Protein should account for 10 to 35 percent of your daily calories. With 4 calories in each gram, this amounts to 50 to 175 grams of protein on a 2,000-calorie-per-day diet. Eating dairy products is a good way to meet your daily protein needs. In addition to being high in protein, most dairy products are excellent sources of vitamins and minerals that are important for bone health, including vitamin D, calcium, phosphorus and potassium.
Skim milk is a good source of protein, with a 1-cup serving providing 8.3 grams. In comparison, a 1-ounce serving of low-fat mozzarella cheese contains 6.9 grams, and 1 ounce of cottage cheese contains 3.5 grams. Ice cream also contains a modest amount of protein, with 3.6 grams in a 1/2-cup serving of light vanilla ice cream. In contrast with the high concentrations in most dairy products, butter contains only 0.1 grams of protein in 1 tablespoon, which is approximately equivalent to a half ounce.
Most of the calories in dairy products come from their fat and carbohydrate contents. This results in some dairy products having a much higher ratio of calories to protein than others. Skim milk and low-fat mozzarella, for example, both contain approximately 10 calories for each gram of protein. Cottage cheese is more protein-dense, with 6 calories for each gram of protein. Because of its high sugar content, light vanilla ice cream contains nearly 38 calories for each gram of protein. Butter, which is mostly calorie-rich fats, provides well over 800 calories for each gram of protein. As such, skim milk and cottage cheese are among the best dairy sources of protein.
Most of the protein in dairy products comes in the form of casein. This protein is an excellent natural source of essential amino acids. Unlike the 11 non-essential amino acids, your body cannot produce these important compounds. As such, your essential amino acid intake is at least as important as your total protein intake. Because they provide a good source of all nine essential amino acids, some dairy products are considered "high-quality" or "complete" proteins. Even if you were to obtain all of your protein from milk, for example, you would meet your daily essential amino acid needs with as little as 5 cups per day.
Low-fat and non-fat dairy products typically differ from whole-milk products only in their fat and caloric content. By choosing skim milk over 2 percent milk, for example, you can obtain the same amount of protein with approximately two-thirds the calories. Despite these differences, you should not rely solely on dairy products to meet your protein needs. Although they are good sources of protein and essential amino acids, dairy products are not naturally high in many of the micronutrients present in other protein sources. To ensure that you obtain an adequate amount of vitamins and minerals, the 2010 "Dietary Guidelines for Americans" recommends that you eat a variety of animal and plant sources of protein every day.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services; Dietary Guidelines for Americans, 2010
- U.S. Department of Agriculture National Nutrient Database for Standard Reference: Milk, Nonfat, Fluid, With Added Vitamin A and Vitamin D (Fat Free or Skim)
- U.S. Department of Agriculture National Nutrient Database for Standard Reference: Cheese, Mozzarella, Part Skim Milk
- U.S. Department of Agriculture National Nutrient Database for Standard Reference: Cheese, Cottage, Lowfat, 1 Percent Milkfat
- U.S. Department of Agriculture National Nutrient Database for Standard Reference: Ice Creams, Vanilla, Light
- U.S. Department of Agriculture National Nutrient Database for Standard Reference: Butter, Without Salt
- University of Illinois Animal Sciences: Milk Composition: Proteins
- Vegan Health: Protein
- U.S. Department of Agriculture National Nutrient Database for Standard Reference: Milk, Reduced Fat, Fluid, 2% Milkfat, With Added Vitamin A and Vitamin D
- Milk image by Eisenhans from Fotolia.com