Evidence is accumulating that the testosterone precursor androstenedione confers no benefit to men, and may even be harmful.
To assess the effect of the supplement on strength training, researchers in Tennessee randomly assigned 50 men (aged 35-65) to a twice daily dose of either placebo, 100 mg androstenedione, or 100 mg androstenediol (a secondary prohormone often found with androstenedione in supplements).
All three groups participated in intensive strength training three times a week for 12 weeks. At first, those receiving androstenedione showed an increase in free testosterone. But, by the end of the study, testosterone levels had returned to their baseline measurement.
Men taking the hormones also showed significant increases in oestradiol levels and in LDL-to-HDL ratios. In contrast, men taking placebo showed a 12.3 per cent drop in cholesterol levels.
Scientists now advise caution with this supplement, which is available without a prescription and often taken by consumers at doses far higher than those which have been studied (Arch Intern Med, 2000; 160: 3093-104).