Fruit and vegetables: their importance in the American diet

Food Review, Jan-June, 1992 by Joanne F. Guthrie, Claire Zizza, Nancy Raper

Fruit and vegetables play an important role in the American diet. They are good sources of many essential vitamins and minerals, low in fat, and high in dietary fiber and complex carbohydrates.

Encouraging fruit and vegetable consumption is a major emphasis of the Federal Government's dietary guidance policy. "Choose a diet with plenty of vegetables, fruits, and grain products," is one of the seven basic recommendations of the Dietary Guidelines for Americans, the official statement of Federal dietary guidance policy, which is published jointly by the U.S. Department of Agriculture (USDA) and the Department of Health and Human Services (DHHS) (see "Animal Products: Their Contribution to a Balanced Diet," elsewhere in this issue). Since the early 1900's, food guides from USDA have urged Americans to include plenty of fruit and vegetables in their daily diet.

Yet consumption of fruit and vegetables continues to fall below recommended amounts. To address this problem, public and private organizations are instituting programs aimed at consumer education. Nutrition labeling may also increase consumers' awareness of the nutritional value of fruit and vegetables and promote consumption.

Use of Fruit and Vegetables Up

Since the 1970's, the overall "use" of fruit and vegetables has increased--especially fresh noncitrus fruit, such as bananas, grapes, apples, avocados, pineapples, and strawberries, as well as certain fresh vegetables, including lettuce, onions, tomatoes, carrots, cauliflower, and broccoli.

Among the processed products, the quantity of vegetables used for freezing has increased, while that used for canning has declined.

Potato use has increased due to the popularity of frozen french fries. Americans also are drinking more fruit juices, especially orange juice.

Important Contributors of Vitamins and Minerals

Estimates of nutrients available from the U.S. food supply and the nutrient contribution of major food groups are calculated by nutritionists at USDA's Human Nutrition Information Service (HNIS).

Fruit and vegetables are important sources of numerous vitamins and essential minerals, as well as dietary fiber, while providing little fat and calories. In 1988, for example, fruit and vegetables accounted for only 8 percent of the calories and 1 percent of the fat in the American food supply, while providing 94 percent of the carotenes and 90 percent of the vitamin C.

Vitamin A, Carotenes

Although retinol--the essential nutrient known as vitamin A--is found only in animal foods, plant foods contain compounds called carotenes that can be converted to retinol or vitamin A in the body. Therefore, foods containing carotenes are considered a source of vitamin A.

Vitamin A has long been known to be essential to normal vision, as well as other physiological functions. There has been recent interest in carotenes as a separate dietary component, because some research findings indicate that foods high in carotenes may protect people against some forms of cancer.

Vegetables, especially dark-green and deep-yellow types, are the major sources of carotenes, providing 88 percent of the total supply in 1988. Fruit, especially deep-yellow fruit like cantaloupe and dried apricots, are also good sources of carotenes.

USDA food consumption survey data from 1985 indicate that average diets of adult men and women (age 19-50 years) met the Recommended Dietary Allowance (RDA) for vitamin A, as established by the National Academy of Sciences (NAS). However, data from surveys conducted by the U.S. Department of Health and Human Services indicate that low-income young children, particularly those of TABULAR DATA OMITTED Mexican-American background, may be at risk of low vitamin A status.

Vitamin C

Fruit and vegetables provided approximately 90 percent of the vitamin C in the food supply in 1988. Citrus fruit provided the largest share, 27 percent.

Most Americans consume their RDA for vitamin C. However, low intakes may be a concern for certain groups. Cigarette smokers, in particular, appear to need more vitamin C than do nonsmokers. NAS recommends that smokers consume at least 100 milligrams of vitamin C per day, compared with the RDA of 60 mg/day for adult nonsmokers. Yet USDA survey data indicate that in 1985 adult female smokers consumed an average of 64 mg/day of vitamin C.

Vitamin B-6

Vegetables contributed 22 percent of the vitamin B-6 in the food supply in 1988. White potatoes contributed over half the amount from vegetables. Fruit provided an additional 10 percent of the total supply.

Some population groups consumed lower-than-recommended levels of vitamin B-6. According to USDA survey data, average vitamin B-6 intakes of men and women age 19-50 years were below the RDA in 1985.

Folacin

Folacin is a B vitamin essential for healthy red blood cell formation and formation of genetic material (DNA). Adequate folacin intake is particularly important for a healthy pregnancy--a pregnant woman's RDA for folacin is more than double that of a woman who is not pregnant. Using USDA survey data collected in 1985 and 1986, HNIS researchers found that average intakes of folacin for pregnant women age 19-39 years were higher than those of nonpregnant women--but not high enough to meet their RDA.