Breastfeeding and eczema

A baby’s microbiome and the impact on their immune development

The development of our immune system is perhaps the most essential of all. As well as being fundamental to survival and ongoing development, it plays a huge part in the nature of allergic disease.

The ‘microbiome’ is a community of all of the bacteria, viruses and fungi that are found in the human body. The human gut alone is made up of 100 trillion microbes and has as many as 5,000 different species.

The newborn baby was once thought to be microbiologically sterile and its first exposure to its new bacterial environment, the world outside the womb, was contact with the vaginal and faecal bacteria of the mother, or, for caesarean section births, the hospital environment.

This process is known as seeding and this exposure creates colonies of microflora in the baby’s gut. The nature of that flora, and the baby’s immune system’s adaptation to it, is critical to their immune development.

How your baby is born creates differences in your baby's microbiome.

There is a difference in the microbiome of a baby depending on how they are born.

Babies that are born by caesarean section have less of a type of bacteria called bifidobacteria at 1 month old compared to those born vaginally.

By the time your baby is 6 months old and weaning begins, these differences are less apparent but baby’s born by caesarean section have greater levels of immune cells (IgA, IgG, and IgM) until they are at least 12 months ago, suggesting that lower numbers, and type, of initial colonising bacteria may hinder immune development during a critical period of development.

Breastfeeding and formula feeding

How you choose to feed your baby is a personal choice but the affect on a baby’s flora is significant. Bifidobacteria dominate the microbiota of breastfed infants, whereas formula-fed infants have higher proportions of Bacteroides and members of the Clostridium and Lactobacillus groups.

At 12 months, the bacterial populations of both breast and formula-fed infants begin to resemble those of adults. The difference in development of this microbiota is highly significant for immune development.

Immune Tolerance

One of the first challenges the newborn baby faces is to develop an appropriate immunological response to its environment. The presence of ‘friendly’, non-self bacteria in the microbiota is critical to facilitating this process. On the one hand the baby needs to develop immune tolerance of certain substances such as pollens and dietary antigens. On the other it needs to react appropriately to genuine threats from pathogenic bacteria or viruses.

Secondly, appropriate differentiation of types of antigen by the immune system needs to develop. This is programmed first and foremost by the gut immune system through a process called ‘Bystander Suppression’. Friendly bacteria such as Lactobacilli stimulate the immune cells in the gut to produce regulatory cytokines to ensure they are tolerated. If there is continued exposure to environmental antigens, such as allergenic foods, the activation of these regulatory cytokines will also prevent the unrelated allergen from being processed through the correct immune pathway. This oral tolerance is vital to normal immune development and disruption can skew the system in favour of allergies or autoimmunity, both in essence being a result of unaltered immune responses to harmless antigens.

Breastfeeding and milk composition

As well as delivering key nutrients to the infant, breastfeeding plays a major part in immune development, training the immune system in a number of ways. Breast milk contains immunoglobulins, lysozyme, lactoferrin, prebiotics and probiotic bacteria like Lactobacilli and Bifidobacteria.

In addition to bacteria being transferred through direct contact with skin, there may be an internal transportation of bacteria via dendritic cells and macrophages from the maternal gut to the mammary gland. Thus milk composition is a reflection of the current environment and maternal immune response and acts as an adaptive ‘immune imprinting’ for the baby. Breast milk also has antimicrobial and anti-inflammatory properties and contains growth factors that promote development of the epithelial structure of the gut wall.

Eczema - an autoimmune condition

When we start to understand eczema as an autoimmune condition rather than just a skin condition it becomes apparent the importance of gut health, the development of allergic disease and the intricate relationship the gut has with the immune system.

For personalised advice and support for your own or your child’s health please book an appointment, I’d love to work with you.