Effects of anthocyanins and anthocyanin-rich extracts on the risk for cancers of the gastrointestinal tract.

Anthocyanins are the largest group of water-soluble pigments in the plant kingdom. Anthocyanins are responsible for most of the red, blue, and purple colors of fruits, vegetables, flowers, and other plant tissues or products. In recent years, numerous studies have shown that anthocyanins display a wide range of biological activities. This review summarises recent literature evidence on the association of anthocyanins and anthocyanin-rich extracts consumption with the risk for gastrointestinal tract cancer, concentrating on the results from in vivo animal model tumor systems, as well as data from human epidemiological studies. Potential cancer chemopreventive activities of anthocyanins were revealed from in vitro studies. In vivo animal model tumor systems showed that dietary anthocyanins inhibit cancers of the gastrointestinal tract. Some epidemiological studies have revealed protective effects of anthocyanins consumption on gastrointestinal cancer risk in humans. Pharmacokinetic data indicate that absorption of anthocyanins into the bloodstream of rodents and humans is minimal, suggesting that they may have little efficacy in tissues other than the gastrointestinal tract and skin. Future studies should be undertaken to determine if the anticancer effects of anthocyanins are due to the parent compounds and/or to their metabolites.