There is abundant evidence from epidemiological studies that the phytochemicals in fruits and vegetables can significantly reduce the risk of cancer, probably due to polyphenol antioxidant and anti-inflammatory effects.
Phytochemicals have been used as drugs for millennia. For example, Hippocrates in 400 BC used to prescribe willow tree leaves to abate fever. Salicin, with potent 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.
Among edible plants with health promoting phytochemicals, Diindolylmethane, from Brassica vegetables (broccoli, cauliflower, cabbage, kale, Brussels sprouts) is currently used as a treatment for Recurring Respiratory Papillomatosis tumors (caused by the Human Papilloma Virus), it 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 has potent anti-viral, anti-bacterial and anti-cancer properties through a variety of pathways and it has also been shown to synergize with Taxol in its anti-cancer properties, making it potentially a very important anti-cancer phytonutrient as taxol resistance is a major problem for cancer patients.
Some phytochemicals with potent medicinal properties may be elements, rather than complex organic molecules. Selenium for example is abundant in Brassica vegetables which may have potent anti-viral and anti-cancer properties. In a human clinical trials, selenium supplementation has been shown to reduce the HIV viral load and is currently being recommended worldwide by physicians as an adjuvant for AIDS treatments. It has also been shown to reduce mortality among prostate cancer patients. Selenium is a pre-cursor of Glutathione, a potent and important antioxidant manufactured primarily in the liver.
There are currently many other phytochemicals with potent medicinal properties that are in clinical trials for a variety of diseases. Lycopene, for example, from tomatoes is in clinical trials for cardiovascular diseases and prostate cancer. Human clinical trials have demonstrated that lycopene helps to improve blood flow through the heart and clinical studies suggest anti-cancer activity against prostate cancer. Lutein and zeaxanthin from spinach have been shown through clinical trials to directly improve human visual performance and help prevent the onset of macular degeneration and cataracts.
Many phytochemicals have anti-inflammatory properties, including Turmeric and Chia. Inflammation is a factor in many diseases of aging including Alzheimer's and Arthritis, and many artificial anti-inflammatories have unfortunate side-effects. Turmeric is also reported to be active against skin cancer (Melanoma).
In a landmark nutritional sciences study, scientists demonstrated that a diet rich in tomotoes and broccoli was more effective in inhibiting prostate cancer growth than a leading drug for prostate cancer. Nevertheless, following extensive evaluation of scientific and clinical evidence, the United States Food and Drug Administration has denied applications for health claims about the benefits of tomato consumption against prostate cancer, allowing only a limited statement on food product labels. It 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."
Clinical investigations are ongoing worldwide on thousands of 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 is believed to have contributed to the increased prevalence of the above-cited preventable or treatable causes of death in contemporary society. Interestingly though, lycopene, a phytochemical present in tomatoes, is concentrated in processed foods such as spaghetti sauce and ketchup, making those foods better sources of lycopene than fresh tomatoes.
List of foods high in phytonutrients
This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (July 2007)
Foods high in phytonutrients, or superfoods, are:
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.
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.