Why is maintenance of testosterone so important? Because, as explained in Chapter 5, testosterone is cortisol's "alter ego." When cortisol goes up, testosterone goes down—and vice versa. This means that keeping testosterone within normal ranges (i.e., keeping it from dropping as would be common with chronic stress such as that arising from trying to lose weight) is an important consideration in maintaining a normal stress response. In addition, testosterone is also important for controlling mood, mental function, sex drive, muscle mass, and overall metabolic rate.
Aside from helping us look (and feel) lean, fit, and strong (although these are all important), maintaining testosterone levels and muscle mass also means that we maintain energy expenditure (muscle burns the vast majority of calories), reduce risk for osteoporosis (more muscle means denser bones), and protect ourselves from other chronic diseases such as heart disease, diabetes, and syndrome X.
So what supplements are effective for keeping testosterone levels at an optimal level? In answering this question, it is important to distinguish between the maintenance of testosterone levels and muscle mass and the enhancement of testosterone levels and muscle mass. On the one hand, there are a number of dietary supplements that can maintain muscle mass during various periods of high stress, but on the other hand, there are very few (perhaps none) that can enhance muscle mass. Only high-dose anabolic steroids can do that effectively.
Numerous scientific and medical reports show quite clearly that high stress (such as extremes of exercise) and elevated cortisol levels lead to a drop in testosterone and a dramatic loss of muscle tissue. High stress causes muscles to break down as a result of a number of factors, including elevated cortisol and suppressed levels of both testosterone and its precursor, DHEA (dehydroepiandrosterone). In cases of high cortisol or low testosterone, or both, we know that reducing cortisol to normal levels and/or increasing testosterone to normal levels produces a dramatic effect on maintaining muscle mass. Importantly, however, it does not appear that reducing cortisol to below-normal levels or increasing testosterone to above-normal levels bears any beneficial effect on enhancing muscle mass (too bad for you bodybuilders out there).
The range of supplements that are commonly touted as muscle maintainers or "anticatabolics" (because they slow the catabolism, or breakdown, of muscle tissue) provide only a handful of substances that offer any good evidence of effectiveness: DHEA, eurycoma, zinc, cordyceps, conjugated linoleic acid (CLA), and HMB (hydroxymethylbutyrate). These are described below.
DHEA (dehydroepiandrosterone) is a hormone produced in the adrenal glands, the same glands that produce cortisol. In the body, DHEA is converted into other hormones such as testosterone, estrogen, progesterone, or cortisol—so too much cortisol often means not enough DHEA or testosterone. DHEA levels are known to decrease with age, particularly after the age of forty, but perhaps as early as ages twenty to thirty; therefore, dietary supplementation with DHEA is typically recommended to slow aging, improve memory, increase sex drive, alleviate depression, boost energy, promote weight loss, and build muscle mass.
DHEA supplementation, at 50–100 mg per day, has been shown to maintain normal testosterone levels (bringing them up from suboptimal levels), increase muscle mass, and improve overall feelings of well-being among a group of forty- to seventy-year-old subjects who took the supplements for six months. Another small study (involving nine elderly men) showed a link between five months of DHEA supplementation (at 50 mg per day) and improvements in markers of immune-system function (lymphocytes, natural killer cells, and immunoglobulins). It is important for us to note, however, that the studies in which DHEA is effective in enhancing muscle mass and immune function have looked at subjects with low DHEA and testosterone levels to begin with; this means the DHEA supplements were restoring them to normal levels. Studies that have looked at healthy young men, with normal DHEA and testosterone levels, have shown no muscle-maintaining or immune-enhancing benefits, and instead they have shown an increase in estrogen levels—a bad thing because of the accompanying risk for increased cancer rates.
In people with low DHEA or low testosterone levels, both of which can result from chronic stress, DHEA supplements appear to be effective at doses ranging from 50 to 100 mg per day. DHEA supplements are one of the most popular muscle-building supplements among fitness enthusiasts. Most often sold in tablet or capsule form, DHEA is also sometimes added to protein powders and other products marketed for improving muscle mass. It is also a common ingredient in commercial products focused on antiaging; its inclusion in these products is intended to counteract the well-known drop in DHEA levels that comes with age. Competitive athletes should be aware of the potential for DHEA supplementation to result in a positive drug test (for steroid use) at International Olympic Committee (IOC) and NCAA-sanctioned events.
Eurycoma longifolia, a Malaysian root often called "Malaysian ginseng" due to its energy-boosting effects, affords a natural way to bring suboptimal testosterone levels back to within normal ranges. It is also probably the best first-line therapy (before trying synthetic DHEA) for anybody suffering from chronic stress. In traditional Malaysian medicine, eurycoma is used as an antiaging remedy because of its positive effects on energy levels and mental outlook (which are most likely the result of improved testosterone levels).
Eurycoma contains a group of small peptides (short protein chains), referred to as "eurypeptides," that are known to have effects in improving energy status and sex drive. The "testosterone-boosting" effects of eurycoma appear not to have anything to do with stimulating testosterone synthesis, but rather appear to increase the release rate of "free" testosterone from its binding hormone (SHBG, sex hormone–binding globulin). In this way, eurycoma is not so much a testosterone "booster" but rather a "maintainer" of normal testosterone levels (testosterone that your body has already produced and needs to release to become active). This would make eurycoma particularly beneficial for individuals with suboptimal testosterone levels, including those who are dieting for weight loss, middle-aged individuals (because testosterone drops after age thirty), and serious athletes who may be at risk for overtraining.
The vast majority of what we know about eurycoma comes to us from rodent studies, test-tube binding evaluations, and a handful of open-label human feeding trials. In the test-tube binding studies, we find that eurycoma peptides and related compounds do indeed help to release more of the "free" form of testosterone from its binding proteins. In the rodent studies, we have more than a dozen reports of increased energy levels, improved hormonal profiles, and enhanced sex drive. In the limited number of human feeding trials, we see a clear subjective indication of reduced fatigue, heightened energy and mood, as well as a greater sense of well-being in the subjects consuming eurycoma.
Unfortunately, there are very few specific feeding studies conducted on athletes or dieters, two groups that are under severe stress and are perhaps the key customers for eurycoma-based products. There are only two U.S.-based research trials of eurycoma—one on mountain bikers, presented at the International Society of Sports Nutrition, ISSN, Annual Scientific Meeting in 2006; and one on moderately overweight dieters, presented at the North American Association for the Study of Obesity, NASSO, in 2006. These studies used 50–100 mg of eurycoma and found a maintenance of normal testosterone levels in the supplemented dieters (compared to a typical drop in testosterone among nonsupplemented dieters) and the supplemented mountain bikers (compared to a typical drop in nonsupplemented riders).
For a dieter, it would be expected for cortisol (a catabolic hormone) to rise and testosterone (an anabolic hormone) to drop following several weeks of dieting stress. This change in hormone balance (cortisol up and testosterone down) is an important cause of the familiar "plateau" that many dieters reach after six to eight weeks on a weight-loss regimen (when the weight loss stops). By maintaining normal testosterone levels, a dieter could expect to also maintain his or her muscle mass and metabolic rate (versus a drop in both subsequent to lower testosterone levels)—and thus continue to lose weight without hitting the dreaded weight-loss plateau.
For an athlete, the same rise in cortisol and drop in testosterone is an early signal of overtraining—a syndrome characterized by reduced performance, increased injury rates, suppressed immune-system activity, increased appetite, moodiness, and weight gain. Obviously, maintenance of normal testosterone levels could prevent some of these overtraining symptoms as well as help the athlete to recover faster and more effectively from daily training bouts. There are no reported side effects in animal or human studies of eurycoma. It is important to note that the majority of these studies have been conducted on hot-water extracts of eurycoma (which is the traditional Malaysian preparation). Many of the eurycoma extracts currently on the U.S. market are alcohol extracts, which provide a completely different chemical profile, one that may be less effective and less safe than the studied hot-water extracts. Typical dosage recommendations, based on traditional use and on the available scientific evidence garnered during studies of dieters and endurance athletes, call for 50–100 mg per day of a water-extracted eurycoma root (standardized to 22 percent eurypeptides).