Phytochemical

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Phytochemicals are chemical compounds that occur naturally in plants (phyto means "plant" in Greek). Some are responsible for color and other organoleptic properties, such as the deep purple of blueberries and the smell of garlic. Phytochemicals may have biological significance, for example carotenoids or flavonoids, but are not established as essential nutrients.[1][2][3] There may be as many as 4,000 different phytochemicals.[2]

Phytochemicals as candidate nutrients

Without specific knowledge of their cellular actions or mechanisms, phytochemicals have been considered possible 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 bark of the white willow tree and later synthetically produced to become the staple, over-the-counter drug aspirin.[4][5]

Specific phytochemicals, such as fermentable dietary fibers, are allowed limited health claims by the US Food and Drug Administration (FDA).[1]

Some phytochemicals with physiological properties may be elements rather than complex organic molecules. For example, selenium, which is abundant in many fruits and vegetables, is a dietary mineral involved with major metabolic pathways, including thyroid hormone metabolism and immune function.[6] Particularly, it is an essential nutrient and cofactor for the enzymatic synthesis of glutathione, an endogenous antioxidant.[7]

Clinical trials and health claim status

Phytochemical-based dietary supplements can also be purchased.[8] According to the American Cancer Society, "Available scientific evidence does not support claims that taking phytochemical supplements is as good for long-term health as consuming the fruits, vegetables, beans, and grains from which they are taken."[8]

Food processing and phytochemicals

Phytochemicals in freshly harvested plant foods may be degraded by processing techniques, including cooking.[9][10][11][12][13] The main cause of phytochemical loss from cooking is thermal decomposition.[11]

A converse exists in the case of carotenoids, such as lycopene present in tomatoes, which may remain stable or increase in content from cooking due to liberation from cellular membranes in the cooked food.[14][15] Food processing techniques like mechanical processing can also free carotenoids and other phytochemicals from the food matrix, increasing dietary intake.[11][16]

See also

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References

  1. 1.0 1.1 US FDA, Guidance for Industry: Evidence-Based Review System for the Scientific Evaluation of Health Claims
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Further reading

  • Higdon, J. An Evidence – Based Approach to Dietary Phytochemicals. 2007. Thieme. ISBN 978-1-58890-408-9.
  • Rosa, L.A. de la / Alvarez-Parrilla, E. / González-Aguilar, G.A. (eds.) Fruit and Vegetable Phytochemicals: Chemistry, Nutritional Value and Stability. 2010. Wiley-Blackwell. ISBN 978-0-8138-0320-3.
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External links

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