A recent study lead by Elaine Yu, an assistant professor at Harvard Medical School, Boston, showed that hormones such as estrogen and testosterone modify cardiovascular risk factors and increase the risk of heart disease in men. These results were presented during the Endocrine Society’s 97th annual meeting, San Diego.
The study found that men have lower levels of estrogen and higher levels of testosterone when compared with pre-menopausal women. Because of this, doctors suspect that testosterone can contribute to cardiovascular disease while estrogen may protect against the condition, or that both scenarios could ultimately be true.
During the study, which enrolled 400 healthy men aged between 20 and 50, the team determined that increased levels of testosterone led to decreased levels of HDL cholesterol, known as “good” cholesterol. However, estrogen levels seemed to have no effect on HDL cholesterol, while lower levels of estrogen led to higher fasting blood glucose (sugar) levels, decreasing insulin resistance and increasing fat levels in muscles. These factors could result in the development of diabetes, a well known risk factor for the development of heart disease.
“These observations may help explain why men have a higher risk of cardiovascular disease,” noted Dr. Yu in a press release.
Dr. Yu and colleagues assessed if estrogen or testosterone controlled several cardiovascular risk factors by comparing two distinct groups of men whose hormone levels were modified temporarily with blends of medications. At the beginning of the evaluation, all male individuals received goserelin to cease their personal production of estrogen and testosterone. A total of 198 men in the first group received treatment daily for 4 months with a placebo or 1 of 4 doses of testosterone, ranging from low to high (1.25 to 10 grams). This set men’s testosterone levels from very low (as it is common before puberty) to high-normal.
A second group of 202 men had the same treatment as group 1 but also received anastrozole to block the conversion of testosterone to estrogen that, according to Dr. Yu, results in very low levels of estrogen.
Scientists concluded that neither testosterone nor estrogen are involved in the modification of LDL, or “bad,” cholesterol, in blood pressure or in body weight. “It appears that these common risk factors for cardiovascular disease are not regulated by sex hormones,” Dr. Yu said. Higher testosterone levels and lower estrogen levels in men could increase cardiovascular risk, partly explaining gender differences in heart disease.