Few high-quality food allergy studies available
May 14, 2010
by Erica Shaffer
PALO ALTO, CALIF. — A review of previous research revealed few high-quality studies on food allergies are available, with limited uniform criteria on making a diagnosis and determining prevalence and effective treatments, according to an article in the May 12 issue of the Journal of the American Medical Association.
Jennifer J. Schneider Chafen of the VA Palo Alto Healthcare System and Stanford University School of Medicine, Stanford, Calif., and colleagues reviewed the available research on prevalence, diagnosis, management and prevention of food allergies. They found no clear consensus regarding the prevalence or most effective diagnostic and management of food allergies.
“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 authors said.
The studies covered available data on food allergies to cow’s milk, hen’s egg, peanut, tree nut, fish and shellfish, which account for more than 50% of all allergies to food. The researchers found:
• Food allergies affect more than 1% or 2% but less and 10% of the U.S. population, meaning the prevalence of food allergies is not well established.
• Diagnostic tests such as food challenges, skin prick testing and serum food-specific immunoglobin E all have a role to play, but no one test has “sufficient ease of use or sensitivity or specificity to be recommended over the other tests,” according to the researchers. Also, numerous other tests are of uncertain value due to lack of evidence.
• Researchers found only one randomized controlled trial (RCT) of an elimination diet, although elimination diets are the most common therapy for food allergies. “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 allergic conditions…” the authors wrote.
• Immunotherapy may be effective in producing desensitization, but is currently not a licensed treatment for food allergies. Safety of immunotherapy is likely to vary among food allergens and the route of therapy administration, but so far has not been adequately studied.
• Among high-risk infants, hydrolyzed formula may prevent against cow’s milk allergy. But standardized definitions of high risk and hydrolyzed formula do not exist. Probiotics in conjunction with breastfeeding, hypoallergenic formula or both may help prevent food allergy, but their independent effects remain unclear.