The big (biome) buzz of the last couple of weeks: research just published out of Australia shows that the presence of a certain species of gut bacteria, Prevotella copri, in pregnant women protects babies from developing food allergies – at least within their first year.[i]
I have mentioned Prevotella bacteria in many posts over the last couple of months (for example, here and here). As a fermenter of fiber, it is present at higher levels in those who eat a plant-based diet…and thus, is found at lower levels in those who consume a typical “western” type diet, high in fat and sugar. It’s found at higher levels in the guts of most people living in ‘traditional communities”; and is non-existent or at very low levels in the vast minority of people living in developed nations. (Australia, by the way, has the highest rates of food allergy in the world.) The maternal microbiome has been shown in rodents to influence the rate of allergy in pups, particularly low levels of Prevotella.[ii]
In fermenting fiber, Prevotella increases levels of those short-chain fatty acids I write about all the time. In proper amounts, these are highly anti-inflammatory and play a big role in boosting levels of regulatory cytokines (which modulate inflammation). These scientists hypothesized that, “…it is plausible that low maternal carriage of Prevotella during pregnancy may be causally related to dysregulated immune development and high rates of allergic disease among children in westernized populations.”
The researchers analyzed data collected between 2010 and 2015 which looked at fecal samples from mothers at 36 weeks of pregnancy and then from their babies, at 1, 6 and 12 months of age. Children who had developed food allergy (58 in the cohort) were compared to those without (258 in the cohort).
They found that 20% of the babies that did not develop allergies had P.copri in their stool samples versus only 8% of babies with allergies: the presence of P.copri in the mom’s stool sample meant less risk of developing allergy for their baby. Only 1 mother with higher levels of the bacteria in her stool had a baby diagnosed with food allergy. Doubling the amount of P.copri in the stool meant an 8% drop in risk for the baby: “…maternal carriage of Prevotella copri during pregnancy strongly predicts the absence of food allergy in the offspring.” Remarkably, over 80% of the mothers in the whole database (over 1000 women) had no detectible P.copri in their stools.
While diet is the biggest factor in determining the composition of the gut bacteria, other environmental factors also play a role including antibiotic use and household size: as David Strachan, the father of the “hygiene hypothesis” predicted in 1989, more people in the house are thought to increase bacterial diversity within the family.
These scientists are now working to figure out whether or not it is safe to administer P.corpi as a probiotic during pregnancy to protect babies. Like everything having to do with the human biome, this is NOT a cut and dried kind of thing. The authors point out that 1 study has shown an association between P.copri and rheumatoid arthritis and another, in animals, showed that it may exacerbate colitis. Much of this may be dependent on the particular strain of the bacteria used. (Nothing is ever easy.) We’ll find out, I’m sure, as the research progresses.
This is pretty important work though as their findings would suggest that the absence of P.copri in the mother raises the risk of developing food allergy in the baby by more than 50%. That is just a remarkable finding.
I’ll conclude this post as they conclude their paper, as it sums up what we can do now perfectly: “In the meantime, our findings support the importance of antibiotic stewardship during pregnancy as well as a diet that optimizes the health of the maternal gut microbiome.”
[i] Vuillermin, P. et al. Maternal Carriage of Prevotella During Pregnancy Associates with Protection Against Food Allergy in the Offspring. Nature Community. 2020;11:1452. https://www.nature.com/articles/s41467-020-14552-1