Common Bacteria Helps Treat Food Allergies
Promising Results in Animal Studies Offer Hope for Treatment in Humans
Nov. 12, 2004 - An experimental treatment for peanut, milk, and wheat allergies appears to have fared well in lab tests on dogs, markedly reducing the severe allergic response in these animals, say California researchers.
Experts from four universities -- Stanford University and the University of California at San Francisco, Davis, and Berkeley -- teamed up for the project.
The researchers included pediatrics professors Oscar Frick of UCSF and Dale Umetsu, MD, PhD, of Stanford. Their findings are reported in the Nov. 12 online edition of the journal Allergy.
Food allergies affect many Americans. Peanut and tree nut allergies affect about 1.5 million people in the U.S., and accidental ingestion by an allergic individual causes an estimated 150 deaths per year, write the researchers.
Many people are also allergic to milk, wheat, and other foods. "Allergy to all foods affects 6%-8% of children under age 4 and about 2% of the general population," the researchers write.
It can be tough to avoid such foods. It's not as simple as skipping peanut butter, dairy products, or bread, since ingredients based on peanuts, milk, and wheat are present in many processed foods.
The researchers tested the treatment, which is based on common food-borne bacteria called listeria. The heat-killed listeria plus a little bit of the offending food was given to the animals as allergy shots. This type of therapy is given to increase the body's tolerance to the substances (allergens) that provoke allergy symptoms.
The scientists treated two groups of dogs. The first group consisted of four dogs that were extremely allergic to peanuts; the second group was made up of five dogs that were very allergic to cow's milk, wheat, beef, and ragweed. All the dogs had had their food allergies for at least four years. The food allergy resulted in severe vomiting and diarrhea when the animals ate the foods they were allergic to.
The researchers injected the dogs once. The first group received shots of listeria plus peanut, while the second group received listeria plus milk and wheat.
Both groups showed marked improvement, with reduced reactions on skin tests for more than 10 weeks after the treatment was given. They also showed improved ability to tolerate the problem foods, with either minor or no stomach symptoms.
The vaccine allowed three dogs in the peanut group to tolerate the highest dose of ground peanut butter -- 20 grams -- without developing any symptoms. Before the vaccination, one of those three dogs had had the most severe reaction to just 0.2 grams of peanut.
The researchers say a similar strategy might "greatly improve" food allergy and anaphylaxis (severe and potentially fatal allergic reaction) in humans.