Background
The microbial community living in the gut (gut microbiome) is a key player in human health and disease. During childhood, gut microbiome maturation happens alongside the development of human physiology. Disruptions the gut microbiome during childhood, when the body experiences maximal immune, metabolic, and neuroendocrine development, might give rise to various diseases.
The human gut microbiome is an active and emerging field of study and it is not yet known what comprises a healthy microbiome. The gut composition is influenced by lifestyle factors, social-economical status, and medical history (e.g., antibiotics use, recent infections). We hypothesise that the gut microbiome of healthy children is substantially different from children suffering from chronic diseases.
The most common technique for mapping gut microbiome composition is sequencing of DNA isolated from stool samples. To gain insights into the gut microbiome function, a state-of-the-art method is the determination of the faecal metabolome, i.e., the collection of small molecules present in faeces. A recent estimate suggested that gut bacterial products account for up to 90% of the faecal metabolome, reflecting the microbial composition and being a functional readout of the microbiome.
Cataloguing the gut microbial profiles in the healthy population is essential for clinical studies investigating the microbiome. The Norwegian children's population is relatively homogeneous regarding cultural and lifestyle factors (FHI public health report; Health Status in Norway 2018). Besides the geographical location, any microbiome study has to control factors that influence the microbiome, such the mode of birth, diet, living conditions (urban versus rural), presence of animals, medication use, older siblings, as well as the socio-economical status of the family. In this way, one can limit the confounding factors, which can dilute subsequent statistical analyses. Therefore, it is essential to record information about the subjects, samples, and experimental procedures in microbiome research. The collected information becomes part of "metadata" linked to de-identified samples and used to analyse the microbiome data.