Dehydroepiandrosterone (DHEA) is a steroid hormone produced by the zona reticularis of the adrenal cortex. Once produced, DHEA is readily sulphated by steroid sulphatases, and this results in 99 % of DHEA being present in plasma as the sulphated form. Plasma DHEA can act as a pool of substrate to allow the synthesis of a number of anabolic steroid hormones including testosterone, androstenedione and dihydrotestosterone. In addition, DHEA can be aromatised to oestrogen. As humans age, plasma levels of DHEA fall, and this has lead to speculation that falls in the levels of DHEA may be partly responsible for the fall in testosterone levels seen, particularly in men, during ageing. Suggestions that supplemental DHEA may be able to raise levels of plasma DHEA and therefore increases testosterone levels have been made. However, despite claims from supplement companies, DHEA does not appear to be effective at improving body composition in otherwise healthy elderly men, in the absence of resistance training.
A study published in the New England Journal of Medicine in 20061, investigated the effects of DHEA supplements in elderly men with low levels of testosterone. The men received 75 mg per day of DHEA, while another group of elderly men received 5 mg per day of testosterone. A group of elderly women also received 50 mg per day of DHEA. Subjects received their treatment for 24 weeks, while control groups were administered placebos. The group of elderly men who were administered testosterone had an increase in levels of bioavailable (free) testosterone of 30.4 ng per decilitre compared to the control group. Therefore testosterone was effective at raising levels of free testosterone in elderly men. In addition, those men and women receiving DHEA had an increase in plasma levels of DHEA of 3.4 and 3.8 μg per millilitre, respectively. Therefore supplemental DHEA was effective at raising plasma levels of DHEA in both elderly men and elderly women.
However, analysis of the groups receiving DHEA showed that there was no improvements in body composition. This suggests that the DHEA was ineffective at raising plasma levels of testosterone in the subjects. This supports other research that DHEA is ineffective at raising plasma levels of testosterone in men, and only moderately effective at raising plasma levels of testosterone in women. In contrast, those men receiving the testosterone has a slight increase in fat free mass that was consistent with the low doses of testosterone administered. Supplemental DHEA does appear to be effective at improving body composition when accompanied by resistance training. One effect that was noted for the DHEA group was that they both showed evidence of increased bone mineral densities. In the men this was in the femoral neck and in the women in the ultra distal radius. Studies that have observed increases in lean mass with DHEA may therefore have been measuring bone density rather than muscle tissue.
RdB
