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.
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
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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
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