How much peanut does it take to trigger an allergic reaction?

For individuals with severe peanut allergies, food-induced anaphylaxis can occur. It’s a life-threatening emergency that requires treatment with an injection of epinephrine and a trip to the emergency room. Food labels offer warnings such as “may contain peanuts”  or  “was processed in a facility that may process nuts.”  

The warnings allow individuals with severe reactions to steer clear, but for consumers who may be able to tolerate a minimal amount of peanut protein without major incident the labels aren’t very useful, says Lynne Haber, PhD, a University of Cincinnati College of Medicine senior toxicologist.

But a new study that Haber has led may help change that situation in the United States.

Using patient data from multiple locations, scientists used mathematical models to estimate an “eliciting dose” — or the amount of peanut protein that will cause or elicit an allergic reaction in a certain percentage of peanut sensitive patients, explains Haber. The study reviewed the responses of 481 patients in double-blind placebo-controlled studies, who were exposed to increasing levels of peanut protein in a controlled clinical setting until the patient had an allergic reaction.

The dose calculated to elicit an allergic reaction in 1% of patients with peanut allergies was 0.052 milligrams of peanut protein, about the weight of a single grain of salt, says Haber. The eliciting dose for 5% of patients was calculated to be 0.49 milligrams of peanut protein, or about the weight of a single grain of sugar, says Haber.

The findings were published in the scholarly journal Food and Chemical Toxicology.

“Risk is based on a combination of how inherently hazardous something is, and how much of that substance someone is exposed to,” says Haber, an adjunct associate professor of environmental and public health sciences in the UC College of Medicine. “Arsenic is more toxic than sodium chloride, also known as table salt, but if you’re not exposed to any arsenic, it does not pose any risk.”

“The amount of exposure is also important in determining risk,” says Haber. “Water is healthy, but if you drink enough of it, it could kill you. There has been a move to shift to labeling that is based on a combination of the inherent hazard of a substance and how much of it is in a product. This is being done in Australia, New Zealand and Europe. The United States has been slower to do this.”

Haber worked with patient data from Stanford Medicine and the Consortium for Food Allergy Research. The study was supported by The Institute for the Advancement of Food and Nutrition Sciences (IAFNS). This non-profit 501(c)(3) scientific research organization pools funding from food industry collaborators and advances science through the in-kind and financial contributions from public and private sector participants.

“We were asked to do analysis using data from the U.S. population as there may be differences between the U.S. and other countries in terms of peanut consumption and exposure that affect the sensitivity to peanut,” says Haber. “We have posted all the data and modeling code via the internet to ensure transparency. We have identified an exposure limit that is relevant to the U.S. population using a method and data that others can use for their own analysis.”

Other collaborators on the study were John Reichard, PhD, PharmD, assistant professor, and Melissa Vincent, a former research associate, both in the UC College of Medicine. Additional collaborators include independent consultant Bruce Allen, and Alice Henning and Peter Dawson, both of the Emmes Company, Rockville, Maryland; along with Sharon Chinthrajah, MD, Sayantani B. Sindher, MD, Andrew Long, PharmD, and Kari Nadeau, MD, all from Stanford Medicine. 

Funding for the contributions of Haber, Reichard, Henning, Dawson, Vincent and Allen was provided by IAFNS through an ILSI North America Food and Chemical Safety Committee grant.

Disclosures: Haber reports a recent contract with Specialised Nutrition Europe (SNE) (another organization with food-related interests) and the Flavor and Extract Manufacturers Association (FEMA), and is a subcontractor on a separate IAFNS project related to food risk assessment. Chinthrajah reports grants from NIAID, CoFAR, Aimmune, DBV Technologies, Astellas and Regeneron. Chinthrajah is also an advisory member for Alladapt, Genentech, Novartis and receives personal fees from Before Brands. 

Sindher receives grant support from the National Institutes of Health. Sindher is involved in clinical trials with Regeneron, Aimmune Therapeutics, DBV Technologies, Adare Pharmaceuticals, Sanofi and Novartis.

Nadeau reports grants from National Institute of Allergy and Infectious Diseases, National Heart, Lung, and Blood Institute (NHLBI) and National Institute of Environmental Health Sciences; Food Allergy Research & Education (FARE), director of World Allergy Organization Center of Excellence at Stanford; adviser at Cour Pharma; co-founder of Before Brands, Alladapt, Latitude and IgGenix; National Scientific Committee member at Immune Tolerance Network and National Institutes of Health (NIH) clinical research centers. Nadeau is a data safety monitoring board member for NHLBI and holds U.S. patents for basophil testing, multifood immunotherapy and prevention, monoclonal antibody from plasmablasts and device for diagnostics.

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