The Peanut Paradox: How Overprotection May be Making Allergies Worse

Over the past decade, rates of peanut allergies in the Western world have doubled. Until recently, researchers and parents alike have struggled to understand why.

After all, around the year 2000, public health guidelines in the U.S. and the U.K. encouraged children to avoid allergenic foods. Accordingly, parents and schools became stricter than ever about keeping peanuts out of the kitchen and the classroom. Shouldn’t these changes have made everyone safer? 

A study performed in 2008 suggests precisely the opposite: allergies skyrocketed, and according to experts, our collective avoidance of peanuts might be to blame [1].  

Correlation Between Early Exposure and Allergy Rates 

The study in question compared rates of peanut allergies in Jewish children in the U.K. and in Israel and found that allergy rates were 10-fold higher in the U.K. What was the major difference between the two groups? It wasn’t genetics, or social class – both potential culprits. It was simply the age at which infants were first exposed to peanuts, and the frequency of that exposure early in life.  

According to survey data, it turns out that Israeli children are exposed to peanuts very early on in infancy and continue to consume them in high quantities during their first year of life. Conversely, U.K. children are more often sheltered from peanuts early in life. The researchers inferred that early exposure may confer some sort of protective immunity. 

The concept of inoculation, of course, is nothing new: we've known for a very long time that when it comes to germs and the immune system, what doesn’t kill you makes you stronger. It's a simple idea: expose a person to a small amount of a pathogen, and the body will develop a tolerance to protect them from future exposure. Might this principle apply to non-infectious agents, such as food allergens?  

Experimental Research Confirms Survey Study 

This hypothesis was tested in 2015, in a randomized controlled trial of 640 infants (between four and eleven months old) who were specifically selected due to their propensity towards eczema and other allergies [2]. Researchers split the infants into two groups: an ‘exposure’ group, and an ‘avoidance group.’ The ‘exposure’ group was provided very small doses of peanut snacks on a weekly basis for the next five years. The other half avoided peanuts altogether.  

When the study came to a close, the results were staggering: the five-year-olds in the ‘exposure’ group were about 80% less likely to be allergic to peanuts. In absolute terms, that translates to 13.7% in the ‘avoidance’ group, versus 1.9% in the ‘exposure’ group.  

For those wondering, the intervention was safe; there were no deaths in the study, and the rates of serious adverse events were equal in both groups.  

Bottom Line 

As counterintuitive as it may seem, the increase in peanut allergies in the Western world may be a result of our society's attempt to make our kids safer. By embracing an approach of exposure to peanuts and other potential allergens, we may be able to prevent the development of allergies and – as some research is starting to suggest – even develop a tolerance in those who have already developed an allergy.  

References

[1] Du Toit, G., Katz, Y., Sasieni, P., Mesher, D., Maleki, S. J., Fisher, H. R., ... & Lack, G. (2008). Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy. Journal of Allergy and Clinical Immunology, 122(5), 984-991. 

[2] Du Toit, G., Roberts, G., Sayre, P. H., Bahnson, H. T., Radulovic, S., Santos, A. F., ... & Lack, G. (2015). Randomized trial of peanut consumption in infants at risk for peanut allergy. N Engl J Med, 372, 803-813.