A growing body of literature exists
regarding the effects of beta-carotene and other carotenoids on chronic diseases in humans. This article reviews and critically evaluates this literature and identifies areas for further research. This review
is restricted to studies in humans, with a major
emphasis on the most recent literature in the area of carotenoids and selected cancers. Effects of carote- noids on cardiovascular diseases, photosensitivity diseases, cataracts, and age-related macular degen- eration are also discussed briefly. Numerous obser- vational studies have found that people who ingest more carotenoids in their diets have a reduced risk
of several chronic diseases. However, intervention
trials of supplemental beta-carotene indicate that