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Androstenedione (Andro)


Androstenedione Facts

Androstenedione (popularly known as Andro) is a natural hormone proven to increase testosterone levels. It is a natural substance found in humans, animals and in the pollen from many plants. It is produced in the gonads and adrenal glands of all mammals. As a metabolite of DHEA, it serves as a direct precursor in the bio-synthesis of testosterone. The oral form of Androstenedione is metabolized, by a single liver enzyme, into testosterone.


Androstenedione is currently used as a nutritional supplement to grow bigger muscles and stronger bones. This implies that androstenedione may have anabolic properties. Even though it has not been convincingly demonstrated yet that androstenedione is an anabolic steroid, its anabolic properties are likely based on its proven ability to increase testosterone levels. The role of testosterone in building stronger muscles and bones is widely accepted. Thus, high doses of testosterone-boosting drugs combined with strength training have been shown to increase muscle size and strength even in normal young men. This confirms what thousands of athletes who take anabolic steroids have known for decades. Yet androstenedione is different from testosterone-boosting drugs in a number of important aspects. To begin with, androstenedione is a naturally occurring substance that is produced by the body itself. In contrast to synthetic anabolic steroids, androstenedione is right at home in the human body, and perfectly complements the complex hormonal network in the body.

Even though much of the publicity on the use of androstenedione is toward body builders and athletes, it is important to note that people over the age of 40 years claim great benefits by boosting the amounts of testosterone in the body. The beneficial effect claims include enhanced libido, protection against age-related diseases, such as heart and prostate disease, osteoporosis and muscle atrophy. Androstenedione have also claimed to be effective in improving mood and energy levels.


Androstenedione, a popular supplement taken to enhance athletic performance, did not enhance muscle-building or increase testosterone in the blood but appeared to produce adverse health effects in a small study of young men, according to an article in a recent issue of The Journal of the American Medical Association (JAMA).

Douglas S. King, Ph.D., of Iowa State University in Ames, and colleagues studied 30 healthy men ages 19-29 with normal testosterone levels in a randomized controlled trial.

Twenty of the men performed eight weeks of whole-body resistance training. During weeks one, two, four, five, seven and eight, 10 of the men were given 300 mg of androstenedione a day, and the others were given a placebo.

The researchers discovered that muscle strength did not differ between the placebo and androstenedione groups before training or after four and eight weeks of resistance training and supplementation. They also found that testosterone levels in the blood were not affected by the supplement intake.

The researchers did find a significant lowering of high density lipoprotein (HDL, or “good”) cholesterol in the blood in those receiving androstenedione. Also, certain estrogen levels in the blood increased in the men taking the supplement. In men, increased blood estrogen levels are associated with the development of gynecomastia (enlarged breasts), and increased risk of cardiovascular disease and pancreatic cancer.

In an accompanying editorial, Charles E. Yesalis III, MPH, Sc.D., of Pennsylvania State University in University Park, writes: “During the past year, the public was exposed to a barrage of drug scandals in sports. These involved Olympic champions in track and field, swimming and snowboarding, as well as elite cyclists, a three-time winner of the Boston Marathon, and a professional tennis player.

However, of all the drug-related stories in 1998, none received more media attention than home run record holder Mark McGwire's admission that he used androstenedione as a performance-enhancing substance.

“When questioned, supporters of McGwire borrowed several pages from today's political playbook and argued that what McGwire did was not illegal, was a personal matter, and, besides, the quest for the home run record was good for baseball,” Yesalis continues. “Nevertheless, while androstenedione is not outlawed in major league baseball, it is on the banned drug lists of the International Olympic Committee, the National Football League and the National Collegiate Athletic Association. Many expressed concern that the use of this agent by sports heroes, who may be considered role models, might encourage youngsters to use this steroid hormone. This apprehension is supported, in part, by the claim by Barry McCaffrey, director of the Office of National Drug Control Policy, that androstenedione use by youngsters has increased five-fold since McGwire's admission.

Yesalis writes that the authors of this new research have conducted a well-designed study that has provided valuable information, but that several scientific questions remain and indicate the need for further investigation.

“For example, of the young men enrolled, only two had ever engaged in resistance training, and that training had been more than one year earlier. Such inexperienced weight trainers generally make significant gains in the early phase of resistance training programs. These large strength gains could overshadow, statistically, any potential gains from androstenedione.”

He adds: “Future studies may need to focus on the effects of a higher dose of androstenedione administered during a period longer than eight weeks. While the study by King used a daily dose of 300 mg, recent advertisements for androstenedione recommend a daily dose of 500 to 1200 mg.”

Yesalis concludes: “In the case of androstenedione, the study by King contributes to the evidence suggesting that the government should carefully consider intervening and remove androstenedione and its derivatives from the market.”

Known Negative Effects

Information about possible side effects and risks of androstenedione is very limited. Also, recent studies show that the drug's actions don't support manufacturer's claims. While a few individuals have shown increased levels of testosterone, most failed to achieve increases in blood testosterone levels. Initial medical research has raised concerns about this supplement's safety. Doctors worry that androstenedione may increase the risk of heart disease or liver cancer. In addition, research also associates androstenedione use with increases in estradiol, a female estrogen.

Athletes should consider the effect rapid testosterone increases have on their personality. Androstenedione will not convert to estrogen (DHEA does) so there are no negative estrogenic side effects possible. Androgens are the male sex steroids. They increase body hair, facial hair and acne; deepen the voice; enhance prostate growth; and promote muscle growth. The best known androgen is testosterone. Too much androgen shuts off the body's own production of testosterone. This can impair normal testicular function - "it shrinks your grapes to raisins." The use of androgens is especially dangerous among adolescents in whom it is known to stunt growth.


While it is almost impossible to take androstenedione without any side effects, 100 mg per day seems to be the optimum dosage. Adolescents should not take it at all because the boost in hormones are very harmful, and they normally have a higher level of testosterone on a daily basis. It would be a waste of money for any one under 25 to take androstenedione, or any prohormones for that matter. Most athletes take between 50 mg. and 300 mg. daily, depending upon the desired level of gains and the time spent in the gym.


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