Podcast Summary: Short Wave – "A Surprising Culprit of Food Allergies"

Host: Aaron Scott
Guest: Dr. Wahida Samady (Director of Clinical Research, Northwestern University’s Center for Food Allergy and Asthma Research)
Date: September 23, 2025
Duration: ~15 minutes

Overview

In this episode, Short Wave dives into the growing phenomenon of food allergies, exploring why their prevalence is rising, the biological mechanisms behind allergic reactions, and a surprising theory about how we may become allergic to foods. Host Aaron Scott is joined by Dr. Wahida Samady, who shares the latest science and global context on food allergies, including the role of the skin, the environment, and dietary habits around the world.

Key Discussion Points and Insights

1. Food Allergies: The Personal and Scientific Spectrum

• Host’s Experience: Aaron Scott discusses his childhood dairy allergy.
  • "When I was growing up, I was allergic to dairy...my nose would get totally stuffed up." (00:24)
• Severity Can Vary: Dr. Samady outlines the range of food allergy reactions.
  • "There are other people that will describe like a sense of doom almost that kind of comes over them...throat closing...itching and swelling...nausea and vomiting...a whole body takeover." (00:35–01:13)

2. The Food Allergy Epidemic

• Prevalence Has Risen Sharply:
  • "Before the 1990s, the rate...was below 3%...Now, 1 in 13 children have a food allergy." (01:24–01:48)
• Geographical Differences:
  • The rise is concentrated in "America, Western Europe, Australia, and parts of Asia and Africa. But...there are still places...where no one has a food allergy." (01:58)

3. Theories Behind the Increase

• The Mystery:
  • "That is the million dollar question. We have a lot of theories." (02:27)
• Featured Theory:
  • "You absorb the food through your skin before you eat it and then your body decides it is something to attack." (02:40)

4. What Happens During An Allergic Reaction?

• Biological Process (04:13–05:37):
  • Food is broken down in the intestine, then absorbed.
  • Immune cells along the gut label certain foods as threats, releasing chemicals (cytokines).
    • "It’s basically telling your body an invader has come, we have to fight."
  • This triggers inflammatory cascades, leading to swelling, hives, and itching.
  • "One of the products...is histamine. And that's why you get itchy, and that's why you get hives." (05:37)

5. Treating Allergic Reactions

• Mild Reactions:
  • Treated with antihistamines (for itching, hives, rash).
• Severe Reactions:
  • Require epinephrine (adrenaline) via injection.
  • "The other interesting thing about epinephrine is that it will attach to some of those immune cells and stop the progression of an allergic reaction." (06:00–07:00)

6. Why Do Some People Develop Food Allergies?

• High-Risk Indicator:
  • Early, severe eczema in children is a strong predictor.
  • "One of the first signs...is that they have eczema. The earlier you develop eczema, and the more severe...the higher the risk." (07:07–07:42)
  • Gut flora differences noted in children with eczema.
• Skin Barrier Hypothesis:
  • Disrupted skin allows food particles in, teaching immune cells to treat foods as threats.
    • "Food can get into a broken skin barrier...they might label those food proteins as something bad." (08:33–09:01)

7. Global Differences in Food Allergies

• Vary by Region and Culture:
  • Different foods are allergenic in different countries (e.g., lentil/chickpea in India, shellfish in East Asia).
    • "Globally, for example, different countries will have different types of allergic foods." (09:10)
  • Processing methods matter:
    • In the U.S., peanuts are mostly roasted, which may enhance allergenicity versus boiling in other regions.
    • "We do think the roasting process itself makes peanuts...more likely to set off an allergy." (10:17)

8. If You Suspect a Food Allergy

• Seek Medical Advice:
  • Avoid unnecessary dietary restrictions—consult professionals for testing and diagnosis.
  • Some symptoms may not be immediate-type allergies, but rather histamine reactions or oral allergy syndrome.
    • "There are so many people that think they have one of these immediate-type reactions and they don't. But they've been avoiding large groups of foods." (10:29–11:51)

Notable Quotes and Memorable Moments

• "We call it an epidemic because it has risen dramatically over the last few decades."
  – Dr. Wahida Samady (01:24)
• "Some of these symptoms that you're having are just secondary to the inflammation that the body is creating."
  – Dr. Samady (05:10)
• "If you have a disrupted skin barrier and food particles are getting in through the skin...those immune cells...might label those food proteins as something bad."
  – Dr. Samady (07:58–09:01)
• "Different countries will have different types of allergic foods...It's also thoughts about how we process our food."
  – Dr. Samady (09:10–10:17)
• "When you are in a severe reaction, nothing else is really going to take away the reaction or stop it from progressing the way epinephrine would."
  – Dr. Samady (06:54)
• "What I would really recommend...we really should try to find a healthcare provider that can help you get tested."
  – Dr. Samady (10:34–11:51)

Timestamps for Key Segments

• 00:24: Aaron’s personal food allergy story
• 00:35–01:13: Dr. Samady describes severity of reactions
• 01:24: Food allergy statistics and the "epidemic"
• 01:58: Global prevalence differences
• 02:27: Theories behind the rise in food allergies
• 04:13–05:37: What happens biologically during a reaction
• 06:00–07:00: Treatments for mild vs. severe reactions
• 07:07–07:42: Eczema as risk factor; microbiome differences
• 08:33–09:01: Skin barrier theory
• 09:10–10:17: Regional differences in food allergies, peanut processing
• 10:34–11:51: Advice for those who think they have food allergies

Episode Takeaways

• Rising Rates: Food allergies have doubled in children since the 1990s, but this rises mainly in Westernized countries.
• Skin Barrier Theory: Disrupted skin in young children may introduce foods as allergens before oral tolerance is established.
• Diagnosis Matters: Many attribute unrelated symptoms to allergies—proper diagnosis is crucial to avoid unnecessary deprivation of important foods.
• Cultural Context: The foods people are allergic to, and the risk of developing allergies, vary around the world due to diet and food preparation methods.

This engaging episode is accessible for anyone curious about the science behind food allergies, combining personal anecdotes, clear explanations, and the latest hypotheses in allergy research.