If you suffer from chronic hives (urticaria) then you are desperate to find a cause. The one allergy that will fix your problem. Often foods, food additives or food preservatives are suspected. When you break out every day and eat multiple times in a day then there is bound to be some overlap. A few months ago, I looked at the evidence for diet changes as a treatment of chronic urticaria (link). There were only a small number of studies with little evidence for or against the role of food allergy in causing hives. A new study attempts to provide a more definitive answer.
The study, from Scripps Clinic in San Diego, California was designed to overcome two main obstacles. The first obstacle is bias. If a patient believes that a food is causing their hives this may result in higher stress, anxiety and more hives. A blinded study is needed to prevent bias. In the final arm of their study, neither patients nor investigators were aware if they were ingesting a food additive or a placebo (sugar pill). The second obstacle is the medication used for treatment. Symptoms are controlled with anti-histamines, if these medications are stopped for the study then the hives will naturally recur. This could result in a false positive. On the other hand, if the patient is on ‘too much’ anti-histamine then a reaction may be masked (a false negative). The author’s solution was to maintain patients on a minimum effective dose of medication.
After completion (ten years), one hundred patients had been challenged with 11 food additives, including:
- FD&C Yellow 5
- FD&C Yellow 6
- Potassium metabisulfite
- MSG 2500
- Sodium benzoate
- Methyl paraben
- Butylated hydroxyanisole
- Butylated hydroxytoluene
- Sodium nitrate
- Sodium nitrite
Although 43 patients reported a history of reaction to food or drug additive prior to the study, NO patients reacted to a double-blind challenge. The conclusion, sensitivity to food additives appears to be rare in patients with CIU, and avoidance is NOT recommended. One study is not proof, but this new information does makes food additives as a singular cause of chronic hives fairly unlikely. We must continue the search for the environmental, infectious and immunologic factors resulting in this burdensome disease.
Rajan JP, Simon RA, Bosso JV. Prevalence of sensitivity to food and drug additives in patients with chronic idiopathic urticaria. J Allergy Clin Immunol Pract. http://dx.doi.org/10.1016/j.jaip.2013.10.002.