Your mother was right when she told you to eat your vegetables, not only because she is your mother but also because numerous scientific studies have shown that eating a variety of fruits and vegetables may have many health benefits. Fruits and vegetables contain vitamins, minerals and fiber as well as compounds called phytochemicals. Phytochemicals can aid in reducing the risk of serious diseases, including heart disease and cancer.
Scientific Background
Phytochemicals, named after the Greek word for plant phyto, are biologically active, naturally occurring chemical compounds in plant foods. The purpose of these compounds is to protect the plant against outside stressors, including
fungi, pests and bacteria. When people consume phytochemical-rich plant foods, the protective properties of these compounds are passed on. In addition, phytochemicals contribute to the color, flavor, and odor of plants. Thousands of phytochemicals have been identified in recent years and many are the subject of research to determine how these compounds help to prevent or treat disease.
Types and Function
Phytochemicals such as carotenoids, of which beta-carotene and lycopene are good examples, act as antioxidants, protecting tissues, cells and DNA against oxidative damage. Other phytochemicals with antioxidant activity include flavonoids, found in blue, blue-red, and purple fruits and vegetables. Isoflavones, which are found in soy, reduce the risk of heart disease by lowering LDL cholesterol or act as phytoestrogens, possibly preventing hormone-related tumors such as breast cancer. Indoles, found in cruciferous vegetables such as cabbage, cauliflower, broccoli and Brussels sprouts, contribute to the detoxification of carcinogens and other foreign compounds.
Expert Insight
The benefits of a diet rich in fruits and vegetables --- and thus in phytochemicals --- are so convincing that well-known health professionals such as Walter Willett, M.D., and Andrew Weil, M.D., promote a plant-based diet in their message to the general public. Willett is chairman of the Department of Nutrition at the Harvard School of Public Health and professor of medicine at Harvard Medical School. Weil is Clinical Professor of Medicine and director of the Program in Integrative Medicine at the University of Arizona. They agree that the more servings of fruits and vegetables and the greater the variety, the greater the health benefits. Each fruit or vegetable contains many different compounds that contribute to health, but no one fruit or vegetable contains everything you need.
Recommendation
The CDC, the Centers for Disease Control and Prevention, recommends that you choose a variety of fruits and vegetables to derive the greatest health benefits. It suggests choosing by color because it is an easy way to ensure that your body gets the full array of valuable compounds. As a general guideline, try to eat one serving per day of each color: red, yellow/orange, blue/purple, green, and white.
Choose Color
Common red fruits and vegetables include beets, cherries, cranberries, red grapefruit, raspberries, red apples, red bell peppers, red grapes, red onions, strawberries, tomatoes, and watermelon. Yellow and orange fruits and vegetables are apricots, butternut squash, carrots, mangoes, peaches, pineapples, pumpkin, oranges, grapefruits, mandarins, lemons, and tangerines. Blue and purple are found in blackberries, blueberries, plums, grapes. Green food includes dark, leafy vegetables such as spinach, collard greens and mustard greens, as well as artichokes, asparagus, broccoli, celery, Chinese cabbage, kiwis, leeks and lettuce. White fruits and vegetables include bananas, cauliflower, garlic, onions, turnips and parsnips.
References
- "Eat, Drink, and Be Healthy"; Walter C. Willett, M.D.; 2001
- "Eating Well for Optimum Health"; Andrew Weil, M.D.; 2000
- "Krause's Food, Nutrition, & Diet Therapy"; L. Kathleen Mahan, Sylvia Escott-Stump; 2004
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