How does the protein content of cow’s milk and plant-based milk alternatives compare?
Cow’s milk and plant-based dairy alternatives differ considerably with regard to the amount and quality of protein present per 100 ml. Plant-based beverages contain very little protein – usually only 1 g per cup, compared to 8 g in a cup (250 ml) of cow’s milk.
Protein quality has a notable effect on the nutritional quality of a dietary protein source. Cow’s milk is also naturally high in “complete” protein (providing all essential amino acids), whereas plant-based milk substitutes contain mostly “incomplete” protein. Owing to the ratio of essential amino acids in animal-derived protein, the protein in cow’s milk has a higher bioavailability than that of plant-based milk substitutes. For example, the nutritive value of soy protein is limited by its lower content of methionine and cysteine. Therefore, when plant-based protein is used, more total protein must be consumed for the body to get enough of the amino acids it needs. Refer to the table on nutrient comparisons for details.