Androstenedione is the substrate in the final biosynthetic step producing testosterone as well as certain estrogens like estrone (Fig. 1 depicts the biosynthetic steps converting androstenedione to testosterone and estrone). In theory, androstenedione consumption boosts testosterone levels because an equilibrated enzymatic system experiencing an increased substrate concentration counteracts this change by rapidly generating product and restoring equilibrium. The conversion of androstenedione to testosterone is catalyzed by the enzyme 17β-hydroxysteroid dehydrogenase (17βHSD). Enzymes, like 17βHSD, catalyze the conversion of the substrate (androstenedione) to the product (testosterone) by increasing the rate of the chemical reaction (lowering the free energy of activation or delta G++) while maintaining the reaction’s equilibrium (reduction in overall free energy or delta Gr) (Fig. 2 illustrates the reaction coordinate of androstenedione to testosterone). For example, if the consumption of 10 androstenedione molecules led to an equilibrated ratio of 9 testosterone molecules to 1 androstenedione molecule then ingesting more substrate would perturb equilibrium and generate more product. For instance, the intake of 100 molecules of androstenedione would produce 90 more molecules of testosterone at equilibrium.
Although androstenedione intake should hypothetically increase testosterone levels and lead to greater muscle mass, different studies show varying results. Some studies show ingesting androstenedione increases testosterone levels whereas other data reveal no significant influence on testosterone level at all. More importantly, no investigation has ever shown an increase in muscle size or strength. Furthermore, as previously mentioned androstenedione converts to estrone and certain studies have indicated increased estrone levels could present adverse side effects especially for men. The end result clearly suggests that androstendione doesn’t promote muscle size or strength and may be harmful to your health.
