Dear Eating Right: After reading an article in The Times about diet and Recommended Dietary Allowances, I have a question concerning vitamin pills and their labels. Based on the information on the labels, some vitamins supply more than 1,666% of the "U.S. Recommended Daily Allowance." How is this different from the Recommended Dietary Allowances referred to in the article?
--PHILIP RICHARDS, Malibu
Dear Philip: There is a great difference between the two.
The first Recommended Dietary Allowances were developed during World War II when many Americans were found to be malnourished. To make sure the allowances would safely cover most healthy people, suggestions for daily nutrient needs were set high enough to cover people of all ages.
But since that time, suggested levels have been raised or lowered according to the latest scientific research. Advice for nutrients is now given by age group: infants and children are separated from men and women. The RDA table has also been expanded; the 10th and most current edition, published in 1989, gives recommendations for protein, 11 vitamins and seven minerals. The committee added two new nutrients: Vitamin K for its role in normal blood clotting and the trace mineral selenium, which may contribute to heart health.
Another difference: In most cases, the RDA table lists nutrients in milligrams (although micrograms are occasionally given). On the other hand, the U.S. Recommended Daily Allowances (USRDA) are listed as percentages. This is because they were developed primarily for use on product labels and vitamin pills, so that all the RDAs wouldn't have to be printed. They represent the highest RDA of a given nutrient. (As part of the Food and Drug Administration's proposed food labeling changes, the USRDA will be replaced by the terms Reference Daily Intake and Daily Reference Values.)
For example, the RDA of Vitamin A for a woman is 800 retinol equivalents (RE), whereas a man's is 1,000. Instead of reading that a serving of food contains "800 RE" of Vitamin A, it is expressed as a percentage of the RDA or 80%.
Vitamin pills are a little different. This is because vitamins are a concentrated form of nutrients and the RDAs are intended to be met by the nutrients in food. A brand of Super B complex may contain 100 micrograms of Vitamin B-12. This supplies more than 1,000% of the USRDA for that nutrient because the RDA is just 2 micrograms.
Keep in mind that both are recommendations for good health, not requirements , and are aimed at helping you estimate the adequacy of your diet. Neither should be used if you have medical problems which might cause your nutrient needs to vary.
One good way to meet the RDA for nutrients is to include lots of fresh fruits and vegetables in your diet. Garlic enhances the flavor of tomatoes, zucchini, mushrooms and onion, which top a whole-wheat crust in this Fresh Vegetable Pizza.
FRESH VEGETABLE PIZZA
1 package dry yeast
1 teaspoon sugar
1/2 cup warm water
3 large cloves garlic
3/4 cup sifted all-purpose flour
1/2 cup plus 2 tablespoons sifted whole-wheat flour
1 tablespoon oil
1 teaspoon salt
3 small firm-ripe tomatoes
1 cup thinly sliced zucchini
1 cup sliced mushrooms
1/4 cup sliced green onions
1 cup shredded part-skim mozzarella cheese
2 teaspoons fresh minced basil
1/2 teaspoon dried Italian herbs, crumbled
2 tablespoons grated Parmesan cheese
Sprinkle yeast and sugar over warm water and let stand 5 minutes to soften. Peel and press 1 clove garlic through garlic press. Add to yeast along with all-purpose flour. Beat until smooth. Stir in oil and 1/2 teaspoon salt. Gradually stir in enough wheat flour to make moderately stiff dough.
Turn out onto floured board and knead about 2 minutes until smooth. Press dough onto greased 12-inch pizza pan, covering entire pan. Let dough stand.
Scald tomatoes by dropping into boiling water. Let stand 10 seconds. Lift out and strip off skins. Remove cores and cut tomatoes into slices about 3/8-inch thick (enough to measure 2 cups). Drop zucchini slices into boiling water and cook 1 minute. Plunge into cold water, then drain well. Combine zucchini with mushrooms and green onions. Press remaining garlic over vegetables. Mix well.
Sprinkle 3/4 cup cheese over dough. Spoon half of vegetables over cheese-covered dough. Arrange tomato slices on top, overlapping, if necessary. Top with remaining vegetables. Sprinkle with herbs, remaining 1/2 teaspoon salt, mozzarella and Parmesan cheeses. Let stand about 15 minutes or until dough edges feel light to touch.
Bake below center of oven at 375 degrees 30 to 40 minutes or until edges are browned. Serve warm. Makes about 6 servings.
RECOMMENDED DIETARY ALLOWANCES
Children Males Females Pregnant Type of Vitamin 7-10 25-50 25-50 Females Fat-Soluble Vitamins Vitamin A (retinol equivalents) 700 1,000 800 800 Vitamin D (micrograms) 10 5 5 10 Vitamin E (milligrams) 7 10 8 10 Vitamin K (micrograms) 30 80 65 65 Water-Soluble Vitamins Vitamin C (milligrams) 45 60 60 70 Folate (micrograms) 100 200 180 400 Vitamin B-12 (micrograms) 1.4 2 2 2.2 Minerals Calcium (milligrams) 800 800 800 1,200 Iron (milligrams) 10 10 15 30 Zinc (milligrams) 10 15 12 15 Selenium (micrograms) 30 70 55 65
Source: Food and Nutrition Board, National Research Council, Revised 1989