Infant Formula Proteins: Regulations, Types & Uses

Regulatory Requirements

Infant formulas must meet strict regulatory standards to ensure they provide safe and adequate nutrition for babies. Key requirements include:

• Minimum and maximum protein levels to support healthy growth.

• Essential amino acid requirements based on the composition of breast milk.

All approved formulas must meet these standards. Some products also add specific amino acids to ensure compliance.

Types of Protein in Infant Formula

Cow’s Milk Protein
Cow’s milk protein is the most common and well-studied protein used in infant formulas. Some formulas specify the ratio of whey to casein proteins:

• Whey protein digests quickly.

• Casein digests more slowly, forming a curd in the stomach that can help babies feel full longer.

For reference, breast milk typically has a 60:40 ratio of whey to casein, which matures to approximately 50:50 over time.

A2 Cow’s Milk Protein
A2 formulas contain only the A2 variant of beta-casein protein.

Goat’s Milk Protein
Goat’s milk protein has a slightly different structure from cow’s milk protein. Some evidence suggests it may digest more easily and may be tolerated by some sensitive infants with mild digestive discomfort.

However, due to protein similarities, goat’s milk formulas are not suitable for infants with a diagnosed severe cow’s milk protein allergy. A 2023 systematic review found no clear advantages compared with standard cow’s milk formulas (source). 

Soy Protein
Soy protein, made from soy protein isolate, is a plant-based alternative to cow’s milk protein. Soy formulas have been safely used for decades world wide. Typically, these formulas are recommended for infants over six months for babies who cannot tolerate cow’s milk protein, provided there is no soy allergy. 

Hydrolysed Whey Protein
Hydrolysed whey protein formulas break down protein into smaller fragments, which may make digestion easier. The degree of hydrolysis (protein breakdown) varies between formulas. The absence of casein protein may make these formulas easier to tolerate for some babies, as casein is normally the cause of cow's milk allergy. 

• Partially hydrolysed whey: Broken down moderately; often marketed as “sensitive” or “premium” formulas, widely available without prescription.

• Fully hydrolysed whey: Extensively broken down; should be used under medical supervision for mild to moderate cow’s milk allergy .

Rice Protein
Hydrolysed rice protein formulas, often with added amino acids, are specialty formulas for babies with cow's milk or soy allergies. They should be used under medical supervision.

Rice & Pea Protein Blend

Hydrolysed rice and pea protein blend formulas include added amino acids to meet nutritional requirements and may be a suitable alternative to dairy-based formulas. As a relatively new option in infant nutrition, these formulas are not yet widely available worldwide. 

Amino Acid Formulas
Amino acid formulas contain individual amino acids and are hypoallergenic. They are designed for infants who cannot tolerate intact or hydrolysed proteins, such as those with severe cow’s milk protein allergy or multiple food protein intolerances. These formulas are expensive and are prescribed under medical supervision only when other options are not tolerated.