Breast Milk & the Immune System

Our breast milk research focuses on three main areas:

  • Composition
    We know that both the macronutrient and micronutrient composition of breast milk is affected by the diet of mothers. Thus, we study the factors that influence the composition of breast milk, such as culture or geographic dietary habits of the mother, genetic background, disease and the general nutritional health of mums.
  • Structure
    Exploring breast milk fat structure enabled us to recently discover that, for optimal use by growing infants, lipids –a group of naturally occurring fatty acid molecules – need to be available not only in the right composition, but also in the right structure.
  • Functionality
    We study the effect of specific breast milk ingredients on optimal digestion, nutrient absorption and development of gut microbiota, the immune system, brain development, and metabolism in infants.

The Complexity of Breast Milk

As well as being the most natural way to feed infants, breast milk provides the best source of nutrition. Further, research has discovered that breast milk contains many biological components that help to strengthen the developing immune system.

Breast milk is a complex substance, containing the perfect nutritional mixture needed for growth and development including brain and eye development. It provides the best type of nutrition for infants. Breast milk also contains many other unique properties that researchers have found have no nutritional values but exhibit biological and physiological functions which strengthen the developing immune system. These biological and physiological properties are unique to breast milk and some of these are:

Breast Milk Oligosaccharides

Breast milk oligosaccharides are unique and complex components of human breast milk and only traces have been found in the milk of any other species. Being the third largest solid component in human breast milk, these oligosaccharides selectively feed and stimulate the growth and activity of good bacteria in the gastrointestinal system of the infant. This in turn leads to the development of a healthy gut and immune system.


Antibodies which can also be known as immunoglobulins, consist of 5 main forms IgG, IgA, IgM, IgD, IgE. These protective proteins play an important physiological role in the functioning of the immune system as they identify and neutralise foreign objects. An infant starts to acquire antibodies through the placenta prior to birth, however after birth an infant acquires these antibodies through breast milk.

White Blood Cells

White blood cells can also be known as leukocytes. These are cells which form part of the immune system. Their main role is to help to defend the body against foreign materials. Colostrum (the breast milk received in the first few days after birth) contains high amounts of white blood cells which are important for the development of the infant’s immune system.

The Immune System

The immune system is a collection of organs, cells and tissues that work together to protect the body from foreign bodies and potentially harmful organisms. The immune system consists of the gastro-intestinal tract, thymus, spleen, lymph nodes, bone marrow, as well as many specialised cells such as those illustrated.


What is so important about the immune system?

Infants are born with an immature immune system, making them vulnerable during their first few years of life. Most of the immune system lies within the gut, and it is the first line of defence from potentially harmful micro-organisms.

Nutrition plays an important role in supporting the development of the immune system. It is well recognised that breast milk provides the best start in life and is the best nutrition for baby's developing immune system.


Why does my baby's immune system need supporting?

During pregnancy, a baby's gut is sterile and is protected thanks to basic defences like the skin, placenta, amniotic sac and fluid and the supply of their mother’s own antibodies which travel across the placenta. This is known as 'passive' immunity. During a natural delivery, the baby's journey through the birth canal exposes them to their mother’s bacteria which colonises their gut to help support the development of their immune system.

If the mother has a caesarean section, the first bacteria that their baby has contact with comes from the hospital environment rather than the birth canal and differences have been found to exist in the gut flora of babies born by caesarean section.

Whether born naturally or by caesarean, nutritionally supporting a baby’s digestive and immune system is important for their growth and development.