Symposium conclusions: biological actions of carotenoids.

The symposium on the biological action of carotenoids highlighted the antioxidant and singlet oxygen quenching properties of beta-carotene and other carotenoids of similar structure but lacking provitamin A activity. The provitamin A functions of beta-carotene were also discussed. The immuno-enhancing and anticarcinogenic actions of the carotenoids could be associated with functions unrelated to their ability to form vitamin A. Thus, the symposium emphasized the expansion of the role of beta-carotene beyond its classic nutritional function and has examined the importance of other dietary carotenoids.