“Microbiome” is the term used to refer to the microorganisms present in a particular environment. The human body contains a number of microbiomes, such as the one found in our digestive systems. Research has shown that the microbiome that grows in the gut when we are children likely influences our health as adults.
The intestinal microbiome is formed immediately after birth. It is based in part on the microbes obtained from the birth canal and from breastfeeding. If a child is born via Caesarean section, the microbiome forms more slowly and differs from that of naturally delivered babies. A study is investigating whether babies born via Caesarean section should have their microbiome altered afterwards.
Both the genome and the childhood environment – such as the family’s characteristics and to some extent diet – play a role in the formation of the microbiome. It develops its unique profile during the child’s first years, much in the same way as fingerprints.
Disorders in the microbiome are associated with a variety of diseases, including allergies, asthma and rheumatoid arthritis. They also have links to childhood obesity and colic. Furthermore, antibiotics can cause long-term changes in the microbiome.
The characteristics of the best microbiome from a health perspective are not yet known. Therefore, the biome cannot currently be further optimised, and we do not know, for example, whether the condition of the microbiome can be improved by diet and, if so, by what kind. In addition, faecal microbiota transplants, which have been much talked about lately, have not been helpful so far, because it is not clear what exactly should be transferred.
The microbiome is closely linked to the hereditary immune system, and one affects the other. However, it is not known which one changes first when a person falls ill. New techniques, such as classifying bacterial genetic material, may help to determine further associations. The picture nevertheless remains complex, as in addition to bacteria, the microbiome is formed of viruses and fungi whose genes have not yet been mapped.
It is likely that the microbiome we receive as children plays a role on how healthy we are as adults. Among other things, it may affect the development of diabetes or inflammatory bowel diseases. It is therefore important to discover how the microbiome functions and whether it can be changed.
Kaija-Leena Kolho, professor of paediatrics at the University of Tampere, was interviewed for this story. She has studied children’s inflammatory bowel diseases (IBD) for many years. Among other things, she has been involved in drafting international treatment guidelines for the disease.
Text: Hanna Hyvärinen
Photograph: Jonne Renvall