The accumulation of abdominal fat increases with advancing age, and there is extensive evidence that abdominal obesity increases the risk for development of insulin resistance, diabetes, and atherosclerosis, according to background information in the article. Hormonal/metabolic changes that occur with aging may contribute to the increase in abdominal fat that generally occurs during middle and old age. One such change is the decline in production of the adrenal hormone dehydroepiandrosterone (DHEA). The blood level of DHEA, most of which is present in the sulfated form (DHEAS), peaks at approximately 20 years of age and declines rapidly and markedly after age 25. DHEA administration has been shown to reduce accumulation of abdominal fat and protect against insulin resistance in laboratory animals, but it was not known whether DHEA decreases abdominal obesity in humans. DHEA is widely available as a dietary supplement without a prescription.
Dennis T. Villareal, M.D., and John O. Holloszy, M.D., of Washington University School of Medicine, St. Louis, conducted a study to test the hypothesis that DHEA replacement therapy results in a decrease in abdominal fat and an improvement in insulin action in elderly persons.
The randomized, double-blind, placebo-controlled trial included 56 elderly persons (28 women and 28 men, average age, 71 [range, 65-78]) with age-related decrease in DHEA level. The study was conducted at Washington University School of Medicine from June 2001 to February 2004. Participants were randomly assigned to receive 50 mg/d of DHEA or matching placebo for 6 months.
The researchers found that DHEA replacement therapy induced significant decreases in both visceral fat (within the abdomen) and subcutaneous abdominal fat (below the skin surface) in elderly men and women. "The decrease in visceral fat relative to initial values averaged 10.2 percent in the women and 7.4 percent in the men. The DHEA therapy also resulted in a significant decrease in abdominal subcutaneous fat, averaging approximately 6 percent in both the men and women," the researchers write. The DHEA replacement also resulted in a significant improvement in insulin action that correlated with the reduction in visceral fat.
"These findings provide evidence that DHEA replacement may partially reverse the aging-related accumulation of abdominal fat in elderly people with low serum levels of DHEAS. They also raise the possibility that long-term DHEA replacement therapy might reduce the accumulation of abdominal fat and protect against development of the metabolic/insulin resistance syndrome," they write.
"Limitations of our study include the relatively small number of participants and the short duration of DHEA replacement. Therefore, our findings should be considered preliminary," the authors write. "Larger-scale and longer-term studies are needed to determine whether DHEA replacement has any adverse effects ... and will be needed to verify our findings and should include patient groups that are fully representative of the population at risk."
(JAMA. 2004; 292:2243-2248. Available post-embargo at JAMA.com)
Editor's Note: This study was supported by grants from the National Institutes of Health.