Food Allergies May Not Be As Common As We Think

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Main Category: Allergy
Also Included In: Nutrition / Diet
Article Date: 14 May 2010 - 0:00 PDT

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There are a limited number of good-quality studies on food allergies, with inadequate uniform criteria for making a diagnosis and establishing prevalence and effective treatment, says an article published in the Journal of the American Medical Association (JAMA), May 12^th issue.

Family eco¬nomics, social interactions, school and work attendance and health-related quality of life can be severely undermined by food allergies.

The authors of the article write "However, currently licensed treatments target only the symp¬toms of reactions and anaphylaxis [severe allergic reaction], not the allergies themselves."

Background information on the article claims there is no clear agreement regarding the prevalence or most effective diagnostic and management approaches to food allergies.

Jennifer J. Schneider Chafen, M.D., M.S., of the VA Palo Alto Healthcare System, Palo Alto, and Stanford University School of Medicine, Stanford, Calif., and team examined the available evi¬dence on the prevalence, diagnosis, man¬agement, and prevention of food aller¬gies. They identified 72 studies that met criteria. The studies had information on food allergies to cow's milk, hen's egg, pea¬nut, tree nut, fish, and shellfish - accounting for over 50% of all food allergies.

The researchers found that:

• Although elimination diets are the basis of therapy, they identified only 1 randomized controlled trial (RCT) 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 allergic conditions .."
• Among high-risk babies, hydrolyzed formula may prevent against cow's milk allergy, but standardized definitions of high risk and hydrolyzed formula do not exist. Probiotics combined with breastfeeding, hypoallergenic formula, or both may help stem food allergy, but their independent effects remain unclear.
• Food allergies affect over 1% or 2% but less than 10% of the American population. We are not even sure whether the prevalence of food allergies is rising.
• Food chal¬lenges, skin prick testing, and serum food-specific immunoglobulin E all have a role to play in making the diagnosis but no one test has suffi¬cient ease of use or sensitivity or speci¬ficity to be recommended over the other tests. Many other proposed diag¬nostic tests are of uncertain value due to lack of evidence.
• Immunotherapy, although currently not a licensed method for the treatment of food allergy, may be effec¬tive in generating desensitization, but whether this treatment can also gener¬ate long-term tolerance remains to be determined. The safety of immunotherapy is likely to vary with the food al-lergen and the route of therapy administration and, to date, has not been adequately studied.

The authors write "This systematic review of food aller¬gies found that the evidence on the prevalence, diagnosis, management, and prevention of food allergies is vo¬luminous, diffuse, and critically lim¬ited by the lack of uniformity for the diagnosis of a food allergy, severely lim¬iting conclusions about best practices for management and prevention."

"Diagnosing and Managing Common Food Allergies - A Systematic Review"
Jennifer J. Schneider Chafen, MD, MS; Sydne J. Newberry, PhD; Marc A. Riedl, MD; Dena M. Bravata, MD, MS; Margaret Maglione, MPP; Marika J. Suttorp, MS; Vandana Sundaram, MPH; Neil M. Paige, MD, MSHS; Ali Towfigh, MD; Benjamin J. Hulley, BS; Paul G. Shekelle, MD, PhD
JAMA. 2010;303[18]:1848-1856.

Edited by Christian Nordqvist
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