Milk proteins (like proteins of animal sources in general) contain, in the right proportions, all essential amino acids that your body can not produce itself. They can thus be considered as ‘complete’. On the contrary, plant proteins do not contain all essential amino-acids. Cereal proteins do not contain lysine, pulses do not contain methionine.

* If the deficiency does not relate to the same amino-acid, certain foodstuffs can complement each other; semolina and chickpeas, maize and beans, rice and lentils.