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Garlic & Onions
Tuesday, March 27, 2007
Phytochemicals are healthy substances in fruits and vegetables that help the body fight disease. Such phytochemicals can be found in blueberries, tomatoes, broccoli, and red grapes, as well as many other fruits and vegetables.
Garlic and onions are in the same family of foods. They are part of the allium family of vegetables, along with leeks and chives. Both have cancer-fighting substances.
Previous studies with cancer cells have shown that compounds in garlic and onion can inhibit tumor growth. A recent Italian study published in the American Journal of Clinical Nutrition analyzed dietary data of almost 10,000 cancer patients and 15,000 healthy control subjects. The researchers found that more frequent onion and garlic intake was associated with reduction in the risk of many types of cancer, including tumors of the colon, esophagus, voicebox, and throat. Those consuming the most garlic showed a 25-88% drop in cancer risk, depending upon the type of cancer. Those consuming the highest amount of onions per week had a risk reduction of 10-57%.References:
- Galeone C, Pelucchi C, Levi F, et al. Onion and garlic use and human cancer. Am J Clin Nutr 2006;84:1027-32.
- Izzo AA,Capasso R, Capasso F. Eating garlic and onion: a matter of life or death. Br J Cancer 2004;91:194.
- Buiatti E, Palli D, Decarli A, et al. A case-control study of gastric cancer and diet in Italy. Int J Cancer 1989;44:611-6.
- Shirin H, Pinto JT, Kawabata Y, et al. Antiproliferative effects of S-allylmercaptocysteine on colon cancer cells when tested alone or in combination with sulindac sulfide. Cancer Res 2001;61:725-31.
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: