Phytochemicals are plant-derived chemical compounds under scientific research for their potential health-promoting properties, but with unproved benefits. "Phytonutrients" refers to plant-derived essential nutrients scientifically confirmed as important to human health.

Phytochemicals as therapeutics

There is evidence from laboratory studies that phytochemicals in fruits and vegetables may reduce the risk of cancer, possibly due to dietary fibers, polyphenol antioxidants and anti-inflammatory effects. Specific phytochemicals, such as fermentable dietary fibers, meet significant scientific agreement to be allowed limited health claims by the US Food and Drug Administration (FDA).

Phytochemicals have been used as drugs for millennia. For example, Hippocrates may have prescribed willow tree leaves to abate fever. Salicin, having anti-inflammatory and pain-relieving properties, was originally extracted from the white willow tree and later synthetically produced to become the staple over-the-counter drug called Aspirin.

An important cancer drug, Taxol (paclitaxel), is a phytochemical initially extracted and purified from the Pacific yew tree.

Among edible plants with health promoting phytochemicals, diindolylmethane, from Brassica vegetables (broccoli, cauliflower, cabbage, kale, Brussels sprouts) may be useful for recurring respiratory papillomatosis tumors (caused by the human papilloma virus), is in Phase III clinical trials for cervical dysplasia (a precancerous condition caused by the human papilloma virus) and is in clinical trials sponsored by the National Cancer Institute of the United States for a variety of cancers (breast, prostate, lung, colon, and cervical). The compound is being studied for anti-viral, anti-bacterial and anti-cancer properties through a variety of pathways and has been shown to synergize with Taxol in its anti-cancer properties, making it a possible anti-cancer phytochemical as taxol resistance is a major problem for cancer patients.

Some phytochemicals with physiological properties may be elements rather than complex organic molecules. Abundant in many fruits and vegetables, selenium, for example, is involved major metabolic pathways, including thyroid hormone metabolism and immune function. Particularly, it is an essential nutrient and cofactor for the enzymatic synthesis of glutathione, an endogenous antioxidant.

Clinical trials and health claim status

There are currently many phytochemicals possibly having medicinal properties in clinical trials for a variety of diseases. Lycopene, for example, from tomatoes has been tested in clinical trials for cardiovascular diseases and prostate cancer. These studies, however, did not attain sufficient scientific agreement to conclude an effect on any disease. The FDA position reads:

"Very limited and preliminary scientific research suggests that eating one-half to one cup of tomatoes and/or tomato sauce a week may reduce the risk of prostate cancer. The FDA concludes that there is little scientific evidence supporting this claim."

Likewise, although lutein and zeaxanthin may affect visual performance and inhibit macular degeneration and cataracts, there was insufficient scientific evidence from clinical trials for such a specific effect or health claim.

Many phytochemicals have anti-inflammatory properties in vitro, including turmeric and chia. Inflammation is a factor in many diseases of aging including Alzheimer's and arthritis. Turmeric is also reported to be active against skin cancer (melanoma).

Clinical investigations continue to assess phytochemicals with medicinal properties.

Food processing and phytochemicals

Phytochemicals in freshly harvested plant foods may be destroyed or removed by modern processing techniques, possibly including cooking. For this reason, industrially processed foods likely contain fewer phytochemicals and may thus be less beneficial than unprocessed foods. Absence or deficiency of phytochemicals in processed foods may contribute to increased risk of preventable diseases.

Interestingly, a converse example may exist in which lycopene, a phytochemical present in tomatoes, is either unchanged in content or made more concentrated by processing to juice or paste, maintaining good levels for bioavailability.

List of foods high in phytonutrients

Foods high in phytonutrients, or superfoods, are:

Other foods rich in phytonutrients or superfoods

Some animal derived foods are also considered superfoods. Beginning in 2005, there has been a rapidly growing recognition of several common and exotic fruits recognized for their nutrient richness and antioxidant qualities, with over 900 new product introductions worldwide. More than a dozen industry publications on functional foods and beverages have referred to various exotic or antioxidant species as superfruits, some of which are included in the list below.

See also



  • Page 213 of, "Nutrition for Life" by Hark & Deen published 2006 by Dorling Kindersley
  • Activation and potentiation of interferon-gamma signaling by 3,3'-diindolylmethane in MCF-7 breast cancer cells. Riby JE, Xue L, Chatterji U, Bjeldanes EL, Firestone GL, Bjeldanes LF. Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 94720-3104, USA. Molecular Pharmacology. 2006 Feb;69(2):430-9.
  • DIM stimulates IFNgamma gene expression in human breast cancer cells via the specific activation of JNK and p38 pathways. Xue L, Firestone GL, Bjeldanes LF. Department of Nutritional Sciences and Toxicology, University of California, 119 Morgan Hall, Berkeley, CA 94720-3104, USA. Oncogene. 2005 Mar 31;24(14):2343-53.
  • 3,3′-Diindolylmethane and Paclitaxel Act Synergistically to Promote Apoptosis in HER2/Neu Human Breast Cancer Cells. Journal of Surgical Research, 2006 May 15;132(2):208-13. K. McGuire, N. Ngoubilly, M. Neavyn, S. Lanza-Jacoby Department of Surgery, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
  • Pilot study: effect of 3,3'-diindolylmethane supplements on urinary hormone metabolites in postmenopausal women with a history of early-stage breast cancer. Journal of Nutrition and Cancer. 2004;50(2):161-7. Dalessandri KM, Firestone GL, Fitch MD, Bradlow HL, Bjeldanes LF Department of Molecular and Cell Biology, University of California, Berkeley, 94720-3200, USA.
  • Estrogen metabolism and risk of breast cancer: a prospective study of the 2:16alpha-hydroxyestrone ratio in premenopausal and postmenopausal women. Epidemiology. 2000 Nov;11(6):635-40. Muti P, Bradlow HL, Micheli A, Krogh V, Freudenheim JL, Schunemann HJ, Stanulla M, Yang J, Sepkovic DW, Trevisan M, Berrino F. Department of Social and Preventive Medicine, University at Buffalo, State University of New York at Buffalo, Buffalo, NY, USA, Epidemiology Division of the National Cancer Institute (Istituto Nazionale Tumori), Milan, Italy, Department of Pediatric Hematology and Oncology, Medical School of Hannover, Hannover, Germany.
  • Lycopene. Advances in Food and Nutrition Research 2006;51:99-164. Rao AV, Ray MR, Rao LG, Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
  • Tomato lycopene and its role in human health and chronic diseases. CMAJ 2000 Sep 19;163(6):739-44 Agarwal S., Rao AV., Department of Nutritional Sciences, Faculty of Medicine, University of Toronto.
  • Combinations of Tomato and Broccoli Enhance Antitumor Activity in Dunning R3327-H Prostate Adenocarcinomas. Canene-Adams K, Lindshield B, Wang S, Jeffery E, Clinton S, Erdman J., Cancer Res 2007; 67: (2). January 15, 2007
  • Selenium: from cancer prevention to DNA damage. Journal of Toxicology, 2006 October 3;227(1-2):1-14. Letavayova L., Vichova V., Brozmanova J. Laboratory of Molecular Genetic, Cancer Research Institute, Slovak Academy of Sciences, 833 91 Bratislava, Slovak Republic.
  • Low serum selenium and total carotenoids predict mortality among older women living in the community. Journal of Nutrition. 2006 Jan;136(1):172-6. Ray AL, Semba RD, Walston J., Ferrucci L, Cappola AR, Ricks MO, Xue QL, Fried LP. The Johns Hopkins Medical Institutions, Baltimore, MD, USA.
  • Suppression of human immunodeficiency virus type 1 viral load with selenium supplementation: a randomized controlled trial. Archives of Internal Medicine. 2007 Jan 22;167(2):148-54. Hurwitz BE, Klaus JR, Lllabre MM, Gonzalez A, Lawrence PJ, Maher KJ, Greenson JM, Baum MK, Shor-Posner G, Skyler JS, Schneiderman N.
  • Study of prediagnostic selenium level in toenails and the risk of advanced prostate cancer. Yoshizawa K, Willett WC, Morris SJ, et al. J Natl Cancer Inst. 1998;90(16):1219-1224.
  • Supplementation with the carotenoids lutein or zeaxanthin improves human visual performance. Ophthalmic & Physiological Optics. Kvansakul J, Rodriguez-Carmona M., Edgar DF, Barker FM, Kapcke W., Schalch W., Barbur JL. Applied Vision Research Centre, Department of Optometry and Visual Science, City University, London, UK.
  • Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. Journal of the American Medical Association.1994 Nov 9;272(18):1413-20. Seddon JM, Ajani UA, Sperduto RD, Hiller R, Blair N, Burton TC, Farber MD, Gragoudas ES, Haller J., Miller DT. Epidemiology Unit, Massachusetts Eye and Ear Infirmary, Boston 02114.

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