Phytochemical 

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

Contents

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).1

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)citation needed, is in Phase III clinical trials for cervical dysplasia (a precancerous condition caused by the human papilloma virus)citation needed 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).citation needed The compound is being studied for anti-viral, anti-bacterial and anti-cancer properties through a variety of pathwayscitation needed 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.citation needed

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.2 Particularly, it is an essential nutrient and cofactor for the enzymatic synthesis of glutathione, an endogenous antioxidant.3

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.4 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.5

Many phytochemicals have anti-inflammatory properties in vitro, including turmeric and chia.citation needed 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).citation needed

Clinical investigations continue to assess phytochemicals with medicinal properties.citation needed

Food processing and phytochemicals

Phytochemicals in freshly harvested plant foods may be destroyed or removed by modern processing techniques, possibly including cooking.6 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.78

Interestingly, a converse example may exist in which lycopene, a phytochemical present in tomatoes, is either unchanged in content9 or made more concentrated10 by processing to juice or paste, maintaining good levels for bioavailability.

List of foods high in phytonutrients

Foods high in phytonutrients, or superfoods11, 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 worldwide12. 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

Footnotes

  1. ^ US FDA, Health Claims that Meet Significant Scientific Agreement[1]
  2. ^ Brown KM, Arthur JR. Selenium, selenoproteins and human health: a review. Public Health Nutr. 2001 Apr;4(2B):593-9.
  3. ^ Papp LV, Lu J, Holmgren A, Khanna KK. From selenium to selenoproteins: synthesis, identity, and their role in human health. Antioxid Redox Signal. 2007 Jul;9(7):775-806.
  4. ^ US FDA, Qualified Health Claims Subject to Enforcement Discretion, Docket No. 2004Q-0201
  5. ^ US FDA, Qualified Health Claims: Letter of Denial - Xangold® Lutein Esters, Lutein, or Zeaxanthin and Reduced Risk of Age-related Macular Degeneration or Cataract Formation (Docket No. 2004Q-0180)[2]
  6. ^ [3] Cooking and nutrient loss, World's Healthiest Foods
  7. ^ Liu RH. Potential synergy of phytochemicals in cancer prevention: mechanism of action. J Nutr. 2004 Dec;134(12 Suppl):3479S-3485S.
  8. ^ Rao AV, Rao LG. Carotenoids and human health. Pharmacol Res. 2007 Mar;55(3):207-16.
  9. ^ Agarwal A, Shen H, Agarwal S, Rao AV. Lycopene content of tomato products: its stability, bioavailability and in vivo antioxidant properties. J Med Food. 2001 Spring;4(1):9-15.
  10. ^ Dewanto V, Wu X, Adom KK, Liu RH. Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity. J Agric Food Chem. 2002 May 8;50(10):3010-4.
  11. ^ Pratt S, Matthews K. SuperFoods Rx (2004) HarperCollins Books, New York ISBN 0060535679 [4]
  12. ^ Starling, Shane (2006-04). "Superfruits — superheroes of functionality", Functional Foods & Nutraceuticals. Retrieved on 8 July 2007. 
  13. ^ Schauss AG, Wu X, Prior RL, Ou B, Huang D, Owens J, Agarwal A, Jensen GS, Hart AN, Shanbrom E. Antioxidant capacity and other bioactivities of the freeze-dried Amazonian palm berry, Euterpe oleraceae mart. (acai). J Agric Food Chem. 2006 Nov 1;54(22):8604-10.Abstract.

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