Protein level requirements differ depending on the type of formula - animal milk, soya or protein hydrolysate. There is a slightly lower minimum level of protein content for follow-on formula compared to infant formula.1

All must, however, contain appropriate levels of each of the amino acids required for life that the body is not able to make itself. The regulations also stipulate the ratios between various amino acids.

In nutritional terms, of the 20 or so amino acids commonly used by the body as building blocks for proteins, several can be made by the body itself. However, eight can only be sourced through diet – these are known as essential or “indispensable” amino acids. There are another seven “conditionally indispensable” amino acids that children’s bodies are unable to make in sufficient quantities (or some adults cannot make at times due to disease state).7

Annex 3 to the 2016 regulations details the “indispensable and conditionally indispensable” amino acids and the required levels to match breast milk for all formulas. For cows’ or goats’ milk and/or soya protein isolate derived formulas, the specified amino acids are: cysteine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, tyrosine, and valine. For protein hydrolysate-based formula, the list adds arginine, as well.1

Infant formula must have a minimum level of L-carnitine, but this is not specified for follow-on formula. The addition of taurine, an amino sulfonic acid required for retinal and brain development, is optional for infant and follow-on formula.1,8