How bacteria could help combat food allergies


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According to organization Food Allergy Research and Education (FARE), around 15 million Americans suffer with food allergies. And, while the number of food allergies cases continues to grow, there are still too few treatment options. The use of probiotics has shown some promise, however. Lactobacillus might sound familiar — it's the good kind of bacteria in "live" or "active" yogurt — but is only one of many types of bacteria that have potential health benefits. A new study shows that targeting specific areas of the gut could produce real relief for allergy sufferers.



In the United States, the number of children with food allergies increased by 18% between 1997 and 2007. During this same period allergy-related hospital visits tripled. Though some probiotics have proven very effective for reducing food allergies, this is not the case for all probiotic bacteria. However, the new study — conducted by the Institute for Basic Science (IBS) and the National Institute of Animal Science — shows that the introduction of the probiotic Bifidobacterium longum also has the ability to reduce the effects of food allergies.

The IBS team tested two strains of bacteria — Bifidobacterium longum and Enterococcus faecalis — on mice. The animals were later exposed to food allergens to see what effect these would have on their immune system response. Mice with an E. faecalis intestinal population did not show any change in allergic response. In mice with B. longum intestinal populations, however, there was a significant suppression and delay in the occurrence of diarrhea.



These probiotics work by releasing tiny spherical packets — known as extracellular vesicles (EVs) — into the small and large intestines. These EVs contain protein and DNA from the bacteria and their release affects the immune system. In the case of B. longum, they contain a protein known as ESBP that interacts with the mast cells in the intestines responsible for allergic reaction, killing them and, thus, neutralizing their ability to induce allergy. The researchers gave the mice a common test allergen containing albumin — the protein in egg whites — and looked for the signs of intestinal distress (in this case diarrhea), which would indicate an allergic response.

The team not only observed the influence of EVs on mast cells but also noted that dose was an important factor in controlling effectiveness. Less than 5 x 109 colony forming units (cfu) of bacteria per mouse per day, they say, was not enough to prevent allergic response from occurring. "Our study is the first to discover the probiotic strain's mechanism of controlling food allergies without affecting regulatory T cells," the team says. "Since mast cells are the root cause of all allergic reactions… ESBP protein might be used [in the] therapeutic treatment of other allergic diseases as well as food allergy." Other possible applications, for example, could include skin creams to treat eczema.