The consumption of fruits and vegetables is inversely related to the risk of colorectal cancer and colorectal adenomas, the precursor lesions of this disease. Individuals who regularly consume fruits and vegetables in adequate amounts have a 2-fold reduction in adenoma and colon cancer risk. Fruits and vegetables contain a number of constituents associated with colorectal cancer prevention, such as antioxidant vitamins and numerous micronutrients, including the plant phenolics. Fruits and vegetables also contain dietary fiber.

A number of studies support a role for plant phenolics in colorectal cancer prevention. Plant phenolics are divided into three categories based on their chemical structure: the simple phenols and phenolic acids, hydroxycinnamic acid derivatives, and flavonoids. These agents inhibit carcinogenesis in the initiation, promotion, and progression stages.

Flavonoids constitute the most important single group of dietary phenolics and include catechins, proanthocyanins, anthocyanidins, flavones, and flavonols and their glycosides. These compounds are abundant in plant foods, and a typical fruit serving of 200 g contains 50–500 mg of mixed flavonoids.

Catechins are a class of flavonoids with potent antioxidant and cancer chemopreventive properties. Catechins are naturally occurring and minimally toxic compounds that can be added to a growing list of agents that suppress intestinal tumor formation (including colon cancer). Because of its wide bioavailability, this agent may prove effective against a variety of human epithelial tumors. Catechins may prevent cancer initiation and, at later stage of developement, spreading. Recent work showed that dietary supplementation with a 1% grape seed extract reduced tumor formation in mice by 44% due to the high catechin content of the grape seed extract.

Plants Rich in Catechins

  • Tea leaves, black, dry - 137 mg
  • cacao beans - 88 mg
  • grape seeds, raw - 74 mg
  • Dark chocolate - 64 mg
  • Tea leaves, green - 57 mg
  • Carob flour - 50 mg
  • Blueberries, raw - 37 mg
  • Blackberries, raw - 37 mg
  • Plums, black - 17 mg
  • Grpaes, black - 10 mg


  1. (+)-Catechin Inhibits Intestinal Tumor Formation and Suppresses Focal Adhesion Kinase Activation in the Min/+ Mouse1 Michael J. Weyant, Adelaide M. Carothers, Andrew J. Dannenberg and Monica M. Bertagnolli. Cancer Research 61, 118-125, January 1, 2001