Beta-carotene was tested as a potential cancer preventive in two large NCI-funded randomized trials in persons at high risk of developing lung cancer. Contrary to expectations, the incidence of lung cancer increased among the former and current smokers who took beta-carotene. The magnitude of increased risk in these trials represented approximately six cancers per 1000 participants in the intervention groups, compared with five cancers per 1000 participants in the control groups, a difference too small to be apparent in any observational epidemiologic study, wrote Peter Greenwald, director of the NCI Division of Cancer Prevention, in the Jan. 1, 2003, issue of the Journal of the National Cancer Institute. If the randomized, controlled trials had not been carried out, specific dietary guidelines based on epidemiologic evidence might have been considered, an action that would likely have caused harm to public health, Greenwald wrote. The beta-carotene story thus demonstrates clearly that although epidemiologic evidence can provide a basis for developing hypotheses of benefits of food constituents, these hypotheses must then be tested in randomized, largescale clinical trials. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.