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United States Department of Agriculture

Agricultural Research Service

Food: A Powerhouse of Protection
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By Huawei Zeng

 The right food choices can provide a rich source of various essential healthful chemicals.  It is through food that we get our micronutrients, such as vitamins and minerals, and macronutrients, such as carbohydrates, fiber, protein, and essential fat.   Thus, foods that contain healthful bioactive components are essential for energy supply, body development, and maintenance. In addition, certain foods, or what some call functional foods, have specific health benefits, The Institute of Food Technologists defines functional foods as foods and food components that provide a health benefit beyond basic nutrition for an intended population. 

 Fortified, enriched or enhanced foods, and dietary supplements, often provide essential nutrients beyond the quantities necessary for normal health maintenance, growth and development.  Plant foods on the other hand, contain biologically active components beyond those defined as essential nutrients--such as thousands of antioxidative phytochemicals--that impart health benefits and desirable physiological effects.  It's no surprise that some prescription drugs in America originated as plant products.

 The U.S. Food and Drug Administration allows food labels to state that diets low in fat and high in fruits and vegetables ``may'' or ``might'' reduce the risk of some cancers.  Cancer, ranked as a leading cause of death in the United States, is a constellation of more than 100 different diseases.  Each is characterized by the uncontrolled growth and spread of abnormal cells. 

 Cancer has many causes and stages in its development.  Degrees of risk, in addition to dietary factors, include a family history of a specific type of cancer, cigarette smoking, alcohol consumption, overweight and obesity, ultraviolet or ionizing radiation, and exposure to cancer-causing chemicals.

 Although scientists are still in the process of understanding these causes, there exists a large and growing body of evidence showing that the foods we choose each day play a critical role in disease prevention. Plant foods, again, contain "extra" bioactive substances that, while not on the government's list of essential nutrients, may still be protective against cancer risk.

 These disease-fighting nutrients can boost our antioxidant activity, immune systems, elimination of toxic substance, and inhibition of tumor cells and carcinogenic fat.

 Scientists have studied many protective aspects of a variety of plant foods.  Some are explained below:

  • Beans, also known as legumes, include lentils, peas and many other bean varieties. Saponins, protease inhibitors and phytic acid are the key active ingredients in beans that appear to have a role in cancer prevention. Beans are also rich in fiber, and diets high in fiber are also linked to lower cancer risk.
  • Berries are known as good sources of vitamin C and fiber and diets high in both of these substances have been consistently linked to lower cancer risk.
  • Dark green leafy vegetables include spinach, kale, romaine lettuce, leaf lettuce, mustard greens, collard greens, chicory and Swiss chard are excellent sources of fiber, folate and a wide range of carotenoids which seem to help prevent cancer by acting as antioxidant.
  • Green tea contains numerous active ingredients, including polyphenols and flavonoids, which are potent antioxidant.
  • Tomatoes, the red or pink color of several fruits tomatoes, watermelon, papaya, pink guava and pink grapefruit comes chiefly from a carotenoid called lycopene. This potent antioxidant, together with a group of related compounds collectively called "red family," has displayed anti-cancer potential.
  • Wholegrain means that all three parts of the grain kernel (germ, bran and endosperm) are included. Other whole-grain foods include brown rice, wheat breads, rolls, pasta, cereals; whole grain oat cereals such as oatmeal, popcorn, wild rice, tortilla and tortilla chips, corn, kasha (roasted buckwheat) and tabouleh (bulgur wheat).

In general, a wide variety of vegetables and fruits offers a wide variety of phytochemicals. Each food item offers its own profile of these protective substances. Evidence is mounting that the mineral, vitamins and phytochemicals in many plant foods are likely to interact, and have synergistic effect on cancer protection. For example, the anticancer activity of cranberry and apple together is much higher than the separate measurements for these fruits. So you may include as many different ones as possible each day for a powerhouse of protection. It is recommended that at least 2/3 of your plate should be filled with vegetables, fruit, whole grains and beans. 

Last Modified: 2/9/2007
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