Milk Proteins

The protein makeup of breast milk and infant formula

Protein sources

Adults can get protein from many different food sources but young babies are totally reliant on breast milk or Infant formula to supply all of their nutritional needs. The protein composition of their milk or formula is therefore crucial to their healthy growth and development.

Breast milk protein

Mature breast milk consists of two main types of protein:

40% Casein (less soluble, tends to stay longer in the stomach)¹
60% Whey (more soluble, relatively easy to digest)¹
- The main whey protein in mature breast milk is alpha-lactalbumin (alpha protein)
- Breast milk contains 27% alpha protein, 0% beta-lactoglobulin (beta protein) and 33% other whey proteins ^2,3
- These alpha protein contains a high proportion of essential amino acids

Infant Formula protein

Like breast milk, most infant formulas are whey-dominant.

Most typical whey-dominant infant formulas consist of:

40% Casein (less soluble, tends to stay longer in the stomach)¹
60% Whey (more soluble, relatively easy to digest)¹
- Unlike breast milk, the major whey protein in most typical whey dominant infant formula is beta protein
- Beta protein is found in cows' milk, and not usually in breast milk
- Most typical whey-dominant infant formulas contain 11% alpha protein, 29% beta protein and 20% other whey proteins ^2,3
- It is believed that beta protein is particularly antigenic, with the potential to contribute to cows’ milk protein intolerance in infants ^4,5

SMA First Infant Milk protein

Unlike most whey-dominant infant formulas, SMA First Infant Milk contains more alpha protein and less beta protein. This means it has the closest whey protein profile to that of breast milk, making it the best choice for bottle-fed babies, or for combination feeding. ^2,3

SMA First Infant Milk consists of:

35% Casein (less soluble, tends to stay longer in the stomach)
65% Whey (more soluble, relatively easy to digest)
- Like breast milk, the major whey protein in SMA First Infant Milk is alpha protein
- Because the quality of alpha protein is high, SMA have been able to reduce the overall quantity of protein in SMA First Infant Milk, helping reduce the burden on infants’ kidneys, and supporting growth and development

SMA First Infant Milk is supported by new clinical evidence, showing that babies fed the formula gained weight at a rate closer to that of breastfed infants than a standard formula.⁶

References

Lawson M. Contemporary aspects of infant feeding. Paediatric Nursing 2007; 19: 39-45.
Lien EL et al. Growth and safety in term infants fed reduced-protein formula with added bovine alpha-lactalbumin. Journal of Pediatric Gastroenterology and Nutrition 2004; 38: 170-16.
Lien EL. Infant formulas with increased concentrations of alpha-lactalbumin. American Journal of Clinical Nutrition 2003; 77(6): 1555s-1558s.
Selo et al. Allergy to bovine β-lactoglobulin: specificity of human IgE to tryptic peptised. Clinical and Experimental Allergy, 1999, 29: 1055-1063.
Heine WE et al. The importance of α-lactalbumin in infant nutrition. Journal of Nutrition 1991; 121(3): 277-283.
Trabulsi J et al. The effect of two different protein concentrations in term infant formula on growth. Abstract presented at ESPGHAN June 2009.