on the epidemiologic level , studies of the last few years indicate the need to investigate further the potential role of fats as related to all the major sites of cancer , to distinguish the effects of various fractions of fiber as well as of fibers deriving from fruits , vegetables and grains , and to examine more closely carotenoids as opposed to retinoids to explore further the proposition that although carotenoids may reduce risk for a number of cancers , retinoids may play no part .
C0007271
carotenoids
C0035339
retinoids