Milk Products: Source of High-Quality Protein
Milk products are a source of protein, but what about the quality of protein?
Milk contains two types of protein: whey (20%) and casein (80%). Both are high-quality proteins, according to science-based rating scales, and both contain all essential amino acids in amounts sufficient to support the multiple roles of protein in the body.1,2
According to the Protein Digestibility-Corrected Amino Acid Score (PDCAAS), a method of measuring protein quality based on availability of essential amino acids as well as digestibility, milk provides higher-quality protein than beef, soy or wheat.3 Because of its high quality, cow’s milk protein is used as a standard reference protein to evaluate the nutritive value of food proteins.4
Protein Content of Various Foods and Beverages5
|Food Group||Food||Protein Content|
|Meat and Alternatives||Beef sirloin steak, 75 g||26 g|
|Tofu, firm, raw, 75 g||21 g|
|Pork tenderloin, 75 g||21 g|
|Chicken, skinless breast, 75 g||20 g|
|Tuna, canned light, 75 g||19 g|
|Eggs, whole cooked, 2 large||13 g|
|Kidney beans, boiled, 175 mL (¾ cup)||12 g|
|Lentils, boiled, 175 mL (¾ cup)||13 g|
|Almonds, 60 mL (¼ cup)||8 g|
|Milk and Alternatives||Cottage cheese, 125 mL (½ cup)||15 g|
|Cheddar cheese, 50 g (1¾ oz)||12 g|
|Milk, 250 mL (1 cup)||8 g|
|Yogurt, 175 mL (¾ cup)||8 g|
|Grain Products||Whole-wheat pasta, cooked, 125 mL (½ cup)||4 g|
|Whole-wheat bread, 1 slice||3 g|
|Brown rice, cooked, 125 mL (½ cup)||3 g|
|Oatmeal, prepared, 175 mL (¾ cup)||3 g|
|Vegetables and Fruit||Potato, with skin, cooked, 125 mL (½ cup)||5 g|
|Broccoli, cooked, 125 mL (½ cup)||2 g|
|Butternut squash, cooked, 125 mL (½ cup)||1 g|
|Banana, raw, 1 medium||1 g|
|Apple juice, bottled, 125 mL (½ cup)||0 g|
Bolded foods indicate high-quality, complete protein sources.
- Phillips SM et al. The role of milk- and soy-based protein in support of muscle protein synthesis and muscle protein accretion in young and elderly persons . J Am Coll Nutr 2009;28(4):343–354.
- Bos C et al. Nutritional and physiological criteria in the assessment of milk protein quality for humans . J Am Coll Nutr 2000;19(2):191S–205S.
- Schaafsma G. The Protein Digestibility-Corrected Amino Acid Score . J Nutr 2000;130:1865S–1867S.
- Miller GD et al. Handbook of dairy foods and nutrition, 3rd ed. Boca Raton, FL: CRC Press, 2007.
- Health Canada. Canadian nutrient file (CNF) , 2007. Accessed June 28, 2010.