277 ‒ Food allergies: causes, prevention, and treatment with immunotherapy | Kari Nadeau, M.D., Ph.D

Added: Oct 30, 2023

Dr. Nadeau begins by explaining the different types of immunoglobulins, or antibodies, in our blood that help protect us. These include IgG, IgA, IgM, and IgE. While IgG and IgA are protective antibodies found in high concentrations, IgM is the first responder to infections, and IgE is associated with allergies.

The immune system plays a crucial role in fighting off infections caused by viruses, bacteria, and fungi. When a pathogen enters the body, immune cells called macrophages engulf and break it down into small pieces. These pieces, known as antigens, are then presented to T cells, which educate themselves on how to fight the specific pathogen. Memory T cells then teach B cells to produce antibodies, which bind to the antigens and mark them for destruction by other immune cells.

Dr. Nadeau explains that food sensitivities and food allergies are different. Food sensitivities involve reactions to chemicals in food, such as sugars, fats, or spices, and can cause symptoms like bloating or headaches. These reactions are not mediated by IgE antibodies and do not typically result in life-threatening reactions. On the other hand, food allergies involve an immune response mediated by IgE antibodies, which can cause severe allergic reactions, including anaphylaxis.

Celiac disease is a specific type of food sensitivity that involves a reaction to gluten, a protein found in wheat. It is characterized by damage to the small intestine and can lead to long-term health problems. Celiac disease requires a specific diagnosis and management by a healthcare professional.

The prevalence of food sensitivities and celiac disease seems to be increasing, possibly due to better awareness and diagnostics. Additionally, changes in food processing and the presence of chemicals in our food supply may contribute to the rise in food sensitivities.

While food allergies can be life-threatening, Dr. Nadeau reassures that fatal reactions are extremely rare. However, it is important for individuals with food allergies to have access to epinephrine auto-injectors (EpiPens) and receive proper guidance on how to manage their allergies.

Dr. Nadeau also discusses the potential for immunotherapy to treat food allergies. Immunotherapy involves exposing individuals to small amounts of the allergen over time to desensitize their immune system. This can be done through oral immunotherapy (OIT), sublingual immunotherapy (SLIT), or epicutaneous immunotherapy (EPIT). Regular and consistent exposure to the allergen is crucial for successful desensitization.

The conversation then shifts to the impact of environmental factors, such as air pollution, on allergies and the immune system. Dr. Nadeau explains that air pollution can exacerbate allergies and asthma by triggering inflammation in the airways. It can also affect the immune system's response to allergens. Further research is needed to fully understand the mechanisms and develop strategies to mitigate the effects of air pollution on allergies.

Dr. Nadeau emphasizes the importance of a healthy lifestyle, including good sleep, a nutritious diet, regular exercise, and stress management, in supporting a healthy immune system. These factors can help strengthen the immune system's ability to fight infections and reduce the risk of allergies.

Dr. Nadeau highlights the increasing incidence and prevalence of food allergies in the United States. She mentions a study by her colleague, Ruchi Gupta, which found that one in every 12 children in the U.S. has a doctor's diagnosis of food allergy. She also notes that the traditional belief that children would outgrow milk and egg allergies by their teenage years is no longer accurate, as there is now a 50% chance of retaining these allergies. Additionally, more adults are developing food allergies, with an estimated one in 30 adults having some type of food allergy.

The discussion then focuses on the immune system's reaction to food allergies, using peanuts as an example. Dr. Nadeau explains that when a person with a peanut allergy is exposed to peanuts, their immune system reacts as if it is a parasite or mosquito bite. This reaction involves the production of IgE antibodies, which bind to the peanut protein and trigger the release of histamine and other chemicals. This can lead to symptoms such as swelling, mucus production, itching, and, in severe cases, fatal reactions.

Dr. Nadeau also discusses the role of environmental factors in predisposing individuals to food allergies. She mentions that dry skin, exposure to certain detergents, lack of good microbiome, and low vitamin D levels can all contribute to the development of food allergies. She emphasizes the importance of diversifying the diet early and regularly to prevent food allergies.

The conversation then shifts to the topic of early exposure to nuts as a means of preventing allergies. Dr. Nadeau explains that previous guidelines recommending avoidance of allergenic foods in early childhood were based on limited data and have been found to be ineffective. Current guidelines now encourage early and regular exposure to allergenic foods, such as peanuts, to promote tolerance and prevent allergies. She also mentions the role of breastfeeding in promoting a healthy immune system but notes that it has not been definitively shown to prevent food allergies.

Dr. Nadeau then discusses the revolution in food allergy treatment, particularly through immunotherapy. She explains that immunotherapy involves giving the person small amounts of the allergen to retrain their immune system. This can be done through injections for environmental allergies or orally for food allergies. The dose is gradually increased over time to build up tolerance. Dr. Nadeau emphasizes the importance of conducting immunotherapy under medical supervision and notes that the duration of treatment varies depending on the individual.

Dr. Nadeau then delves into the causes of food allergies, highlighting the role of genetics and environmental factors. She explains that genetics play a significant role in determining a person's susceptibility to allergies, but environmental factors, such as air pollution and changes in the gut microbiome, also contribute to the development of allergies. She emphasizes that the rise in food allergies cannot be solely attributed to genetics and that environmental factors play a crucial role.

Moving on to prevention, Dr. Nadeau discusses the concept of the "hygiene hypothesis," which suggests that reduced exposure to germs and infections in early childhood may lead to an overactive immune system and an increased risk of allergies. She explains that exposure to a diverse range of microbes and allergens early in life can help train the immune system to tolerate these substances and reduce the risk of developing allergies. She also emphasizes the importance of breastfeeding and introducing allergenic foods early in a child's diet to promote tolerance.

The main focus of the podcast is on the treatment of food allergies through immunotherapy. Dr. Nadeau explains that immunotherapy involves gradually exposing the immune system to small amounts of the allergen to desensitize the body's response. She describes a specific immunotherapy protocol called oral immunotherapy, which involves giving patients small doses of the allergen, such as peanuts, and gradually increasing the dose over time. This process helps the immune system build tolerance to the allergen and reduces the risk of severe reactions.

Dr. Nadeau shares a case study of a patient who underwent oral immunotherapy for a peanut allergy. She explains that during the first year of treatment, the patient's immune system gradually adjusted, creating a layer of memory T cells that became tolerant to the allergen. This shift in the immune system resulted in the production of protective molecules, such as immunoglobulins, which prevented the allergen from binding to receptors and causing a reaction. She emphasizes that immunotherapy is a long-term process that requires daily treatment and monitoring.

The podcast also addresses the question of whether immunotherapy can completely eliminate food allergies. Dr. Nadeau explains that while immunotherapy can significantly reduce the risk of severe reactions, it does not guarantee complete elimination of the allergy. However, she notes that with long-term treatment, there is a chance of achieving a level of tolerance where accidental ingestion of the allergen does not cause a reaction.

Dr. Nadeau also discusses the importance of monitoring air pollution, specifically PM 2.5 (particulate matter 2.5 microns in size), which can have detrimental effects on respiratory health and exacerbate allergies. She advises individuals to check air quality indexes and take precautions, such as wearing masks and using air filters, to reduce exposure to pollutants.