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New study hints at probiotic use for food allergies

Posted:  Friday, September 12, 2014

Bacteria in the gut can help protect mice against peanut food allergies, according to a new study. The findings suggest that probiotics might help treat or prevent these potentially lethal food allergies in people, researchers say.

In a striking new finding, probiotic Clostridia in the gut may protect well against food allergies.

The study, published in the Proceedings of the National Academy of Sciences, found that germ free and antibiotic treated mice exposed to peanut allergens displayed aggravated immune response in comparison to mice with normal gut bacteria. However, this adverse reaction was reduced specifically when Clostridia colonies were reintroduced in germ free mice.

According to the team of researchers, Clostridia helps in reducing the intestinal wall permeability by modulating innate immune cells to secrete interleukin-12 (IL-12). Because of this crucial step, the allergen is restricted from entering the bloodstream and immune sensitization is prevented.

In other words, it helps prevent leaky gut syndrome—a condition that allows allergens to enter your bloodstream, thereby producing an immune response. The researchers suggest this discovery may eventually lead to probiotic therapies to treat food allergies.

“It's exciting because we know what the bacteria are; we have a way to intervene. Probiotic bacteria as a therapeutic agent is absolutely testable against food allergies for which there is no treatment”, said senior study author Dr. Cathryn Nagler, University of Chicago.

Clostridia are a highly diverse class of bacteria, and are also common in humans. There are toxic Clostridia, such as Clostridium difficile, but the types of Clostridia used in the new study did not include the toxic kind, Nagler said.

Although the causes of food allergies – and the reason they have become more predominant in recent years – remain unknown, there are many theories. One leading theory is that modern hygiene, diet and use of antibiotics and antimicrobials act to disturb the body's natural bacterial composition.

Previous studies have suggested that modern changes in diet, hygiene and the increased use of antimicrobials might disturb the body's microbiota, the population of bacteria that naturally live in and on people. This change, in turn, might increase people's susceptibility to food allergies, researchers say.

Prevalence of food allergy among children has risen sharply, by 50% between 1997 and 2011. Studies have clearly highlighted antibiotic and antimicrobial use as the reason for this jump. Apart from these, food allergies have largely complex and unknown factors making it difficult to treat. Since Clostridia are a common class of gut bacteria, treatment targeting them might be easier.

Other recent findings have made it increasingly clear that gut microbes have many important functions within the body. For instance, they help make some essential vitamins and break down otherwise indigestible dietary fiber. They also release signals that help the immune system function.

Although these study findings need to be documented by large scale epidemiological studies, the possibility of preventing food allergies by simply altering the gut micro-flora is definitely a way forward.

Nutrition in DiarrheaDr. Rahul Verma MD DCH MRCP (UK) 1