STAY HEALTHY EAT FRUIT AND VEGETABLES

there is more to eating fruits and vegetables than getting your daily quota of vitamins and minerals.

“I’m feeling pretty good about my exercise program now I need to do something about my diet. I eat the same thing day after day: cereal for breakfast, a sandwich for lunch and something quick and easy for dinner. I was comparing my diet to the food pyramid the other day. My worst area is fruits and vegetables, especially vegetables. Most days I eat only one or two vegetables, sometimes none. Do you know any really easy ways to get more vegetables into my diet? And do you think I really need three to five servings of vegetables a day if I take vitamins?”

Why fruits and vegetables?

Most people know that fruits and vegetables provide many important vitamins and minerals. If vitamins and minerals were the only reason to eat plenty of fruits and vegetables, then supplements might be a fair substitute. But fruits, vegetables and other plant foods such as legumes (soy beans, lentils, split peas, etc.), grains, nuts and seeds also contain various types of dietary fiber, a variety that provides many health benefits and is difficult to obtain from supplements alone. In recent years, scientists have also found that plant foods contain an array of other components that appear to promote health and prevent disease. These components, known as “phytochemicals,” literally plant chemicals, have been associated with reducing risk for disorders such as macular degeneration (a leading cause of blindness), several types of cancer and artery disease.

Nutrients vs. phytochemicals

Vitamins and minerals are classes of nutrients. A nutrient is a substance obtained primarily from the diet (the exception is vitamin D, which people can manufacture given enough sunlight) that is essential for good health; when a person’s diet lacks nutrients, a deficiency disorder develops. Without vitamin C, for example, people develop scurvy. Without iron, they become anemic. Many deficiency diseases are eventually fatal if no intervention occurs.
Unlike nutrients, phytochemicals are not necessary for normal physical health. Many seem to possess disease-fighting properties, but people will not develop deficiency symptoms if these chemicals are absent from the diet. The distinction between nutrients and phytochemicals is not really black and white, however. Many nutrients act as phytochemicals; that is, they have disease-preventing actions in addition to their actions as nutrients. Vitamin C, for example, helps to prevent cellular damage caused by substances called “free radicals” in addition to its role in maintaining healthy connective tissue. Folic acid, a B vitamin, is essential for the formation of healthy red blood cells, but epidemiological evidence now suggests that people with higher folic acid levels have a lower risk of colon cancer.

How do phytochemicals work?

Phytochemicals work in many different ways. Some, such as the “phytoestrogens” found in soy beans and their products, interact with hormone receptors, either triggering or inhibiting those receptors and their actions. Phytoestrogens, for example, seem to mimic estrogen’s cholesterol-lowering activity while blocking its carcinogenic effect on breast tissue.

Some phytochemicals appear to detoxify or block the action of potential carcinogens, such as free radicals, mentioned above. This helps to prevent precancerous changes in the cell and its genetic material. Other phytochemicals seem to help suppress malignant changes that have already occurred in cells. Cellular damage is associated with artery disease, cancer and other disorders that occur as part of the aging process.

Food sources of phytochemicals

There are dozens of helpful phytochemicals. Since they are found in many different types of plant foods, it is important to include a variety of foods in one’s diet. Variety is also important because the research on beneficial phytochemicals is still preliminary; many more may be discovered in the future. Some experts recommend that in addition to consuming five to nine servings of fruits and vegetables a day, people should eat at least three different colors of fruits and vegetables every day to ensure variety. Especially helpful foods include the following:

Cruciferous vegetables: Many studies have suggested that a high intake of cruciferous vegetables helps to prevent cancer. Broccoli, cabbage, brussel sprouts, kale, cauliflower and turnips are found in this group.

Citrus fruits and juices: These contain terpenes, which have been shown to fight cancer in laboratory animals.

Red, orange and yellow fruits and vegetables: The red and yellow plant pigments known as carotenoids live here, as well as in many dark green vegetables such as broccoli and spinach, where they are masked by the chlorophyll. Beta carotine is the most famous, or perhaps infamous, of the hundreds of chemicals in the carotenoid family — infamous because treatment with beta carotene supplements has been associated with an increased risk of lung cancer in smokers. Despite this association, a positive association with a high intake of carotenoids from foods and lower risk of cancer persists in many studies. Therefore, while beta carotene supplements may be harmful, consuming a wide variety of carotenoid food sources promotes good health. This variety can be found in red, orange and yellow fruits and vegetables, including carrots, sweet peppers, winter squashes, pumpkin, cantaloupe and strawberries. Lycopene, found in tomatoes and tomato products, has been associated with reduced risk of prostate cancer.

Dark green leafy vegetables: The carotenoids lutein and zeaxanthin, found in dark green leafy vegetables such as spinach and kale, have been associated with protection from macular degeneration.

Garlic and onions: Garlic and onions are members of the allium family, along with chives, leeks and scallions. These foods supply helpful sulfer compounds that help reduce the production of cholesterol by the liver. These vegetables are also associated with reduced risk of colon cancer.

Other common fruits and vegetables: Many common fruit and vegetable snacks not mentioned in any of the categories above contain phytochemicals called flavonoids, which help prevent free radical damage and protect against blood clots. Apples, grapes and celery are three of these.

Don’t forget the big picture

Eating more fruits and vegetables fits in with the other recommendations for a heart-healthy diet, such as decreasing intake of fats, sugars and salt. The big picture also includes enjoyment of delicious foods. There are many delicious and easy ways to add fruits and vegetables, most of which are naturally low in fat, to a healthful diet. Including a variety of plant foods in one’s diet will ensure a healthful intake of phytochemicals and contribute to a heart-healthy lifestyle.

Barbara A. Brehm, Ed.D., is professor of exercise and sport studies at Smith College, Northampton, Mass.