#277 ‒ Food allergies: causes, prevention, and treatment with immunotherapy | Kari Nadeau, M.D., Ph.D.
Dr. Kari Nadeau, Chair of Environmental Health at Harvard, discusses the immune system's role in food allergies versus sensitivities, highlighting how immunotherapy can treat and potentially cure allergies. She also details the health impacts of rising air pollution (PM2.5) and provides actionable tips for reducing exposure.
Deep Dive Analysis
14 Topic Outline
Kari Nadeau's Background and Motivation for Food Allergy Research
Overview of the Immune System and Immunoglobulins
How the Immune System Fights Viruses, Bacteria, and Fungi
Distinguishing Food Sensitivity from Food Allergy and Celiac Disease
Rising Prevalence and Lethality of Food Allergies
Environmental Factors Contributing to Food Allergies
The Role of Early Food Exposure in Preventing Allergies
Immunotherapy for Food Allergies: Retraining the Immune System
Mechanism and Progression of Food Allergy Immunotherapy
Long-Term Outcomes and Accessibility of Food Allergy Immunotherapy
Understanding Air Pollution and PM 2.5
Health Impacts of PM 2.5 and Mitigation Strategies
Lessons Learned from a Fatal Food Allergy Case
Access to Epinephrine Devices and Immunotherapy Resources
6 Key Concepts
Immunoglobulins (IgG, IgA, IgM, IgE)
Proteins in the blood that protect against infections and allergies. IgG is highly protective and abundant; IgA is secretory, found in organs and breast milk; IgM are 'marines' that respond first to infections; IgE is the least concentrated but most potent, acting as the 'match that lights the fire' behind allergies.
Cellular vs. Humoral Immunity
Cellular immunity involves cells like macrophages and T cells that identify and process foreign invaders. Humoral immunity involves antibodies (immunoglobulins) made by B cells, which float in the blood and bind to specific antigens to mark them for destruction by other immune cells.
Food Sensitivity
A reaction to a chemical, protein, sugar, fat, or spice in food, typically causing symptoms like headaches, bloating, or rashes. It can involve the immune system (e.g., IgGs, cytokines causing chronic inflammation) but does not trigger the life-threatening IgE-mediated allergic pathway.
Food Allergy
A severe, IgE-mediated immune reaction to food proteins, where the body mistakenly identifies a food protein as a threat. This leads to rapid release of histamine and bradykinin from mast cells and basophils, causing symptoms ranging from hives to life-threatening anaphylaxis affecting the lungs and heart.
Dry Skin Hypothesis
The theory that microscopic holes in dry skin allow food proteins (like peanut protein) to enter the body through passive aeration. The immune system, mistaking these proteins for parasites, activates the allergic pathway, leading to IgE production and subsequent allergic reactions upon ingestion.
PM 2.5
Particulate matter measuring 2.5 microns in size, representing tiny particles in air pollution from combustion (cars, industry, wildfires). These particles are small enough to penetrate deep into the lungs and enter the bloodstream, carrying about 200 different chemicals that are harmful to the body.
8 Questions Answered
A food sensitivity is typically a reaction to a chemical, sugar, or fat in food, causing symptoms like bloating or headaches, and may involve low-grade immune inflammation. A food allergy is a severe, IgE-mediated immune response to a food protein that can cause life-threatening anaphylaxis.
The increase in food allergies is largely attributed to environmental factors, including changes in food processing, increased exposure to detergents and pollutants, low vitamin D levels, and a lack of early, diverse dietary exposure, rather than genetics.
Food allergies often begin when food proteins, such as peanut protein, enter the body through microscopic openings in dry skin. The immune system, mistaking these proteins for parasites, produces IgE antibodies, leading to an allergic reaction upon subsequent ingestion of the food.
Yes, food allergies can be treated with immunotherapy, which involves gradually exposing the immune system to small, increasing amounts of the allergen daily. This process retrains the immune system to tolerate the food by switching from an IgE-mediated response to producing protective IgG antibodies.
Current guidelines recommend diversifying a child's diet early and often, introducing common allergenic foods like tree nuts, fish, milk, egg, and peanut in small, regular amounts (every day to every other day) to prevent the development of food allergies.
PM 2.5 particles are small enough to penetrate the lungs and enter the bloodstream, carrying approximately 200 harmful chemicals. Exposure can lead to increased risk of asthma, cardiovascular disease, stroke, and cancer, and is a significant contributor to global mortality.
To reduce exposure to PM 2.5, individuals should monitor local air quality (e.g., via AirNow or Purple Air), wear N95 masks when outdoor air quality is poor, avoid exercising outdoors on high pollution days, and use MERV 13 or higher filters in HVAC systems or stand-alone HEPA filters indoors.
An EpiPen might fail if it has expired, if the dosage is incorrect for the patient's current weight (e.g., using an EpiJr for an adult), or if it is not administered quickly enough. Regular doctor visits are crucial to ensure proper management and updated prescriptions.
25 Actionable Insights
1. Daily Oral Immunotherapy for Allergies
If undergoing food allergy immunotherapy, take small, increasing doses of the specific allergen orally every day under medical supervision to retrain the immune system and build tolerance. This regimen aims to switch the immune response from IgE-mediated reactions to protective IgG molecules over time.
2. Master Epinephrine Use
Educate yourself on the proper use of injectable epinephrine devices and carry them if you or your child has a food allergy, as this is the only thing that can prevent fatal reactions. Know how to use it within a minute and administer a second dose immediately if symptoms don’t improve.
3. Diversify Infant Diet Early
Introduce diverse foods like tree nuts, fish, milk, egg, and peanut in small, regular amounts to children early and often (between four to six months of age) to help prevent the development of food allergies. The gut immune system is meant to tolerize to antigens, unlike the skin.
4. Monitor and Filter Indoor Air
Use an indoor PM2.5 monitor (e.g., Purple Air) to assess your home’s air quality, especially in areas with wildfire smoke or high pollution. If levels are bad, install MERV 13 or higher filters in your HVAC system or use stand-alone HEPA filters to reduce exposure, as 90% of life is spent indoors.
5. Protect Skin Barrier Health
Maintain a healthy skin barrier, especially in infants, as dry skin with microscopic holes can allow food proteins to enter and trigger an allergic response. This skin exposure can initiate the allergic pathway, as the body reacts to food through the skin as if it were a parasite.
6. Update EpiPens, Re-test Allergies
Regularly renew and update your injectable epinephrine devices, ensuring they are not expired and are the correct dosage for the individual’s current weight. Re-test allergies with a doctor, as assumptions about outgrowing allergies can be dangerous and lead to tragic outcomes.
7. Sustain Daily Allergen Intake
After completing food allergy immunotherapy with a doctor, continue to consume a maintenance dose (e.g., one to two nuts) daily. This regular exposure is crucial to sustain the immune system’s tolerance and protection, as stopping therapy can revert the immune system to its original allergic pathway.
8. Avoid Outdoor Exercise in Poor Air
Refrain from exercising outdoors when the Air Quality Index is greater than 50, as even short exposures to polluted air can negatively impact your immune system for a full day. This is because PM2.5 particles can penetrate lungs and affect the body systemically.
9. Check Daily Air Quality Index
Regularly check your local Air Quality Index (AQI) on websites like AirNow or NOAA to understand PM2.5 levels in your region. This knowledge enables informed decisions about outdoor activities and protective measures, as air pollution has significant health impacts.
10. Wear N95 in Yellow AQI
Wear an N95 mask when the Air Quality Index is in the yellow zone or higher to reduce the risk of PM2.5 exposure to your lungs. While not perfect, these masks significantly reduce the inhalation of small particulate matter, especially for children and the elderly.
11. Boost Immune System Naturally
Improve your immune system’s health by prioritizing better sleep, eating a healthy diet, and engaging in regular exercise. These lifestyle factors were shown to make the immune system healthier, better equipped to fight viruses and microbes.
12. Regular Allergist Consultations
Be vigilant about taking yourself or your child to an allergist for ongoing management and diagnosis of food allergies. This ensures proper care and understanding of the disease, which is crucial given the increasing prevalence of food allergies.
13. Embrace “Dirt” for Immunity
Increase exposure to diverse microbes, such as by growing up on farms or with animals like dogs, as this can help reduce the likelihood of developing food allergies. This aligns with the “dirt hypothesis” suggesting early microbial exposure aids immune development.
14. Optimize Vitamin D Levels
Maintain sufficient vitamin D levels in your blood, as adequate vitamin D appears to decrease the risk of developing food allergies. This is a simple, yet impactful, preventative measure.
15. Minimize Detergent, Pollution Exposure
Reduce exposure to harsh detergents, air pollution, and tobacco smoke, as these can cause dry skin and itchiness, potentially contributing to the development of food allergies. These environmental factors can compromise the skin barrier and activate allergic pathways.
16. Choose Natural Skin Emollients
When improving your skin barrier, opt for emollients with natural lipids like ceramides, and avoid petroleum-based products (e.g., Vaseline). Petroleum products can increase skin bacteria and worsen inflammation, making natural lipids a better choice for skin health.
17. Eat Nuts During Pregnancy
Pregnant women without existing nut allergies should consume peanuts and tree nuts, as it is safe and can be healthier due to omega-3s. This practice is now recommended to help prevent food allergies in children.
18. Breastfeed for Immune System
Breastfeed infants if possible, as it contributes to overall gut health and a healthy immune system. While not definitively proven to prevent food allergies, it is very helpful for general immune development.
19. Find Food Allergy Specialists
Search clinicaltrials.gov for ongoing food allergy therapy trials or find specialized food allergy clinics online, such as Latitude, if your current healthcare provider cannot adequately answer your questions. This allows access to pioneering therapies and expert care.
20. Adjust Immunotherapy for Side Effects
If experiencing significant side effects like abdominal pain, hives, or worsening asthma during immunotherapy, work with your doctor to decrease and personalize the dose. This ensures patient comfort and adherence, as some side effects might make continuing the therapy too difficult.
21. Ventilate Home, Check Gas Stoves
Ventilate your home regularly to prevent the accumulation of indoor toxins, and be aware that gas or wood stoves can produce compounds contributing to indoor air pollution. Monitoring indoor air quality can help identify and address these sources.
22. Test for Food Sensitivity
If you experience symptoms like bloating, headaches, or rashes after eating certain foods, get yourself tested by a doctor to rule out a true food allergy. This helps identify potential food sensitivities that affect quality of life.
23. Manage Food Sensitivities by Avoidance
If diagnosed with a food sensitivity, avoid the specific food causing symptoms, as there are currently no cures or therapies other than elimination. This strategy helps alleviate symptoms like bloating, headaches, and rashes.
24. Confirm Celiac with Specialist
Seek a specific diagnosis from a gastroenterology or celiac specialist if you suspect celiac disease, as it requires professional confirmation. If confirmed, ensure family members are tested and you receive proper medical care due to its long-term gut implications.
25. Opt for Eco-Friendly Detergents
Select ecologically friendly detergents for washing clothes and dishes, as they tend to be better for your body. These choices align with reducing exposure to harsh chemicals that can negatively impact skin and overall health.
5 Key Quotes
IgE, unfortunately, in the past, when we were in the field and fighting animals and being out there in the wild, IgE was very hopeful to fight parasites, for example. It was very specific to parasites. And now, unfortunately, IgE still exists in our blood. It represents 0.005% of all the immunoglobulins in our blood. So of all those classes, the IgE is the least represented. It's the least concentrated, but it is unfortunately the most potent. And I call it the match that lights the fire behind allergies.
Kari Nadeau
It's not genetic. 70% to 80% of the time, it's environmentally related. It's not related to genes in the family.
Kari Nadeau
Through the skin, allergies begin. Through the diet, allergies can stay quiet. We now know that the gut is really important for tolerizing to those antigens. The immune system in the gut is meant to tolerize. The immune system in the skin, in our lungs, and in our skin skin is actually meant to be activated and react.
Kari Nadeau
For every IgE molecule, we can make a hundred IgG molecules that protect against that IgE molecule circulating and becoming potent. And that's what's happening during the time of immunotherapy. You're making a huge amount of IgG molecules to bind against that IgE becoming what I call pathological.
Kari Nadeau
Air pollution has now, thanks to a lot of science that you can disaggregate what deaths are due to air pollution versus what deaths are due to tobacco smoke. There's a multiplicity of effect here, but now the epidemiologists really have the data right. And you can sink your teeth into this data and know that it's accurate.
Kari Nadeau
2 Protocols
Food Allergy Immunotherapy Regimen
Kari Nadeau- Start with a very small speck of the specific allergen (e.g., 1/200th of a peanut) given daily.
- Increase the dose by 25% every two weeks, continuing daily administration.
- Administer doses in a doctor's office initially due to the potency of food allergens.
- Monitor blood biomarkers (IgE/IgG levels) every 2-3 months to track immune system changes.
- Adjust dose increases (e.g., doubling or quadrupling) based on immune system switching and patient tolerance.
- Aim to reach a maintenance dose equivalent to 1-2 peanuts (or 600mg) daily by the end of approximately one year.
- After reaching the maintenance threshold, patients can typically continue daily administration at home.
- Continue daily maintenance for at least two years for a 20% chance of complete resolution (cure), or five years for a 60% chance.
Preventing Food Allergies in Children (The 'Ds')
Kari Nadeau- Ensure children have good microbiome exposure (e.g., growing up on farms, with animals like dogs).
- Maintain adequate vitamin D levels in the blood.
- Avoid excessive use of detergents (in clothing, dishwashers) that can cause dry skin.
- Diversify the child's diet early and often, introducing allergenic foods in small, regular amounts between 4-6 months of age.
- Improve skin barrier health by using emollients with natural lipids (e.g., ceramides) and avoiding petroleum or paraffin-based products.