The United States Department of Agriculture is responsible for making health recommendations for American diets. The USDA publishes a list of recommended daily intake for nutrients, vitamins and minerals. Although every person's nutritional needs are different, the USDA makes recommendations based on a theoretical "average" American.
Assumptions
The USDA dietary intake recommendations are based on specific assumptions about a person's age, gender and activity level. You can find very specific recommendations for dozens of categories and subcategories in USDA publications. However, the recommendations on food labels are based on an "average" American with a moderate level of activity and eating 2,000 calories per day.
Macronutrients
The USDA identifies fats, carbohydrates and proteins as "macronutrients" -- sources of the calories your body burns and the basic building blocks for tissues. For the average American diet, the USDA recommends taking in 50 g of protein, 300 g of carbohydrates and 50 g of fat. However, the kinds of macronutrients are as important as the amount. It's healthier to eat whole-grain carbohydrates than refined grain carbohydrates, and to get your fat from plant sources as much as possible. As for proteins, "complete proteins" -- most commonly from animal sources -- provide more of the essential amino acids your body needs than those from most plants.
Vitamins
The vitamins in your foods contribute to different processes in your body, each in its own unique and specific way. The USDA makes specific recommendations for six classes of vitamins. Each day you need 900IU of vitamin A, 90mg of vitamin C, 5 mg of vitamin D, 15 mg of vitamin E and 120 mcg of vitamin K. Several different categories of B vitamins have their own recommended intake. You need 1.2 mg daily of vitamins B-1, 1-2 and B-6; 16 mg of B-3 and 2.4 mg of B12. When consulting the nutrition label on a food package, you will find its vitamin content listed both in raw numbers and as a percentage of your reference daily intake.
Minerals
Like vitamins, minerals play a role in the healthy functioning of your body by enabling or encouraging body processes. Also like vitamins, you will find the mineral content in food on your nutrition labels, listed both as a percentage and as a raw total. Given a 2,000 calorie-per-day diet, the USDA makes the following recommendations for 15 dietary minerals: 1,200 mg of calcium, 30 IU of chromium, 900 mg of copper, 3 mg of fluoride, 150 IU of iodine, 8 mg of iron, 420 mg of magnesium, 2.3 mg of manganese, 45 IU of molybdenum, 700 mg of phosphorus, 55 IU of selenium, 11 mg of zinc, 4.7 g of potassium, 1.3 g of sodium and 2.3 g of chloride.
References
- "National Nutrient Database for Standard Reference"; U.S. Department of Agriculture; 2009
- "Eat, Drink and Be Healthy"; Walter Willett MD, et al; 2006
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