Effect of Androstenedione Ingestion on Plasma Testos- terone in Young Women; a Dietary Supplement with

Androstenedione is readily available as a “dietary supple-ment ” and can be sold without restriction in most coun-tries, including the US and UK. Manufacturers market androstenedione as a “prohormone ” that can increase blood testosterone concentration, thereby increasing lean body mass and strength. It is available in capsules pur-ported to contain 50, 100, or 300 mg of the steroid, and the manufacturers suggest that the “desired ” effects can be gained by taking 100–300 mg/day orally. However, a single dose of 100 mg/day is insufficient to increase serum testosterone concentrations in men (1–4). Even with higher “recommended ” doses of either 200 or 300 mg/day (given as either single or multiple administra-tions), no significant increase has been observed in most studies (1, 3, 5), albeit in one investigation, 4 of 14 me