Twenty years ago, high doses of beta carotene were thought to have cancer-preventing power, and two large clinical trials were launched to determine if it might reduce lung cancer among cigarette smokers.But the disease-fighting properties of beta carotene, a carotenoid which the body converts into vitamin A, fell far short, the studies found. One trial was even halted before its scheduled end because of the adverse effects of high doses of beta carotene supplement: it appeared to raise the risk of lung cancer, as well as death from heart disease and other causes.Now, it appears that some of the adverse effects of high beta carotene doses can persist for women in particular, according to a study in the Dec. 1 issue of the Journal of the National Cancer Institute.
