The beta-carotene story.

Abstract

Considered to be an effective antioxidant, beta-carotene, a carotenoid that occurs naturally in many vegetables and fruits and that converts to vitamin A in the body, has been the subject of intensive cancer prevention research for decades,1; and is a commonly found supplement on the shelves of most supermarkets. This compound recently attracted significant national and international attention when results from two large-scale trials using betacarotene-the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study2; and the Beta-Carotene and Retinol Efficacy Trial (CARET)3, discussed later in this chapter—showed adverse treatment effects in terms of increased lung cancer incidence. These findings called into question the safety of supplementation with beta-carotene in high-risk individuals such as smokers and underscored the need for further research on beta-carotene, particularly to investigate possible mechanism(s)-of-action. The story of beta-carotene serves as an excellent example of the carefully designed, step-wise research strategy that must be carried out to provide clear direction for planning and implementing effective cancer-preventive public health applications. This strategy comprises a systematic review of existing epidemiologic and laboratory evidence to form cancer prevention hypotheses followed by methods development and efficacy studies to test intervention hypotheses in well-characterized populations before application to a general population and, ultimately, widespread implementation in national prevention programs.4 KeywordsNatl Cancer InstLung Cancer IncidenceWorld Cancer Research FundATBC StudyBran DietThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.