💪 Muscles

Muscles are the body's contracting tissues, and their contractile proteins are actin and myosin. To build its own proteins, the body needs protein from food, and milk supplies it: 100 g of whole cow's milk has 3.27 g of protein (USDA). EU law allows the claim that protein contributes to a growth in muscle mass and to its maintenance.

About four fifths of milk protein is casein, and the rest is mostly whey proteins; all the essential amino acids are present in milk proteins (Tetra Pak handbook). Whey protein as a supplement is separated from whey, a by-product of cheesemaking, mainly by membrane filtration. Whole milk also has 60 kcal, 3.2 g of fat, 4.63 g of carbohydrates and 123 mg of calcium per 100 g (USDA).

EU Regulation 432/2012 permits two claims for food that is at least a source of protein: protein contributes to a growth in muscle mass and to its maintenance (based on a 2010 EFSA opinion). Under Regulation 1924/2006, a "source of protein" provides at least 12% of its energy from protein, and "high protein" at least 20%. Whole milk gets about 22% of its energy from protein (a calculation from USDA data).

Milk protein or whey protein powder? Milk gives protein in its natural mix: about four fifths casein, the rest mostly whey proteins, with all the essential amino acids. Whey protein powder is made differently: the proteins are separated from whey, a by-product of cheesemaking, and concentrated mainly by membrane filtration. Milk or soy drink? Whole milk has 3.27 g of protein per 100 g, unsweetened soy drink with calcium 2.86 g (USDA). In both cases the law says protein “contributes” to muscle mass, which is different from promising that a product will build it.

Read the protein per 100 g on the label first. EU rules allow “source of protein” when at least 12% of the energy comes from protein, and “high protein” at 20% or more; whole milk gets about 22% (a calculation from USDA data). Only food that is at least a source of protein may carry the claim that protein contributes to a growth in muscle mass and its maintenance. Milk and yogurt sit in the supermarket dairy chiller, while whey powders are sold as food supplements, often in sports-nutrition shops.

Why it matters to you. Notice the verb "contributes": the law does not promise that a glass of milk or a powder will build muscle by itself. To compare products, look at the protein per 100 g on the label: whole milk has 3.27 g, unsweetened soy drink with calcium has 2.86 g (USDA).