04 July 2022
Lifestyle influences infant microbiome development
Published online 16 June 2022
Children from the Hadza hunter-gatherer tribes in Tanzania have a more diverse gut microbial composition than those living in industrialized regions, highlighting the importance of expanding studies to different populations.
Many studies of the developing gut have examined infants solely from wealthy, industrialized nations, and therefore little is known about infant microbiome assembly in non-industrialised or nomadic peoples.
In a unique genome sequencing study comparing infants from industrialized regions with infants from the Hadza hunter-gatherer tribes in Tanzania, Justin Sonnenburg at Stanford University, California, together with scientists including Aashish Jha at New York University Abu Dhabi, UAE, have demonstrated that lifestyle is the leading influence on infant microbiome development and composition. Further, 23% of the 745 gut microbial species found in Hadza infants have not been documented, highlighting significant variations in human gut development across populations.
The microbiome composition in adults and infants from industrialized nations tends to have low diversity, while adults from non-industrialized regions have more complex, diverse microbiota. The composition of the gut microbiome directly influences health in adulthood.
The researchers sequenced 62 stool samples from Hadza infants, together with samples from the mothers of 23 of the infants. Hadza infants are brought up in a semi-nomadic, small community environment, and are weaned from breastmilk at around two years old.
The team compared the Hadza results with data from infants and mother-infant pairs in industrialized nations. All infants begin life with Bifidobacteria-dominated gut microbiome, regardless of lifestyle. More specifically, Hadza infant guts were dominated by Bifidobacterium infantis, which utilizes components of human breastmilk efficiently. Industrialized infants had less B. infantis and more B. breve, a species far less reliant on breastmilk.
By six months, however, the microbiomes of industrialized infants had diverged considerably from their non-industrialized counterparts, with different microbial co-abundance groups (CAGs) dominating. In infants from industrialized nations, more microbial species were lost than gained.
In mother-infant pairs, microbial species that were abundant in mothers were more likely to be shared with their babies. More specifically, the CAGs that become dominant after the first six months of life were most likely to be shared from mother to child. The team suggest that this long-term vertical transmission within populations could predispose those in industrialized nations to certain diseases, although this question requires further in-depth investigation. The researchers also highlight the importance of studying microbiomes from a wide variety of populations in future.
Olm, M. R. et al. Robust variation in infant gut microbiome assembly across a spectrum of lifestyles. Science 376, 6598 (2022).