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Ask Stanford Med: Pediatric immunologist answers your questions about food allergy research

Food allergies affect millions of children, who find it difficult to enjoy ordinary activities like birthday parties and restaurant meals because of worries that something they eat could send them into anaphylactic shock. As the New York Times described recently, Stanford scientist Kari Nadeau, MD, PhD, is studying how to desensitize children to their allergy triggers. Here on Scope, she recently took questions on food allergies and her desensitization research.

Many readers asked how they could enroll in Nadeau’s research or in similar allergy treatment trials near their homes. Information for prospective study subjects around the world is available here; enter “food allergy” in the “Search for Studies” field, and after searching, click the “On a Map” tab to see trials grouped by location. For those who live near Stanford, go here for details on participating in Nadeau’s research.

Below are Nadeau’s responses to a selection of questions submitted using the hashtag #AskSUMed the comments section on Scope. As a reminder, Nadeau’s answers are meant to offer medical information, not medical advice. They’re not meant to replace the evaluation and determination of your doctor, who will address your specific medical needs and can make a diagnosis and provide appropriate care.

@vikas_aditya asks: What’s the simplest way to identify the cause of an allergy in kids?

If you suspect an allergy to a specific food or environmental cause, skin prick testing is the simplest and least invasive way to initially identify the allergy but it is not the gold standard. A food challenge in the doctor's office is the true way to test for food allergies.

Elizabeth P. asks: Is there anyone working to find the exact cause of why so many children, teens and adults are developing life-threatening food allergies today? On a related note, @ceband asks: What do you think of the theory that altered gut microbiomes have led to the rise in allergies and autoimmune disease?

Many scientists and researchers are trying to understand the rising prevalence of food allergies in children. Though there are many theories regarding the increase in this prevalence, we still lack definitive answers. Hypotheses have focused on hygiene, dietary fat, antioxidants, vitamin D and dual-allergen-exposure. Altered gut microbiomes might play a role. It does not appear that genetically modified foods are directly linked to food allergies.

Julie Barnes asks: I am currently pregnant and am wondering if I will possibly be creating a food allergy in my unborn child if I avoid all dairy and egg while pregnant and breastfeeding.

There is recent evidence that a diet in pregnancy and during breastfeeding that is high in Vitamin D, follows features of a Mediterranean diet and includes probiotics may be helpful to prevent asthma and allergies. And a healthy, balanced diet is important to your overall health and the health of your baby. However, we do not have evidence that mothers will create food allergies by food avoidance in pregnancy or breasfeeding. Similarly, there is no evidence from the general population that mothers can create food allergies by eating certain foods during pregnancy or breastfeeding.

Wing-Yee Fu asks: Can adults develop sensitivities if they don’t eat certain food groups for a period of time? I have noticed that I develop hives when I ingest dairy and soy, when in the past I am not allergic.

It is uncommon to develop a true allergy to a food that you previously ate and tolerated. However, if you think you have developed a new food allergy, please go see an allergy specialist.

Clara Luu asks: What do you know about food allergies and certain types of skin conditions? Do lots of people have mild food allergies that cause common conditions such as irritable skin? On a related note, Hilary Paterson asks: My 3-year-old daughter is allergic to peanuts. She has had eczema since she was a small baby. It used to be quite severe but has almost disappeared. Is this a sign that her allergy could be weakening, or simply because she has not had any peanut products since her diagnosis?

The term atopy refers to a predisposition toward developing certain allergic hypersensitivity reactions. A person with atopy usually presents with one or more of the following: eczema (atopic dermatitis), allergic rhinitis (hay fever), allergic conjunctivitis, or allergic asthma. Patients with atopy have a tendency to have food allergies.

Hilary, a baby's eczema often improves with age; however, I would NOT assume that her peanut allergy has also weakened. The only way to accurately diagnose the current state of her peanut allergy is to do a food challenge in a doctor's office.

Karen moloney asks: My son has allergies to milk, eggs, nuts, tree nuts and sesame seeds as well as asthma and inhalant allergens. What are your thoughts on Vitamin D and probiotics?

There is recent evidence suggesting that during pregnancy and breastfeeding, a diet high in Vitamin D and probiotics may be helpful in preventing the development of asthma and allergies. However, Vitamin D and probiotics have not been shown to alter the course of existing food allergies.

Monica Frazier asks: Is there any precedence for desensitization therapy for non-immunoglobin E mediated allergies, like Food Protein-Induced Enterocolitis Syndrome?

Food allergen desensitization has not been utilized as a therapeutic modality for the management of food protein-induced enterocolitis syndrome, food protein-induced allergic proctocolitis, or food protein-induced enteropathy syndrome.

Alison asks: What about children who have strong immunoglobulin-E (IgE) reactions (confirmed severe allergic reactions, and not just high IgE levels) to most foods as well as severe Eosinophilic disorders (EGE in our case)? Are there any studies or research being done for these cross-over kids?

Although the pathogenesis and immune basis of IgE-mediated food allergic disorders and eosinophilic gastrointestinal diseases (EGIDs) is understood to be different, food allergens are relevant in both disorders. Specific IgE testing, and skin prick testing to food allergens play a central role in identifying IgE-mediated food allergies. These tests are also used to identify potentially relevant foods in EGIDs and in designing an elimination diet. Although food allergen desensitization is being studied for the management of IgE-mediated food allergies, it is not being utilized for management of EGIDs. At this time, research efforts have focused on studying these 2 disease entities separately.

Sanda Preuett-Shea asks: Are there any longitudinal studies on animals using oral immunotherapy? What is the longest study on humans and oral immunotherapy?

No, there have not been any longitudinal studies in animals. The longest study of oral immunotherapy in humans is about three years.

Sarah Foote, Leslie Olsen, Anne, Veronique P and Jodi Pritchett ask: What about age restrictions for participants in your research? Are the trials are open to very young children, adults and the elderly?

The Nadeau lab has several ongoing studies. The age requirements differ depending on the study. Certain trials will be available for really young children, and also for adults and elderly patients.

Laura asks: If the [current multi-allergy] study is a success, how long would it take for the FDA to approve this as a standardized treatment? On a related note, Stephanie C asks: Will time have run out for non-pediatric allergy patients by the time this is finally approved for widespread treatment? Is there a window of effectiveness in different age groups?

If studies on food allergen desensitization continue to yield promising results, one estimate is that it might take over 10 years for the FDA to approve this treatment as standardized therapy. At this stage there is no data strongly suggesting that food allergen desensitization only works in the pediatric population. Food allergen desensitization studies have shown benefit in both pediatric and adult subjects. Further research will need to be conducted to better understand differences in the efficacy of food allergen desensitization in different age groups.

Previously: Ask Stanford Med: Pediatric immunologist taking questions on children's food allergy research, A mom's perspective on a food allergy trial and Searching for a cure for pediatric food allergies
Photo by michelle@TNS

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