Food Processing and Food Allergies

How Cooking Methods Affect Peanut Allergies

Boiled peanuts
Boiling peanuts may reduce the chance of peanut allergy developing.. Amar Lungare/Moment Open/Getty Images

Peanut Allergy: A Common Problem in Westernized Countries

Food allergies are becoming increasingly common in the United States (U.S.), particularly in children. And the rate of peanut allergy in particular has doubled in the U.S. and other Westernized countries over the last 10 years, now affecting one to two percent of the population. Severe, life-threatening allergic reactions to peanuts are common in people with peanut allergy, and have resulted in dozens of deaths in the United States and the United Kingdom (U.K.) over the past 15 years.
In other parts of the world, such as in Korea, China and Israel, the rate of peanut allergy is much lower than that of Westernized countries, for reasons that are not completely understood.

It is not clear why other countries in the world have lower rates of peanut allergy than in the U.S., but it's thought that the type of food processing method used might play a major role. In the U.S. and U.K., peanuts are generally dry roasted, while in other countries peanuts are more commonly boiled, fried or even pickled. A recent study looked at how processing peanuts changed how people with peanut allergy reacted to them — or rather, how IgE antibodies in a blood sample reacted to peanut allergens in a blood test for allergies.

How Processing and Cooking Changes Peanut Allergy

There are 3 major peanut allergens that have been described, called Ara h 1, Ara h 2 and Ara h 3. People living in the U.S. with peanut allergy most commonly are allergic to Ara h 2, especially those people with the more severe forms of peanut allergy.
It appears that the major peanut allergens are altered by how peanuts are processed when compared to raw peanuts. Roasting peanuts enhances how IgE antibodies react to Ara h 2, which could explain why people in the U.S. and U.K. tend to have more common and more severe allergic reactions to peanuts.
Boiling or frying did not significantly change Ara h 2 when compared to the amount found in raw peanuts. Pickling peanuts, on the other hand, completely stopped the ability of IgE antibodies to react to Ara h 2 in people with peanut allergy.

In Westernized countries, IgE to Ara h 2 is seen in more than 70% of people with peanut allergy; peanut allergic people in Korea were found to more commonly have IgE to Ara h 1 and Ara h 3. This difference in the pattern of allergy is likely caused by how peanuts are processed differently around the world. Peanuts are most commonly dry roasted in Westernized countries, which increases the ability of Ara h 2 to be an allergen. On the other hand, roasted peanuts are rarely eaten in Korea, where it is more common to eat pickled, boiled or fried peanuts, which seems to reduce the ability of Ara h 2 to act as an allergen. For this reason, it's likely that peanut allergy, especially severe forms, tend to be more common in Westernized countries compared to Asian countries.

Could Food Processing Be the Mystery Behind the Rise in Food Allergies?

If how peanuts are processed affects the ability of the food to result in a food allergy, it begs the question: does eating processed foods in general influence the chance of developing food allergies? Since we as a society frequently eat more processed foods and fewer "raw" (unprocessed) foods, this could be one explanation as to why there has been an increase in the rate of food allergies over the past few decades. Food processing could change the characteristic of the food allergen, making it more likely to cause symptoms of food allergy. We may find that certain types of processing cause more allergies, while other processing methods don't affect the risk of food allergy — or even reduce the chance of developing food allergies.

Pickled peanuts, anyone?


Kim J, Lee JY, Han Y, Ahn K. Significance of Ara h2 in Clinical Reactivity and Effect of Cooking Methods on Allergenicity. Ann Allergy Asthma Immunol. 2013;110:34-8.

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