Donal Wall, Reader in Infectious Diseases at the University of Glasgow, gave a fascinating talk on the Human Microbiome – the multiplicity of micro-organisms living in and on our bodies, which have a profound impact on our health and wellbeing. Donal explained that more organisms live in and on us than we have cells, and that the number of genes in all the microbes in one person’s microbiome is 200 times the number of genes in the human genome.
Donal’s talk focused mainly on the gut microbiome although he touched on other areas such as the microbes on our skin and in our mouths. He noted that the gut microbiome has important effects in relation to: energy extraction from food; promoting gut integrity; educating the immune system to recognise pathogens; and limiting pathogen colonisation.
Donal explained that a new-born baby starts life sterile, but quickly gains helpful microbes via the mother’s birth canal. But babies born by caesarean section lack this beneficial start to life. Many factors also influence how the microbiome develops. As well as birth, antibiotics, diet, lifestyle and medication can all dramatically change the gut microbiome. But, by the age of 2-3 years, it is more or less stable. Western style diet and lifestyle have had a very significant effect in reducing the diversity of the microbiome. The use of antibiotics is also linked to disruption of the microbiome, allowing pathogens such as C Difficile to take hold causing severe diarrhoea. Antibiotic use in childhood is also strongly related to the development of inflammatory bowel disease. Donal noted that excessive hygiene in childhood can have a negative effect on the developing microbiome by limiting exposure to beneficial microbes and preventing the immune system from learning to recognise pathogens.
Among the many aspects of the microbiome covered in Donal’s wide-ranging talk were in relation to obesity and the gut brain axis. Regarding obesity he described animal studies in which obesity in mice could be manipulated by means of faecal transplantation from other thin or fat mice. Although the mechanism is not yet fully understood he noted that this research also has the potential to impact on obesity and type 2 diabetes in humans.
Regarding the gut-brain axis Donal noted that the gut microbiome has profound effects on the brain via secretion of chemicals which act in a similar way to neurotransmitters. It is suggested that these can impact on mental health conditions such as depression and anxiety. And there is also some interesting research in relation to autistic spectrum disorders.
Donal’s talk was very well received and there was a wide-ranging Q and A session including questions about the use of probiotic food and supplements and personalised nutrition.
Donal recommended a book by Ed Yong: “I Contain Multitudes: The Microbes Within Us and a Grander View of Life”. Below is also a YouTube link to Ed Yong’s Royal Institution lecture on this book.