The three-year study of healthy postmenopausal women confirms that ERT raises levels of HDL, or "good cholesterol," and reduces LDL, or "bad cholesterol." The higher a person's HDL, the lower the risk of heart disease. About 250,000 women die of heart disease each year.

-- Daily estrogen alone raised HDL cholesterol the most, enough for a 25% decrease in heart disease. But, it also created precancerous changes in the uterus.