Peanut Allergies: Research Links Early Exposure to Outcomes

peanut allergies exposure science dual allergen exposure hypothesis

Peanut allergies have mystified scientists and physicians for many years: what causes them, how can they be prevented, how can they be reliably diagnosed, and how can they be treated?

A new study (May 2020) published in the journal Pediatrics combines decades of research with new advances to highlight some general patterns and theories, bringing us one step closer to answering some of these questions.

The authors of the paper include scientists and pediatricians from the University of Manitoba, University of British Columbia, and the Icahn School of Medicine at Mount Sinai (in NY).

Below are some of their primary findings. Before following any of this published guidance, always speak with your child's pediatrician first to assess your baby's risk and get clear, concrete guidance:

  • Peanut Allergy Development: Overall Patterns
    • About 82% of peanut allergies appear to be inherited from parents.
    • Girls are generally less likely to develop peanut allergies than boys.
    • Vitamin D deficiency might increase the odds of developing peanut allergies.
    • Increased hygiene is sometimes associated with increased peanut allergy development.
    • New finding: Early skin exposure to peanuts in children with eczema or atopic dermatitis may increase the risk of peanut allergy development.
    • New finding: Early exposure to eating or drinking products containing peanuts may decrease the risk of peanut allergy development.
    • In contrast, avoiding peanut ingestion early in life (for example if you have a sibling with a peanut allergy) appears to be linked to higher rates of peanut allergy development.
    • The differences in outcomes due to skin exposure versus ingestion is called the dual-allergen hypothesis.
  • Peanut Allergy Prevention: Overall Patterns
    • Early oral exposure to products containing peanuts (first year of life) seems to reduce peanut allergy development.
    • Early oral exposure even during the first months of life (months 4 to 11) seems to reduce peanut allergy development.
    • These patterns appear to be true even for infants who show a positive result on a peanut skin prick test.
    • These findings are strong enough to lead the U.S. National Institute of Allergy and Infection Diseases to recommend infants consume products containing peanuts (especially for kids with eczema and/or egg allergies).
    • However, no clear guidance is provided about the amount or frequency of peanut ingestion needed to reduce peanut allergy development. 
  • Peanut Allergy Diagnosis: Overall Patterns
    • Many allergic reactions in babies and toddlers are attributed wrongly to peanut exposure.
    • Peanut allergy testing is commonly done with a skin prick test or blood plasma test (for peanut-specific IgE antibodies).
    • Current peanut allergy testing is not highly reliable, specific, or predictive of future allergic reactions.
    • The current gold standard diagnosis is called a peanut oral food challenge, which involves eating incrementally larger amounts of peanut products under a physician's close supervision. This is dangerous and carries high risks.
    • New improved blood tests are being developed that are more reliable and safer than the oral food challenge.
    • Major medical organizations agree that the immunoglobulin G testing for peanut sensitivity is not an effective diagnostic method.
  • Peanut Allergy Treatment: Overall Patterns
    • Peanut bans in schools and public spaces are controversial, and have generally not reduced risks to children with peanut related allergies.
    • Peanut-free tables for children with severe allergies have reduced epinephrine administration rates at school, which is a good sign that they are effective.
    • Schools are generally not trained or prepared to treat severe allergic reactions.
    • Labels on food products such as "May Contain Peanuts" or "Manufactured in a Facility that also Processes Peanuts" are not regulated, and there is no relationship between the amount of peanut in a product and the label used.
    • Antihistamines are a first-line of defense, but are not life-saving and only treat skin-related symptoms (rash). Epinephrine is the only life-saving treatment for severe peanut-related allergic reactions.
    • Risk of death due to anaphylaxis is very rare, in fact it is as rare as being struck by lightening (about 1 in 10 million).
    • Children with peanut allergies suffer higher anxiety and decreased quality of life relative to their non-allergic peers.
    • Sensitivity to peanuts varies widely across individuals, with some showing only sensitivity to high doses and others showing sensitivity to very small doses.
  • New Therapies for Peanut Allergy Treatment
    • Immunotherapy for peanut allergies usually involves incrementally increasing peanut oral ingestion, closely monitored by your physician.
      • This method has a lot of adverse events, especially gastrointestinal effects.
      • This method seems to be about 67-92% effective at reducing allergic responses to peanut products.
    • New methods are being developed and tested involving the same incremental administration, but with skin patches instead of ingestion.
      • This method is very new and not well tested, but it seems to be less effective than the oral ingestion method.

Some of these findings are relatively old, and some are new and exciting, opening the door for future therapies and treatments that can help prevent and diminish peanut-related allergies.

There are many limitations of research in this domain, and also several controversies in the science. These include different theories about mechanisms underlying peanut allergies, different opinions about how seriously to treat peanut allergies, and the effectiveness of different diagnostic and treatment methods.

Overall Conclusions for Parents

It's always difficult to take scientific findings from the literature and apply them to your parenting or lifestyle. Good research takes a long time to execute, and often some initial suggestions about prevention, diagnosis, or treatment end up being just plain wrong. So always take new findings with a grain of salt and seek guidance from a medical professional before implementing them with yourself or a child.

The best advice is to talk to your pediatrician about your child's specific risks, needs, and potential challenges. Never try to intentionally introduce peanut-containing products at a young age without first speaking to your child's pediatrician.

That being said, here are some of the main take-away points from this research.

Oral exposure to peanut-containing products during infancy (e.g., 4-11 months of age) might reduce the likelihood of developing peanut-related allergies.
If your child has eczema or any other dermatological issues, early skin exposure to peanut-containing products might increase the likelihood of developing peanut-related allergies.
Skin prick and blood tests exist for diagnosing peanut sensitivity, but they are very limited and not a good estimate of the severity of a future reaction.
Peanut-related food labels are not regulated and cannot always be trusted, as they do not indicate the amount of peanut products possibly in the food.
Peanut-free facilities do not always reduce the likelihood of allergic reactions occurring in the space, but peanut-free tables at school do appear to be effective.
Oral peanut therapies do appear generally effective for reducing the severity of peanut-related allergies, but also have many side effects.

References

Abrams, E. M., Chan, E. S., & Sicherer, S. (2020). Peanut allergy: New advances and ongoing controversies. Pediatrics, 145, e20192102, doi: https://doi.org/10.1542/peds.2019-2102

 

 

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