This site is intended for Healthcare Professionals only

8. Key ingredients of milks

Breastfeeding bookmark icon off

8. Key ingredients of milks

The following ingredients are present in both breast and infant formula milks to ensure babies get all the nutrients they need to thrive

Fats

Due to their fast growth rate, babies require three to four times more energy per kilogram of body weight than adults. Fat contains lots of calories and is a very concentrated source of energy, accounting for half the energy content of breast milk. This high energy density is important as babies have a limited stomach capacity.

Fat also acts as the carrier for the fat-soluble vitamins A, D, E and K. Breast milk and most infant formula milks also contain essential fatty acids and long-chain polyunsaturated fatty acids (LCPs), including arachidonic acid (AA) and docasahexaenoic acid (DHA).

DHA is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex and retina. Research has shown that it is important for the normal visual development of infants. The February 2020 legislative changes to infant formula milks mean that the addition of DHA to infant formula milks is now a mandatory requirement in the range 20-50mg/100kcal.

The February 2020 legislative changes to infant formula milks mean that the addition of DHA to infant formula milks is now a mandatory requirement

Carbohydrates

Carbohydrates include sugar, starch and cellulose and are typically broken down to release energy into the body. The main carbohydrate is lactose, a natural milk sugar that provides 40 per cent of the energy content of breast milk. Breast and infant formula milks also contain oligosaccharides – a type of carbohydrate consisting of linked sugar units. Examples of these include fructo- and galacto-oligosaccharides.

Probiotics and prebiotics

Prebiotics are non-digestible oligosaccharides (carbohydrates) that stimulate the growth of so-called friendly bacteria – or probiotics – in the gut. These are live bacteria and yeasts that can change the gut’s bacterial balance. Probiotics help to push food through the gut and keep the digestive tract healthy. Some clinical trials suggest that probiotics may also have a role in supporting gastrointestinal health in healthy children, potentially helping to treat things like irritable bowel syndrome, inflammatory bowel disease, diarrhoea, colic and eczema. 

Prebiotic oligosaccharides are the third most prevalent component of breast milk but are virtually absent in cows’ milk, which is why they are often added to infant formula to mimic the benefits. Research shows that differences in the bacterial balance in the gut and incidence of infection exist between breast-fed and formula-fed infants, with the former thought to have improved protection. Whether this supplementation of prebiotic oligosaccharides in formula milk is as beneficial as natural prebiotics in breast milk is still being debated.

Following significant research and clinical trials, human milk oligosaccharides (HMOs) are now being added to some infant formula milks to try to achieve additional levels of protection for babies. HMOs are complex carbohydrates, also known as targeted prebiotics, uniquely found in breast milk, and research suggests that they play an important role in building a strong immune system in babies. HMOs have a unique structure that allows them to provide targeted benefits for infants in four main ways:

  • Feeding good bacteria within the gut
  • Blocking bad bacteria from attaching to the gut
  • Strengthening the developing gut barrier
  • Helping to balance the immune system.

Research suggests that HMOs play an important role in building a strong immune system in babies

Proteins

Protein is required for the growth and maintenance of muscles and bones. Casein and whey are the two main proteins, which occur in breast milk in a ratio of 40:60. 

  • Whey protein forms an easily-digestible soft curd. In breast milk, whey protein also contains other important proteins: lactoferrin, lysozyme, alpha-lactalbumin and immunoglobulins   
  • Casein protein has coagulating properties, so forms a firmer curd that may take longer to digest.

Nucleotides are proteins that form the building blocks of DNA. They are found in breast milk and play a key role in many biological processes, including energy transfer. At times of rapid growth or in disease, the body may not be able to produce nucleotides at the rate they are required and so must rely on dietary sources. 

Studies suggest that dietary nucleotides have a role to play in both the immune and gastrointestinal systems, having a protective effect. While nucleotide-supplemented formula feeding has not been shown to confer the same benefits as breastfeeding, and their inclusion is not mandatory, it is thought that nucleotides may help to support growth in some formula-fed infants.

Vitamins

  • Vitamin A: contributes to normal immune system function, maintenance of normal vision and skin, and helps the body metabolise iron
  • Vitamin D: needed for calcium absorption, it contributes to the normal function of the immune system and helps maintain normal teeth, muscle function and bones
  • Vitamin E: helps to protect cells from oxidative stress
  • Vitamin K: helps maintain normal bones and blood clotting
  • Vitamin C: contributes to normal immune and nervous system function. Increases iron absorption 
  • B vitamins: important for energy metabolism.

Minerals

  • Calcium: needed for the maintenance of normal bones and teeth, and contributes to normal blood clotting, muscle function and the heart beating
  • Phosphorus: contributes to the maintenance of normal bones and teeth
  • Zinc: contributes to normal cognitive function, the metabolism of fatty acids and vitamin A, and the maintenance of normal bones, vision and immunity
  • Selenium: protects cells from oxidative damage
  • Iodine: important for growth and normal cognitive function
  • Iron: contributes to normal cognitive function.

The iron content of breast milk is low as babies are generally able to rely on their own stores until four to six months of age. At this point, babies need a dietary source of iron. Iron is more efficiently absorbed from breast milk than infant formula milk, which is why infant formula milk contains higher levels of the nutrient.

Copy Link copy link button

Breastfeeding

Share: