Gut Bacteria Protect Against A Common Food Allergy

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The gut microbiome plays a crucial role in protecting against food allergies, according to a new study.

There has been a startling rise in potentially life-threatening food allergies over the last 50 years. This rise has been linked to a range of potential culprits, including the misuse of antibiotics and changes in dietary habits.

Now, scientists have more concrete evidence that the gut microbiome plays a fundamental role in the development of food allergies and could be modified to prevent their development.

The study has recently been published in the journal Nature Medicine.

Scientists previously found that infants allergic to cow’s milk had different types of gut bacteria to infants without allergies.

Research also showed that some bacteria are associated with lower risk of food allergy – leading scientists to ask whether gut microbes in children without allergies might be protective.

To investigate this hypothesis, scientists at the University of Chicago took fecal samples containing gut microbes from eight human babies. Four of the infants had cow's milk allergy, while the other four did not.

The researchers then transplanted gut bacteria from each of eight infants into groups of mice raised in a germ-free environment and sensitized to milk protein—meaning the animals’ immune systems created allergic antibodies to milk.

The scientists then gave milk to the mice.

Mice that received no bacteria or bacteria from allergic children experienced anaphylaxis, which is a potentially life-threatening allergic reaction.

Mice receiving gut bacteria from non-allergic infants had no reactions.

The investigators then compared the gut bacteria of the allergic germ-free mice with those that showed no allergic reaction.

The comparison revealed the presence of a particular bacterium, called Anaerostipes caccae, which seems to prevent allergic reactions to food.

Anaerostipes caccae belongs to a family of bacteria called Clostridia, and previous work has shown that the presence of these bacteria in the gut protects against nut allergy.

So, it seems that this protection extends to other types of food allergy.

Anaerostipes caccae produces a short-chain fatty acid called butyrate. This nutrient helps the gut to establish a bacterial composition that promotes health.

The researchers were surprised by big of an impact this one species of bacteria can have on the body’s reaction to food. And the race is now on to figure out how to use this information to prevent children from developing food allergies.

Reference:

Feehley, T., Plunkett, C. H., Bao, R., Hong, S. M. C., Culleen, E., Belda-Ferre, P., ... & Andrade, J. (2019). Healthy infants harbor intestinal bacteria that protect against food allergy. Nature Medicine, 1.