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How Partially Hydrolysed Protein improves tolerance in Preterm feeding

5 mins


Preterm infants have an immature digestive system and often struggle with feeding intolerance when formula fed. Breastmilk is the best source of nutrition for preterm infants

Breastmilk contains its own enzymes (such as plasmin), is well tolerated and leaves the stomach faster than formula1,2

Partially hydrolysed preterm formula may be better tolerated by some preterm infants and may allow better progress to full milk feeds3,4

Adult hand supporting preterm baby feet

Feeding the preterm infant

Feeding preterm infants is a critical aspect of neonatology, successful care of the preterm infant is dependent on these babies receiving the right amount of nutrients while overcoming many challenges in their feeding management such as the need for protein, adjustments for optimal catch-up growth rates5 and the immaturity of their digestive system.

Preterm infants miss out on some key stages of structural development of the gut and therefore, are at risk of feed intolerance and poor nutrient absorption, especially protein. Immature motor function is likely to be the most common cause of enteral feed intolerance in Very Low Birth Weight (VLBW) infants5.

Structural development of the gut

Structural development of the gut

The importance of protein

Protein is critical for growth and development in infancy. Protein is essential not only for body growth but for metabolic signalling. A protein intake of 3.5-4.0 g/kg/day is necessary to produce normal protein balance and growth in very preterm infants6. Ensuring efficient protein breakdown (proteolysis) and utilisation is of great importance.

Expressed breast milk (EBM) is the first choice for feeding preterm infants due to its beneficial effects on digestion, cardiovascular, neurological, bone health and growth outcomes7.

Partially hydrolysed protein in breastmilk8

Breast milk contains both intact protein and hundreds of smaller peptides, this is because breastmilk contains proteolytic enzymes (plasmin) which break the protein chains into smaller pieces that are easier for the infant to digest.

Partially hydrolysed protein in breastmilk

Plasmin is active in the mother’s mammary gland but most of the proteolytic enzymes become active once in the stomach and are intended to help assist an infant’s GI tract with protein digestion8.

Partially hydrolysed protein in formula

To mimic the effect of these enzymes in breast milk, some preterm formulas have been produced with protein that is partially hydrolysed, this means the protein is broken down into smaller pieces with a mixture of protein and smaller peptides for easier digestion and faster GI transit.

The process of hydrolysis of protein in formula

The process of hydrolysis of protein informula

When considering the feeding of preterm infants, it is important to consider not only the need to ensure sufficient growth rates but also the potential abilities/limitations of the infant’s GI tract to effectively digest and absorb nutrients5.

Ease of digestion due to partially hydrolysed protein

Breast milk contains partially hydrolysed proteins for easier digestion and absorption8-9.

The results from a study show how the transit time of whole protein formulas compare to a partially hydrolysed protein formula and to breastmilk.

Partially hydrolysed formulas have been shown to have a gastric emptying time closer to that of breast milk and faster than whole protein formulas, allowing for accelerated feeding advancement3-4,10-11

Transit time of milks through the stomach

Transit time of milks through the stomach


Protein is a major driver of growth and development in infants, and the success of nutritional management largely depends on its effective intake. Considering the presence of peptides in human milk and the combination of enzymes helping to achieve maximal digestion of human milk proteins, the use of partially hydrolysed formula in preterm infants appears quite practical and substantiated5.

SMA Gold Prem® is a range of preterm formulas specially designed to meet the needs of preterm low birth weight infants. It offers a unique combination of nutrients and 100% whey, partially hydrolysed protein for improved tolerance.4,12-14

SMA Gold Prem® range is a food for special medical purposes and must be used under medical supervision.

GI - Gastrointestinal

  1. Amaforte E et al. International Dairy Journal 2010; 20:715-723

  2. Dallas D et al. J Nutr Disord Ther. 2012; 2(3): 112-124.

  3. Mihatsch et al. Acta Paediatr. 2001;90:196-8.

  4. Mihatsch et al., Pediatrics 2002;110(6): 1199-1203

  5. Ukraintsev SE et al. Neonatology. 2019; 7(4):20-25.

  6. William W Hay et al., Neonatology. 2008;94(4):245-54. doi: 10.1159/000151643. Epub 2008 Oct 2.

  7. Kumar RK et al., Front Nutr 2017; 4: 20. Available at

  8. Dallas D et al. J Mammary Gland Biol Neoplasia. 2015;20(0):133–147.

  9. Martin CR et al. Nutrients 2016; 8(5): 279.

  10. Picaud JC. et al. Journal of Paediatric Gastroenterology and Nutrition 2001; 32:555-561.

  11. Billeaud C et al. Eur J Clin Nutr 1990; 44: 577–583

  12. SMA Gold Prem® Breast Milk Fortifier data card.

  13. SMA Gold Prem® 1 data card.

  14. SMA Gold Prem® 2 data card.


We believe that breastfeeding is the ideal nutritional start for babies as breast milk provides a balanced diet and protection against illness for a baby. We fully support the World Health Organizations recommendation of exclusive breastfeeding for the first six months of life followed by the introduction of adequate nutritious complementary foods along with sustained breastfeeding up to two years of age. We also recognize that breastfeeding may not be an option due to certain medical conditions. Parents should only feed Infant formula for special medical purposes under supervision of a healthcare professional after full consideration of all feeding options, including breastfeeding. Continued use has to be assessed by the healthcare professional in relation to the baby's progress bearing in mind any social and financial implications for the family. Infant formula should always be prepared, used and stored as instructed on the label in order to avoid risks to a baby’s health. These products must be used under medical supervision. SMA GOLD PREM® BREAST MILK FORTIFIER is a nutritional supplement designed to be added to expressed breast milk for the dietary management of feeding preterm low birthweight babies. It is NOT a breast milk substitute. SMA Gold Prem® 1 is a special formula intended for the dietary management of preterm low birthweight babies who are not solely fed breast milk. It is suitable for use as the sole source of nutrition for preterm babies from birth. SMA Gold Prem® 1 is not intended for use with older preterm babies, for whom a special catch-up formula such as SMA Gold Prem® 2 is more appropriate. SMA Gold Prem® 2 is a special catch-up formula intended for the dietary management of preterm low birthweight babies who are not solely fed breast milk. It is a nutritionally complete formula for use on discharge from hospital or when a low birthweight formula is no longer appropriate. It is suitable for use as the sole source of nutrition up to 6 months corrected age. SMA Gold Prem® 2 is not intended for use with newborn preterm babies, for whom fortified breast milk or a low birthweight formula such as SMA Gold Prem® 1 is more appropriate.