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Back to Protein

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.


  1. 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.
  2. 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.
  3. Schaafsma G. The Protein Digestibility-Corrected Amino Acid Score . J Nutr 2000;130:1865S–1867S.
  4. Miller GD et al. Handbook of dairy foods and nutrition, 3rd ed. Boca Raton, FL: CRC Press, 2007.
  5. Health Canada. Canadian nutrient file (CNF) , 2007. Accessed June 28, 2010.

Keywords: protein

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