What Is the Scientific Evidence for Beta-Carotene?
Cancer Prevention The story of beta-carotene and cancer prevention is full of apparent contradictions. It starts in the early 1980s, when the cumulative results of many studies suggested that people who eat a lot of fruits and vegetables are significantly less likely to get cancer. 40,41 A close look at the data pointed to carotenoids as the active ingredients in fruits and vegetables. It appeared that a high intake of dietary carotene might significantly reduce the risk of lung cancer, 42 bladder cancer, 43 breast cancer, 44 esophageal cancer, 45 and stomach cancer. 46However, observational studies cannot prove cause and effect. It is always possible that individuals who consume a great deal of carotenoids in the diet are different in other ways; for example, they might exercise more or have healthier lifestyles in other regards. This is not a purely theoretical issue. For example, based primarily on observational studies, hormone replacement therapy was promoted as a heart-protective
