If you follow the news about health research, you risk whiplash. First garlic lowers bad cholesterol, then—after more study—it doesn’t. Hormone replacement reduces the risk of heart disease in postmenopausal women, until a huge study finds that it doesn’t (and that it raises the risk of breast cancer to boot). Eating a big breakfast cuts your total daily calories, or not—as a study released last week finds. Yet even if biomedical research can be a fickle guide, we rely on it.