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Tuesday, February 7, 2006
Phytochemicals are substances found in plants, believed to have protective or disease preventive properties. They are non-nutritive; they do not provide calories for energy. Over one thousand phytochemicals have been described. Phytochemicals may produce their beneficial effects by different mechanisms. One mechanism is by antioxidation. Most phytochemicals are antioxidants; that is, they have the ability to combat oxidative cell damage (which can occur as a byproduct of normal metabolism and be heightened by various types of stresses). Through this activity of antioxidation, phytochemicals can potentially reduce the risk of developing certain types of cancer.
Another mechanism of action of certain phytochemicals is hormonal. For example, isoflavones, found in soy products, imitate human estrogens and may help reduce menopausal symptoms.
A third way that phytochemicals can work is by stimulating or inhibiting enzymes in the body. For example, compounds called indoles, found in cabbage and broccoli, may trigger production of enzymes that block DNA damage from carcinogens. Terpenes, found in citrus fruits, citrus peels, and cherries, may detoxify carcinogens.
A fourth way that phytochemicals can help the body is by potentially interfering with growth of tumor cells by inhibiting replication of tumor cell DNA (the genetic material found in all cells). An example is capsaicin, found in hot peppers. Capsaicin can interfere with DNA replication. It may also modulate blood clotting and can reduce the risk of fatal blood clots in the heart.
Finally, certain phytochemicals may demonstrate an antibacterial effect. Allicin, found in garlic, has antibacterial properties. Allicin is one of a group of phytochemicals called organosulfur compounds, present in garlic, chives, and onions, that may speed production of carcinogen-destroying enzymes or slow production of carcinogen-activating enzymes.
It is best to obtain these healthful substances from your diet. Since they are present in plants, having a diet rich in fruits and vegetables helps to ensure that you get your daily helping. Get at least 5 servings of fruits and vegetables every day, but strive for 9.For more information on the updated Food Guide Pyramid, please see the helpful website from the U.S. Government:
Functional foods are generally considered foods with beneficial physical or psychological effects beyond just providing calories and nutrients. However, there is no official U.S. definition for this term. Health Canada defines functional foods as those that appear similar to conventional foods, consumed as part of the usual diet, with demonstrated physiological benefits or with the ability to reduce chronic disease risks beyond basic nutrient functions. The problem is that there are many products which claim to be functional foods and make misleading or fantastic claims about what people can expect from them.For more about functional foods, see:
General cautions about supplements: Supplements are not regulated by the Food & Drug Administration the way pharmaceuticals are. Quality control can be an issue. Sometimes, a bottle of supplements may not contain the ingredients listed, in the amounts stated on the label. There can be variability in supplement content from bottle to bottle.For more on this topic see: