Researchers analyzed three publicly available gut-microbiome datasets that together cover 24 populations across four continents. The samples ranged from hunter-gatherers and pastoralists in Botswana, Tanzania and Nepal to rural farmers in Malawi and Venezuela and urban residents in Philadelphia and St. Louis. One dataset included information on breastfed and formula-fed infants.
Earlier work shows that inactive estrogen is excreted into the intestine, where microbes break it down. A large share of this discarded estrogen can then be reactivated by microbes and reabsorbed into the bloodstream. The new study focused on the estrobolome, the subset of gut microbes involved in that process.
The researchers report that microbiomes in industrialized populations have up to seven times greater capacity to recycle discarded estrogen than those in non-industrial populations. They also found that formula-fed infants have two-to-three times the recycling capacity of breastfed infants. Composition differences were clearer too: the estrobolome was much more diverse in formula-fed infants and in industrialized groups. One researcher said this surprise contrasts with the usual finding that overall gut diversity is lower in industrial societies.
The lead author said daily environments, diets and habits in industrialized society may shape these microbes. Other experts noted diet, activity, sanitation and health care access could all play roles. A new project funded by the Polish National Science Foundation will study these questions further, and the study appears in Proceedings of the National Academy of Sciences.
Difficult words
- microbiome — Community of microbes living in a body areagut-microbiome
- estrobolome — Part of gut microbes that affects estrogen recycling
- estrogen — A hormone that affects body development and reproduction
- capacity — Ability or power to do a specific action
- formula-fed — Given commercial infant milk instead of breast milk
- diversity — Variety of different species or types present
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Discussion questions
- Why might daily environments, diets and habits in industrialized societies change the estrobolome?
- How could the higher recycling capacity in formula-fed infants affect health later in life?
- What kinds of follow-up studies would help show how sanitation or diet affect these gut microbes?
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