DHEA and androstenedione are prohormone molecules. When the body makes sex hormones such as testosterone and estrogens, they are actually constructed during several chemical reactions beginning with cholesterol. In the gonads (ovaries for females and testes for males) cholesterol can be completely converted to testosterone and estrogens and released into the blood. Two molecules along the way to the sex hormones are DHEA (dehydroepiandrosterone) and androstenedione, with the former coming just prior to the latter (Figure 11.3). Androstenedione is just one chemical reaction shy of testosterone which is one of the most significant factors that evokes muscle protein production and promotes growth.
In order for androstenedione and DHEA to raise testosterone levels they must be absorbed from the digestive tract, circulate, and be converted to testosterone by enzymes in organs such as the liver and testes. Interestingly, skeletal muscle lacks the enzymes needed to convert DHEA and androstenedione to testosterone. It should also be mentioned that both androstenedione and DHEA can be converted to estrogen molecules as well. To counter this, some supplement manufacturers recommend taking substances such as diadzein or chysin (flavonoids) in an attempt to block this undesirable conversion.
In general, researchers have failed to show that androstenedione and DHEA supplements do indeed increase testosterone levels in the blood when dosages mimicked manufacturer recommendations (100 milligrams of androstenedione and 25 to 50 milligrams of DHEA). However, in a research study, when three times the recommended dosage for andro-stenedione was tested, testosterone levels did increase by 24 percent but estrogen levels also increased by 128 percent. Furthermore, another research study revealed that when men with more body fat were provided androstenedione supplements they were more efficient in converting androstenedione to estrogen than leaner men. This makes sense, as adipose tissue contains the enzymes necessary to convert androstenedione to estrogens.
Both DHEA and androstenedione can be used by our body to make testosterone (and estrogen) and use is banned in some sports.
Androstenedione and DHEA are considered nutrition supplements as they are naturally found in foods such as meats (muscle and organ). Recently the FDA demanded that supplement companies stop selling supplements with androstenedione because of health risks. It should be mentioned that both of these substances are among the list of so-called sport doping agents banned by the International Olympic Committee, National Football League, and the National Collegiate Athletic Association.
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