The United States government publishes guidelines for appropriate nutrient intakes These are known as the Recommended Dietary Allowances (RDAs) and are updated regularly based on new research in the science of nutrition. RDAs are suggested amounts of calories, protein, and some minerals and vitamins for an adequate diet. For other dietary substances, specific goals must await further research. However, for the U.S. population as a whole, increasing starch and fiber in our diets and reducing calories (primarily from fats, sugar, and alcohol) is sensible. These suggestions are especially appropriate for people who have other factors for chronic diseases such as family history of obesity, premature heart disease, diabetes, high blood pressure, and high blood cholesterol, or for those who use tobacco. Snacks can furnish about one-fourth of the calorie requirements among teenagers Those snacks should also furnish much of the day's allowances for protein, minerals, and vitamins. Sa
A. New discoveries in the science of nutrition are constantly being made.
B. Americans' diets are constantly changing.
C. As people age, their nutritional needs change.
D. Very little is currently known about nutrition.
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