Abdominal fat accumulates with age and is associated with a higher risk of diabetes and atherosclerosis. One reason for abdominal fat deposition may be a decline in dehydroepiandrosterone (DHEA). In animal studies, DHEA administration has been shown to decrease abdominal obesity and protect against insulin resistance. It is possible that DHEA, a readily available dietary supplement, has a similar effect on humans. Villareal and Holloszy investigated the effects of DHEA supplementation on abdominal fat and insulin resistance in humans.
This randomized, double-blind, placebo-controlled trial enrolled 56 volunteers who were 65 to 78 years of age. Abdominal fat was measured in these patients using proton magnetic resonance imaging. Insulin sensitivity was calculated on the basis of glucose tolerance tests. Serum DHEA, lipid, and prostate-specific antigen levels were measured, and a diary of diet and physical activity was obtained at the beginning and end of the study.
Of the enrolled patients, 52 remained in the study long enough for follow-up evaluations. At the end of six months, the DHEA replacement group had a statistically significant decrease in body weight (0.9 kg [2 lb]) compared with the placebo group. DHEA replacement therapy increased serum levels to the young normal range. The relative reduction in visceral fat was 10.2 percent in women and 7.4 percent in men, with a concomitant reduction in subcutaneous abdominal fat. The DHEA group also had lower insulin levels at the six-month glucose tolerance test, with similar glucose levels, indicating increased insulin sensitivity. No adverse events related to DHEA replacement were noted, nor were there significant changes in prostate-specific antigen levels.
The authors conclude that DHEA replacement appears to reduce visceral and subcutaneous abdominal fat and improve insulin action in this small group of older patients. One difference between this study and previous small studies with negative findings was its higher serum DHEA levels. Long-term effects of DHEA are not known, particularly the consequences of higher insulin growth factor 1 and estradiol levels in men and women and higher testosterone levels produced in women.