testosterone. Amazingly, during the 1990's, tales of this one day research study on two women taking Andro prompted androstenedione being marketed as a muscle-building supplement for male athletes, while no real proof existed that males would benefit from taking Andro. You will commonly encounter this scientific reference used in promotional literature as substantiation of Andro supplements (Mahesh, V.B. and R. B. Greenblatt. "The In Vivo Conversion of Dehydroepiandrosterone and Androstenedione to Testosterone in the Human." Acta Endocrinology, Vol. 41 (1962), pp. 400-406.) You now know that the study substantiates nothing as far as sports nutrition is concerned. Some Andro studies later conducted using males did not show a significant rise in testosterone levels or significant improvements in muscle size or strength.

While millions of andro tablets are consumed per day by iron pumping athletes, recent research adds to the disappointing news of previous studies. For example, a recent study looked at the effects of an androstenedione complex formula had on weight lifting males. The complex formula contained a daily dosage of 300 mg of androstenedione, plus, 150 mg of DHEA, 750 mg of Tribulus terrestris, 625 mg of chrysin, 300 mg of indole-3-carbinol, and 540 mg of Saw palmetto. Blood levels of androstenedione concentrations did increase in the supplement taking group when compared to the placebo group. During the 8 week study period, muscle strength was increased in both the groups, but the differences were not significant. The researchers also observed the use of the androstenedione complex formula did not result in increased serum testosterone concentrations. The increased production of estrogen caused by the androstenedione supplement was not reduced by the addition of chrysin. All told, the andro supplement did not cause additional benefits to resistance-training young adults.

One group of researchers, lead by Gregory Brown, recently reported in the Journal of Applied Physiology that the effectiveness of orally ingested androstenediol in raising serum testosterone concentrations might be limited because of liver breakdown. Brown and coworkers conducted a study where men experienced in strength training ingested 20 mg androstenediol in a sublingual tablet, or a placebo. The sublingual androstenediol tablets did cause a significant increase in these young men (average age 22.9 years old), in serum androstenedione, free testosterone, total testosterone, and estradiol concentrations. The practical benefits of the results of this study need to be determined in future studies.

As far as safety is concerned, the FDA currently permits the sale of Andro and DHEA supplements. On the practical side, as these supplements act as hormones in the body, it is reasonable to use only under doctor supervision just in case an adverse hormonal imbalance or other adverse event occurs. The medical community notes that until more studies are performed using these supplements, safety should not be assumed, and side effects (too numerous to list here) common to anabolic-androgenic steroids and estrogens, might be expected when using these testosterone precursor prohormones. Competitive athletes should note that both DHEA and Andro are banned by most sporting organizations. Concerning the issue of potency, the best way to confirm this is by requesting an independent laboratory analysis from the manufacturer.

I always advocate having people spend their money on healthy foods & sports supplements that result in naturally boosting testosterone levels and function before turning to prohormones, as well as following a healthy lifestyle. In fact, the most recent research confirms that the simple act of living a healthy lifestyle, consisting of regular exercise and good nutrition, is the best way to maximize testosterone levels. While it is well known that strength training increases testosterone levels, a recent study reported that in middle aged men, being in good health was associated with highest testosterone levels. Good health was defined as the absence of chronic illness, prescription medication, obesity, or excessive drinking of alcoholic beverages.

In addition to a healthy health food based diet, a basic sports nutrition supplement program for muscle building athletes in the pre-season and season should include a comprehensive multi-vitamin / antioxidant / mineral supplement, a high quality protein powder, glutamine, zinc methionine aspartate, branched-chain amino acids, beta-hydroxy beta-methylbutyrate, ornithine alphaketoglutrate, glucosamine, chondroitin sulfate, SAMe, ferulic acid, gamma oryzanol / beta-sitosterol, creatine monohydrate, Panax ginseng, Siberian ginseng, cordyceps, and beta-ecdysterone. Also, taking Tribulus terrestris supplements may maximize natural production of testosterone, which is thought to be the primary reason this plant increases libido and sexual performance in both males and females.