27 July 2010

Food allergies: few good studies

There's a lack of consistent information about the prevalence, diagnosis and treatment of food allergies, according to researchers.


There's a lack of consistent information about the prevalence, diagnosis and treatment of food allergies, according to researchers who reviewed data from 72 studies.

The articles looked at allergies to cow's milk, hen's eggs, peanuts, tree nuts, fish and shellfish, which account for more than 50 percent of all food allergies.

The review authors found that food allergies affect between 1 percent and 10 percent of the U.S. population, but it's not clear whether the prevalence of food allergies is increasing.

While food challenges, skin-prick testing and blood-serum testing for IgE antibodies to specific foods (immunoglobulin E allergy testing) all have a role to play in diagnosing food allergies, no one test has sufficient ease of use or sensitivity or specificity to be recommended over other tests, Dr. Jennifer J. Schneider Chafen, of the VA Palo Alto Healthcare System and Stanford University School of Medicine, and colleagues, said in a news release.

Elimination diets are a mainstay of food allergy therapy, but the researchers identified only one randomized controlled trial (RCT) -- the gold-standard of evidence -- of an elimination diet.

"Many authorities would consider RCTs of elimination diets for serious life-threatening food allergy reactions unnecessary and unethical; however, it should be recognized that such studies are generally lacking for other potential food [allergy] conditions," the researchers wrote.

In addition, there's inadequate research on immunotherapy, the use of hydrolyzed formula to prevent cow's milk allergy in high-risk infants, or the use of probiotics (beneficial bacteria) in conjunction with breast-feeding or hypoallergenic formula to prevent food allergy, according to the report published in the May 12 issue of the Journal of the American Medical Association.

"This systematic review of food allergies found that the evidence on the prevalence, diagnosis, management and prevention of food allergies is voluminous, diffuse and critically limited by the lack of uniformity for the diagnosis of a food allergy, severely limiting conclusions about best practices for management and prevention," the researchers concluded. - (HealthDay News)

More information

The U.S. National Institute of Allergy and Infectious Diseases has more about food allergy.


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