Mireia Valles-Colomer

An opinion piece signed by researchers from the Universities of Aberdeen and Nottingham (UK) has outlined some of the inaccuracies, exaggerations and misconceptions they say are taking place around research on the human microbiome. Some of these are curiosities, like the false belief that we have ten bacteria for every human cell. Others are more relevant, such as the fact that many specific associations between the microbiome and disease have not been confirmed in follow-up studies. According to the authors, it is important to raise awareness about myths and misconceptions to avoid unproductive research projects and preserve public confidence in microbiome science. The article is published in the journal Nature Microbiology.

About 58.5% of a baby's microbiota come from various parts of its mother's body, according to a study of the transmission of microbes between mother and child in the first month of life. The research, published in Cell Host & Microbe, is based on samples collected from 120 mother-baby pairs, with material from their nose/throat, saliva, skin, milk, vagina and faeces. It compares babies born by caesarean section and vaginally, and confirms that the reduced transfer of faecal microbes in caesarean births can be partially compensated by other transmission routes, such as breastfeeding.

The establishment of the baby's microbiota occurs around the time of birth, when it receives bacteria directly from the mother. A study in the journal Cell suggests that genes can also be transmitted between them by horizontal transfer, without the need for the passage of these micro-organisms.