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| Microbiome inside human stomach |
The microbes living in our gut could vary with the seasons, according to the evidence from a group of hunter-gatherers. Jeff Leach of the Human Food Project charity and his team spent more than a year collecting stool samples from 350 Hadza people, living in Tanzania. The team discovered that the Hadza microbiome is about 30 per cent more diverse than that of people in Western nations, and it seems to change in a cycle through the year.
Diversity peaks in the dry season, when Prevotella species increase. The bacteria that showed the greatest annual fluctuations generally tended to be strains not present in people with Western lifestyles (Science,DOI:10.1126/science.aan4834). These annual changes in the gut microbiome are probably caused by cyclical shifts in the Hadza diet. During Tanzania’s dry season, the Hadza people eat a lot of meat plus tubers and fruit from the baobab tree, but in the wet season they eat more honey and berries.
This is the first detection of an annual cycle of microbiome changes, says Willem de Vos of Wageningen University in the Netherlands. He predicts that microbiomes may also cycle in those of us who manage to eat seasonal produce.