Susan Eileen Painter

For over a decade, the single most widely prescribed drug for women in America was made from horse estrogens. It was called Premarin. "Horse estrogens are nothing like human estrogens," says Dr. William Davis, a cardiologist of 25 years and author of the bestsellers Wheat Belly and Super Gut. Doctors handed it out on the strength of weak observational data suggesting it lowered breast cancer, uterine cancer, and heart disease. Then the real randomized trials, the Women's Health Initiative and the HERS trial, were run. The opposite was found. "Horse estrogen increased breast cancer risk, increased uterine cancer, increased cardiovascular death, and accelerated dementia," Dr. Davis said. "So for 10 years, ladies were given this drug that caused disease." His point is blunt. Humans deserve human hormones. "I wouldn't give you zebra testosterone," he said. Yet for a decade, women were handed the horse version.