Immune system training

The importance of intestinal flora during infancy

In the right composition, the bacteria in our intestine promote good health. They break up indigestible nutrients from our food, supply us with vitamins and train the immune system. Bacterial colonisation in an unborn child starts in the womb. During birth and the first few years of life, an ecosystem of gigantic proportions gradually develops. If the balance of the bacterial community is disrupted, the far-reaching consequences can have an impact on the child's health.

Although the micro-organisms which colonise us only make up one to three percent of our bodyweight, they outnumber our cells several times over. One hundred billion microbial cells colonise the human body – that's ten times more microbial cells than human body cells. The intestinal flora stay with us throughout life and are therefore as individual to us as a fingerprint. The most important tasks of the microflora in the intestine include breaking down indigestible substances, defending the body against pathogens and training the immune system.

In the womb

For a long time, it was thought that the intestine of an unborn child was sterile. However, it is not clear whether that is really the case, as scientists have made an astounding discovery: They have found the DNA of types of bacteria belonging to the mother's oral flora in the placenta of women who have just given birth – although the evidence does not reveal whether the bacteria are living or whether these are only fragments of bacteria. In any case, a mother's oral flora plays an important role in the health of her baby. If the oral flora has a poor composition, as is the case in those suffering from periodontitis, the risk of premature birth increases.

During birth

It is the type of birth that primarily determines the child's bacterial colonisation. During a natural birth, the baby first comes into contact with the mother's vaginal flora, and then later also with the mother's skin bacteria. In a Caesarean section, the baby does not have this contact with the mother's vaginal flora. The mother's skin bacteria and the bacteria from the hospital environment therefore colonise the baby's intestine. Lactic acid bacteria, such as lactobacilli, as well as Bifidobacteria and types of Bacteroides are amongst the first types of bacteria found in babies born in a vaginal delivery. Babies born by Caesarean do not get these bacteria until later. These children are also more prone to illnesses such as allergies and asthma.

The first few years

During the first few years of life, the bacteria from the mother's milk and the bacteria from the child's surrounding environment build up the intestinal flora. Whether a baby is breastfed or given commercially manufactured milk is reflected in the composition of the intestinal flora. The intestines of children who are breastfed are primarily colonised by lactic acid bacteria. They are particularly good at fending off pathogens. Bottle-fed children, on the other hand, have a similar intestinal flora to adults.

As numerous studies on bacterial colonisation conducted over the past decade have shown, the more varied the intestinal flora, the healthier it is. However, our modern lifestyle discourages this bacterial diversity. A natural birth, older brothers or sisters and a farm environment contribute to the diversity of bacteria – and are factors that are often missing in our modern society.

It is during these early years that the immune system learns, using the intestinal flora, to differentiate between what is harmful and what is harmless. If this bacterial diversity is restricted, the immune system cannot develop sufficient tolerance to harmless substances, just as it cannot build up enough strength to fight pathogens. This is why an intestinal flora which been adversely affected can be a contributing factor in the development of allergies, autoimmune diseases or even a weakened immune system.