Modern-day allergists seem to be taking a cue from the history books: ancient kings supposedly intentionally ingested poisons to build up their tolerance to toxins in case of a murder attempt. This week, researchers report that people suffering from peanut allergies may build up their tolerance to peanuts in a similar way — by eating extremely low doses of the allergen.
For the new study, published in the Journal of Allergy and Clinical Immunology, 40 adolescents and adults with the food allergy were tested for the maximum amount of peanuts that would generate an allergic reaction tolerance. Then, half of them took minuscule quantities of peanut powder under their tongue daily, with the doses increasing gradually every day. The other half were given a placebo powder.
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After 44 weeks, 14 of the 20 who received the daily peanut powder could tolerate at least 10 times as much peanut as they could handle at the beginning of the study (or 5 grams in total, whichever was more), while only three of the 20 on placebo could do the same. Many of the people receiving treatment saw a 100-fold or better increases in their peanut tolerance. After the first stage of the experiment was finished, the group getting placebo was offered the chance to receive the peanut treatment too. Among that group as well, most were also able to improve their resistance to peanuts over subsequent months.
That doesn’t mean that those allergic to peanuts can try a similar strategy for building up their tolerance at home. In the experiment, even allergy sufferers who responded well could only handle a couple grams of peanut – a fraction of an ounce – after many months of training. The initial, first-stage training doses, in contrast, were far lower still, and much smaller than anyone could prepare in a home kitchen: mere billionths of a gram per day.
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“While promising, the treatment is not ready yet to try in physicians’ offices, or to do at home,” says Wesley Burks, professor and department chair of pediatrics at the University of North Carolina, and one of the primary researchers on the new study. “But we do have promise that it’s safe, that it works,” he says.
Burks, one of the leading researchers testing such a tolerance strategy for treating food allergies, says that a much larger study, with many more participants, is needed before doctors can be comfortable prescribing the treatment to everyday allergy sufferers.
In the study, for example, while most patients responded with only mild side effects such as an itchy mouth, one participant who received the peanut powder had a more severe reaction that required an EpiPen. A larger study would provide a better sense of how common such potentially dangerous reactions are.
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Testing the therapy in more people would also provide more accurate information about how effective the tolerance to peanuts might be in the real world. In the current study, for instance, many patients developed a strong enough resistance to peanuts that they could potentially tolerate, with few symptoms, some trace exposure to peanuts such as might occur by eating something produced with kitchen implements that touched the nuts. But it’s not clear whether that benefit persists once the daily peanut dosing stops. And none of the patients were cured of their allergy to the point that they could eat, say, a peanut butter and jelly sandwich or anything like it.
Still, the findings are exciting because there are currently no good treatments for food allergies – and peanuts and other tree nuts are among the most common food triggers of life-threatening allergic reactions. Burks says the idea of building up a tolerance to allergens may be applicable to a host of other food allergies as well. He and his colleagues have already conducted similar research with eggs, and found that eating tiny quantities of that dairy product may also help people with egg allergy to build up an immunity to allergic reactions.
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That’s good news for food allergy sufferers, particularly young children who might be accidentally exposed to their allergen. Many of them might someday be able to tolerate some exposure to the food that causes them problems, with limited symptoms. “There is work going on that is promising to develop a treatment for this disease,” Burks says.