DALLAS -- Estrogen supplements not only improve a woman's cholesterol levels but also reduce other substances in the blood that raise the risk of a heart attack or stroke, according to a new study.
Researchers found that giving healthy women estrogen or estrogen combined with cholesterol-lowering drugs was associated with reduced inflammatory and clotting factors in the blood, said the lead author, Dr. Richard O. Cannon III.
Such factors contribute to clogging of blood vessels, said Cannon, acting chief of the National Heart, Lung and Blood Institute's cardiology branch.
"To our surprise, estrogen and estrogen combined with simvastatin reduced the inflammation and clotting potential," he said.
The findings appear in Tuesday's Circulation, a journal of the American Heart Association.
Estrogen treatment is used to treat symptoms of menopause, such as hot flashes, vaginal dryness and bone thinning. It has been shown to reduce the "bad" low-density cholesterol (LDL) and raise the "good" high-density cholesterol (HDL). But cholesterol is just one of many contributors to vessel clogging.
The researchers examined cholesterol levels, clotting factors and inflammation in blood samples from 28 women who were an average age of 57 and had relatively high levels of LDL. The women received three treatments, each for six weeks: estrogen, the cholesterol-lowering drug simvastatin and a combination of the two.
One test measured plasminogen activator inhibitor-1 (PAI-1), which blocks the body's ability to dissolve blood clots and is an indicator of blood clotting. Another test was for E-selectin, a molecule whose levels indicate inflammation.
After estrogen treatment, levels of PAI-1 were reduced by about 40 percent. With combination treatment, the levels fell 24 percent. But the levels were unchanged after simvastatin treatment.
Similar results occurred for E-selectin. With combination treatment and with estrogen treatment alone, E-selectin levels were reduced by about 20 percent. With simvastatin alone, the levels were unchanged.
Further study is needed, according to one scientist who wasn't involved in the research.
"Although the effect of estrogen on markers of inflammation and clotting in the study are encouraging, it's uncertain how these results will translate into a reduction in heart attacks and other clinical events," said Dr. JoAnn E. Manson, an endocrinologist at Harvard University and Brigham and Women's Hospital in Boston.
The only large-scale test results available are from the Heart Estrogen Replacement Study, which looked at women who had a history of cardiovascular disease, Manson said. The trials showed that women with prior cardiovascular diseases who were treated with estrogen and progestin actually showed an increase in heart attacks in the first year of treatment.
"In clinical practice, most women take a combination of estrogen and progestin. This study does not look at the combination, and progestin may attenuate some of the protective effects seen with estrogen.
"In women with high cholesterol and without a prior history of cardiovascular disease, estrogen appears to be a reasonable therapeutic option, but more research on the subject is urgently needed," Manson said.