For centuries people consumed food simply for its nutritional value. But in recent decades, the role of specific foods is evolving into one of prevention. This trend is based on research findings such as a lower incidence of cancer among people who ate more fruits and vegetables, and less heart disease in those whose diets contained less fat.
Nutrition experts believe that the functional components of food that may reduce the risk of cancer include traditional nutrients such as folic acid, vitamins A and C, fiber, and selenium, as well as recently discovered compounds such as phytochemicals and other naturally occurring elements in both plant and animal foods. Some components, such as lycopene in tomatoes, have antioxidant properties, which protect cells against damage from oxidation. Others, such as soy, have hormone-like actions, which help to protect against hormone-dependent cancers such as endometrial and ovarian cancer.
In the latest findings, scientists have discovered that some compounds in food can encourage the body to produce protective enzymes. These enzymes help to detoxify cancer-causing substances and prevent cell damage that can lead to cancer. Other compounds in foods may help to delay or inhibit the advancement of cells to the clinical stage of cancer.
While this research looks promising, experts caution that much remains unknown.
Following is a list developed by the International Food Information Council of some functional compounds and their potential roles in reducing the risk of cancer. (Research on these foods continues, and some of the possible roles identified here are the subject of controversy.)
| Food |
Functional
Component* |
Possible Role(s)in
Reducing Cancer Risk |
| Broccoli, broccoli sprouts |
Sulphoraphane |
Stimulates the body to produce its own protective enzymes, neutralizes free radicals |
| Tomatoes and tomato products |
Lycopene |
Potent antioxidant; may reduce risk of prostate cancer |
| Garlic, onions |
Allyl sulfides |
Boosts levels of naturally occurring enzymes that may help maintain a healthy immune system |
| Soybeans |
Isoflavones |
May reduce the risk of estrogen-dependent cancers by blocking receptors for estrogen; may inhibit the formation of blood vessels that assist tumor growth |
| Grapes, strawberries, raspberries |
Ellagic acid |
May block the production of enzymes needed for cancer cells to reproduce |
| Oranges, lemons |
Limonene |
Boosts levels of naturally occurring enzymes that may break down carcinogens |
| Green tea |
Polyphenols |
May neutralize free radicals to help block damage to DNA |
| Beef, dairy products |
Conjugated linoleic acid |
May decrease risk of certain cancers |
| Dairy products |
Calcium, sphingomyelin |
May inhibit tumor cell growth and aid in cell death |
| Flaxseed |
Lignans |
Acts as a phytoestrogen; similar to soy |
| Whole wheat |
Phytic acid |
May suppress the oxidative reactions in the colon that produce damaging free radicals |
*These represent one example of functional components; most functional foods contain many active components with potential health benefits.
Much of the research on functional foods is in preliminary stages, so it is too early to make firm promises. However, the country's leading nutritional experts believe there is potential for our food choices to help protect us against a variety of diseases.
Source: International Food Information Council Foundation. Functional foods: can they reduce your risk of cancer? Food Insight, May/June 2001, p.2-3.
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