Dietary Androgen 'Supplements'
Separating Substance From Hype
Conrad P. Earnest, PhD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 29 - NO.5 - MAY 2021
In Brief: Recent advances in nutritional supplements have been used to aid athletic performance. Spurred by the popularity and financial success of creatine sales, athletes and supplement companies alike seek to find the next breakthrough product. Prominent among the new supplements are androgen prohormones, a class of steroid-mimicking products. Although many physicians and scientists view these supplements as potentially dangerous cousins to anabolic steroids, users see them as a means of obtaining steroid-like results with fewer adverse effects. The current literature reveals that thus far the androgen prohormone supplements tested do not enhance performance, body composition, or various parameters associated with good health.
The use of "ergogenic" aids has a rich history of folklore, theory, and applied practical science. These aids have become popular in an arena rich with charlatanism and tales woven to mythic proportion. Williams (1) estimated that approximately 89 brands of supplements exist and offer more than 300 products. Of these, 235 claim to contain unique ingredients that purportedly enhance muscle growth and/or performance. Unfortunately, the marketing of such products largely depends on emotional appeal and is often loosely based on scientific evidence. Sadly, the climate generated from such tactics is one of dashed hopes and seldom-realized dreams. Overall, these disappointments only lead to a continued feeling of distrust toward the sports nutrition supplement industry as it seeks the next blockbuster product.
An example is the marketing and sale of a class of androgenic steroids known as prohormones. These compounds either convert to testosterone directly or mimic testosterone by forming androgen-like derivatives (eg, nandrolone). While prohormone utility is questionable, an athlete's attraction to their use is understandable. The appearance of androstenedione in the United States represents a classic example of modern sporting myth, based on the hormone's rumored use by East German Olympians. Spurred by what some have called the "communist bloc steroid conspiracy," the US marketing appealed to consumers who reasoned that if the East Germans used the compounds, they must be effective. Following androstenedione's appearance in the United States, supplement companies marketed the compounds and consumers bought them, encouraged by easy product availability. Together with a chemical structure that differs only modestly from anabolic steroids, prohormones met all the qualifications for consumers who were looking for creatine's successor. Prohormones had the appeal of a "natural," steroid-mimicking, "risk-free," over-the-counter product.
To date, most sports governing bodies have banned the use of such agents. However, the agents are still abundantly available to recreational athletes: Teenage consumers are free to buy these products at many retail outlets. Although the situation lends itself to a climate full of moral, ethical, and emotional issues about supplement use, of greater importance is that both users and healthcare practitioners understand the consequences of over-the-counter androgen supplements. Despite the commercial and emotional appeal of the word "natural," all of these substances are steroid compounds that differ in chemical form and potency from their endogenous relatives. While scientists and physicians recognize the controversy surrounding these agents, the athlete-consumer is often left unaware of the potential consequences of supplement use (2,3). Unfortunately, many of these products have not been tested scientifically and include brand names that have been shortened from their International Union of Pure and Applied Chemistry (IUPAC) nomenclature. These products include: dehydroepiandrosterone (DHEA), androstenedione, 5-androstenediol, 4-androstenediol, 19-norandrostenedione, and 19-norandrostenediol.
Testosterone is the predominant male hormone and has been abused by athletes seeking to enhance body composition. Derived from cholesterol (figure 1), testosterone is produced from either the delta-4 or delta-5 pathways, in which testosterone is the major androgenic hormone regulating tissue repair, secondary sex characteristics, and various growth functions. Each pathway is under strict enzymatic regulation, and testosterone is ultimately derived from the conversion of both androstenedione and 5-androstenediol (4,5). Simply put, within a pathway, the closer a hormone's precursor is to the end product, the more pronounced the conversion to the final hormone product should be. For example, DHEA should convert to testosterone more abundantly than its precursors, and androstenedione more abundantly than DHEA because it is closer to the final product in the synthetic pathway (see figure 1). Yanaihara and colleagues (6-8) demonstrated this phenomenon in vitro in a series of elegant studies employing testicular incubations. Whether this relationship holds in vivo is not well substantiated, and studies have produced equivocal results of supplements' ability to increase testosterone concentrations (9-14).
In vitro evidence also suggests that 4-androstenediol, which lies within the delta-4 pathway, can also be converted to testosterone. In vitro results reveal that this intermediate yields more testosterone than androstenedione (15). On the basis of this one study, some supplement companies have attempted to capitalize on this particular variant claiming that the conversion is a one-way reaction that favors testosterone production. However, recent evidence (see next section) suggests otherwise because (1) this conversion occurs via a two-way reaction regulated by the enzymes 3 beta-hydroxysteroid dehydrogenase and 17 beta-hydroxysteroid dehydrogenase (15), and (2) in vivo evidence reveals a significant increase in androstenedione concentrations following 4-androstenediol ingestion (9).
The implications regarding 19-norandrostenedione/diol are even less clear (11,14,16,17). However, several major questions must be examined by healthcare professionals to determine the utility of a supplement:
DHEA is a compound in the steroid metabolic pathway that has attracted renewed attention from many athletes and scientists. Although DHEA has been promoted as an ergogenic aid for years, the evidence in young, apparently healthy athletes is wanting. Recently Brown et al (18) examined the effects of acute DHEA ingestion on serum steroid hormones and the effect of chronic DHEA intake on the adaptations to resistance training in two groups of men. In the first group, 10 young men (average age, 23 years) took a single, 50-mg dose of DHEA. Within 60 minutes after ingestion, serum androstenedione concentrations increased by 150%. Although these data demonstrate the relative ease of absorption and subsequent conversion to testosterone precursors downstream, neither serum testosterone nor estrogen concentrations were increased.
In the second part of this trial, an additional 19 men (average age, 23 years) participated in an 8-week whole-body resistance-training program and took 150 mg/day of DHEA for 8 weeks. As before, serum androstenedione concentrations increased significantly in the DHEA-treated group at 2 and 5 weeks, but serum levels of free and total testosterone, estrone, estradiol, and estriol were not affected. Blood lipid and liver transaminase concentrations were also unaffected. By the end of the experiment, men treated with either placebo or DHEA had significant and similar increases in strength and lean body mass; however, no treatment or between-group effects were otherwise noted. These and similar studies suggest that DHEA ingestion at relatively low doses (50 to 150 mg) does not enhance serum testosterone concentrations or adaptations associated with resistance training in young men (18,19).
Until recently, the best reports available on androstenedione were testimonials gathered from former East German Olympic athletes and one scientific paper examining the androstenedione supplementation in two women (12). The Eastern Bloc Olympic teams reportedly used a nasal spray to administer androstenedione (2). However, the extent of this use has not been quantified. In one of the few studies in humans, Mahesh and Greenblatt (12) compared the blood testosterone concentrations of two women following ingestion of 100 mg of androstenedione or DHEA. Androstenedione ingestion had a more pronounced effect than DHEA in elevating testosterone, suggesting that in vivo conversion patterns follow those observed in vitro. Based on this evidence, supplement companies launched marketing campaigns that cited this trial as confirmation.
Although intriguing, the commentary that women produce smaller quantities and have a lower endogenous concentration of circulating testosterone leads to an interesting postulate. That is, does a lower concentration of testosterone (such as that in women) lead to a greater percentage and/or rate of conversion from androstenedione into testosterone? Intuitively, this makes sense because biochemistry should dictate that, in part, the extent of a conversion is subject to the concentration gradient (build-up) between each hormonal conversion. This phenomenon of high concentration of endogenous testosterone, followed by low conversion rates after prohormone ingestion, appears to be true in men.
Overall, androstenedione conversion to testosterone appears to be dose-dependent. For example, several studies (10,13,20) that administered 100 mg of androstenedione per day revealed no apparent conversion to testosterone in participants, whether levels were examined as individual data or time points or as the area under the curve. However, our group (9) found a slightly higher concentration of total testosterone (nearly 23%, P<0.05) and an almost-significant increase in free testosterone (P<0.06) for the area under the curve 90 minutes after ingestion of 200 mg of androstenedione. Finally, Leder et al (20) found that a higher dose (eg, 300 mg/day) was capable of elevating testosterone concentrations by 34%. Curiously, serum estradiol concentrations rose exponentially in the Leder et al study by 42% and 128% following 7 days of supplementation in the groups receiving 100 and 300 mg/day of androstenedione, respectively.
A key point from these studies is that statistically significant elevations in testosterone concentrations at higher doses are not accompanied by any functional benefits such as increased strength, favorable changes in body mass indices, or biochemical or histologic changes in muscle tissue. In fact, studies thus far indicate that androstenedione increases a variety of estrogen subfractions (10,20), has no effect on muscle mass or strength, (10,13,19) has no effect on muscle protein synthesis or anabolism (13), and impairs lipid metabolism in apparently healthy young men (10). Furthermore, androstenedione ingestion is likely to cause individuals to test positive for steroid use because it increases urinary concentrations of androsterone, etiocholanolone, and both compounds' hydroxylated derivatives: 5 alpha and 5 beta-androstan-3, 17 beta-diols; testosterone; and epitestosterone (14). These findings are sufficient to cause the testosterone-to-epitestosterone ratio to rise above 6:1, the cutoff most sports sanctioning bodies use as a positive result in their guidelines (14). The current weight of evidence strongly suggests that androstenedione offers no positive benefits to young, apparently healthy males who ingest as much as 300 mg/day.
The metabolic pathway of 19-norandrostenedione differs from that of androstenedione (figure 2). While androstenedione is converted directly to testosterone, 19-norandrostenedione converts to nortestosterone (also known as nandrolone) in vivo (14) and does not undergo significant 5-alpha reduction to dihydrotestosterone (21). The main urinary excretion products are noretiocholanolone and norandrosterone (14), the same urinary compounds that characterize nandrolone use.
Four studies (11,14,16,17) have demonstrated that oral ingestion of 19-norandrostenedione will cause users to test positive for nandrolone. Two of these studies (11,16) are non-peer-reviewed abstracts presented at scientific meetings and do not provide any numeric data characterizing urinary metabolite concentration. One study (11) was performed by the Olympic Analytic Laboratory at the University of California at Los Angeles, and the other (16) had steroid analysis performed by Victor Uralets, PhD, of Quest Diagnostics Laboratories in San Diego. The latter analysis showed similar concentrations to those reported by others (14). Further complicating this whole issue is the observation that even trace amounts of 19-norandrostenedione may cause athletes to test positive for the prohormone.
In a recent report (17), trace amounts as low as 10 micrograms of 19-norandrostenedione caused positive test results (>2.0 ng/mL) in many subjects. As many nonandrogen supplements may be inadvertently tainted or purposely laced with undisclosed extra product, this presents cause for concern among supplement users who buy products that are supposed to be androgen-free. For fans of conspiracy theories, the former hypothesis is an attractive one given the competitive nature of companies seeking consumer dollars. Otherwise, trace contaminants are plausible if poor cleaning practices follow packaging runs in companies that sell a variety of products. The common thread in all of these studies is that 19-norandrostenedione usage, at dosages from 10 micrograms to 75 mg/day, can elevate the concentration of urinary markers for nandrolone enough to cause an athlete to test positive for the prohormone.
In contrast to oil-based, injectable steroids, oral tablets produce a markedly faster rate of metabolite appearance in the urine. Nandrolone injection produces a slow release of the compound, partly because of the oil base, and it is still detectable in the urine months later. However, when 19-norandrostenedione is taken orally, the water-solubility causes urinary metabolites to approach 100,000 ng/mL in the first postingestion void. Subsequently, norandrosterone and noretiocholanolone are detectable in the urine for 7 to 10 days following ingestion of a single 50-mg dose (14). In addition, the minor metabolites nortestosterone, norepitestosterone, estrone, and the parent norandrostenedione are detectable during the first few hours after ingestion, and the metabolites are indistinguishable from nandrolone preparations except for the first few voids.
Factors affecting 19-norandrostenedione metabolism. As previously noted, the use of universally available dietary supplements can elevate metabolite concentrations to levels that denote anabolic steroid use. Although it is not commonly believed that 19-norandrostenedione is produced endogenously, a recent experiment on athletes showed that after a prolonged, intense effort, 19-norandrostenedione concentration can increase by two- to fourfold (22). In a similar trial (23), 30 healthy men who did not use anabolic androgens undertook an intense training regimen and were asked to deliver 24-hour urine collections. As a result, researchers calculated the threshold of endogenous 19-norandrosterone concentration (2 ng/mL) to be the same as the cutoff limit advised by sports authorities for a positive test for nandrolone use. Thus, someone who is a natural prohormone overproducer, not using any oral androgens, could yield a urinary profile that mimics nandrolone (or 19-norandrostenedione) use. So significant are these findings that the Fédération Internationale de Football Association is reconsidering its policy, and the International Amateur Athletic Federation has begun its own trial to examine the same issues.
Another tactic employed by supplement companies is the promotion of lesser-known androgens with varying IUPAC nomenclature. The goal is to provide "novel" and previously "undiscovered" analogues that have not been reported in the scientific literature. Although this creates a compelling marketing campaign, it is doubtful that taking these supplements will yield equally novel effects. In an attempt to address these issues, Uralets and Gillette (24) recently examined men after the ingestion of 5-androstenedione, 5-androstenediol, DHEA, and 19-nor-5-androstenedione. The nomenclature "5" or "delta-5" designates compounds that follow a different conversion pathway to testosterone than androstenedione and other delta-4 metabolites (see figure 1). The authors found that 5-androstenedione, 5-androstenediol, and DHEA amplify most endogenous steroids, but to a lesser extent than their corresponding delta-4 analogues. Especially increased are levels of androsterone, etiocholanolone, dehydroandrosterone, DHEA, and the isomeric 5-androstenediols.
Of equal importance, however, is the finding that 5-androstenedione, 5-androstene-beta-diol, and DHEA double or triple the urinary testosterone-to-epitestosterone ratio a few hours after ingestion. Such a response is sufficient to cause a positive testosterone-to-epitestosterone test (ratio >6) for individuals with normal testosterone-to-epitestosterone ratios greater than 2. Most of these steroid levels return to normal in less than 24 hours. The exceptions to this pattern are etiocholanolone and 5-androstandiol, which remain elevated for several days. Thus, a reduced androsterone-to-etiocholanolone ratio may be an indication of delta-5 steroid abuse. The use of 19-norandrostenedione exerts a similar effect, except that all urinary metabolites are 19-nor exogenous steroids.
Although athletes are often targeted for such supplements, it is not unusual for the supplement industry to attempt to expand into other consumer markets. For supplements such as androstenedione and androstenediol, older males have been the recipients of such marketing efforts. The theory with these marketing efforts is to convince consumers that aging begins as the hypothalamic-pituitary-gonadal axis begins to decline after the age of 30 to 32, thus "requiring" supplementation. However, this form of supplementation does not appear to benefit the general aging population, either.
Broeder et al (25) showed that supplementation had no practical effect for men (35 to 65 years old) participating in resistance training for 12 weeks. After taking either 200 mg of androstenedione or androstenediol, subjects showed significant increases in androstenedione concentrations (183% and 62%, respectively). Although the androstenedione group had higher total testosterone concentrations at months 1 and 2 (P<0.05), these concentrations returned to baseline after 12 weeks. No changes were noted for the androstenediol group. In contrast, estrogen concentrations were significantly higher in the androstenedione group at all measurement periods, while only the week 12 values for the androstenediol group were statistically greater than baseline. In addition, luteinizing hormone was suppressed 33% in the androstenedione group at week 4 and remained suppressed (-18%) at week 12. These findings provide further scientific evidence that consumption of prohormone supplements can alter a patient's hypothalamic-pituitary-gonadal axis.
No significant changes were noted for sex hormone-binding globulin or free testosterone, though estrone and DHEA sulfate were elevated for both treatment groups. One interesting observation was that total testosterone and sex hormone-binding globulin were inversely correlated to leptin levels, though the clinical significance of this finding is not known. In agreement with other reports, no between-group differences were noted for muscle strength and DEXA-measured anthropometric indices of fat, bone, and muscle mass despite statistical adjustments for the initial training experience and baseline hormone concentration differences (25).
The Current Debate Status
The current consensus strongly suggests that the oral ingestion of prohormones allows them to escape digestion as evidenced by their rapid appearance in the blood and urine. Moreover, some androgen supplements given in sufficient doses do convert to more active components such as testosterone (both free and total). This effect, however, comes at a price: increases in estrogen subfractions and no positive downstream tissue effects such as increased protein synthesis, muscle mass, or strength. Thus, the athlete is left with a product that has no functional utility yet may cause the athlete to test positive for banned anabolic agents. Potentially adverse changes such as altered blood lipid and cardiovascular risk profiles also increase. Although good data suggest that steroid abuse (eg, supraphysiologic levels) is harmful for similar reasons, the questions about oral prohormone use remain unanswered. Young men's zeal for quick results makes them likely to consume more than the manufacturer's recommended daily dose, which further confounds the issue.
While prohormone use is potentially a topic for prolonged debate and speculation, use may become moot given these substances' lack of any practical effect. In short, a review of the current literature reveals that though some androgen prohormone supplements may transiently increase serum testosterone levels when taken in larger dosages, they do not enhance performance, favorably alter body composition, or positively affect various physiologic parameters associated with good health.
Dr Earnest is a program director in the division of epidemiology and clinical applications at the Cooper Institute in Dallas. Address correspondence to Conrad P. Earnest, PhD, 12330 Preston Rd, Dallas, TX 75230; e-mail to [email protected].