Hi Friends, and Happy Halloween!
Welcome to the Gut Advisor Newsletter! In this issue: Focus on food allergies
For anyone new- this is a monthly newsletter where we address new, or older but relevant, research findings as well as summarize recent findings or gut-related news. Here, “gut-related” is broadly interpreted, so we will be covering anything that might affect the gut, both “top down” and bottom up”. This means brain/mind things (‘top down”) such as psychology of stress, resilience, and emotion regulation, as well as body-based things (“bottom up”) including inflammation and typical comorbidities of gut disorders, such as pain conditions and autoimmunity.
This newsletter
Dr. Lisa Goehler
Table of Contents
An overview of food allergies
Food allergies come about when someone’s immune system decides that a harmless food item is dangerous and mounts a response to that item. The response for allergies involves TH2 cell activation (a type of T cell), leading to the production of an antibody type called IgE. IgE antibody is different from IgG antibody, which is involved in responses to infections such as viral or bacterial infections. IgG is the antibody induced by vaccinations, for instance.
IgE binds to mast cells, which live in tissues like the gut, skin, and airways that are in contact with potentially dangerous substances in the environment. Mast cells contain pro-inflammatory substances such as histamine, and when activated by IgE, release them. This causes the symptoms of allergy. In the gut, these symptoms can include pain, cramping, and diarrhea, and if it becomes systemic, may also involve non-gut tissues such as the skin and airways. In serious cases, difficulty breathing, loss of consciousness, and shock can occur.
Why does the immune system think harmless foods are dangerous?
The process the immune system uses to decide if a substance is dangerous involves a kind of two-factor verification. A “sentinel cell” needs to detect that a substance is new or possibly dangerous and “present it” to a T cell — the cell that activates systemic immune responses and activates antibody-making cells. But the T cell will not respond unless the sentinel cell also presents a signal that indicates danger. These signals are induced in sentinel cells by “danger signals,” which can be pathogen products that the immune system knows can be associated with infection or be related to tissue damage.
So most basically, the food antigen is accidentally paired with a danger signal. The main hypothesis for how this comes about involves damage or disruption of one of the barriers, principally the gut, but also the airway or skin barrier (Losol 2023, Wanniang 2023), allowing the induction of the danger signal. In the case of the gut barrier, this disruption could be caused by dysbiosis, for instance due to a poor diet and/or by inflammation and stress.
Is IgE only involved in allergies?
IgE and mast cells help defend against parasites, including worms, malaria, and some diseases carried by ticks, such as Rocky Mountain Spotted Fever, Q fever, Ehrlichiosis, and others (Mukai 2016). We don’t know exactly why this system can respond to food also, but it is hypothesized that some parasites may have components that can cross-react with foods (Mukai 2016). So apparently, the immune system may be mistaking foods for parasites!
What’s the difference between a food allergy and a food intolerance?
Food allergies reliably invoke responses that are clearly mediated by the immune system, such as increases in IgE or hives (Hage 2025). Food sensitivities, or intolerances, occur when symptoms are generated by something other than the immune system. For instance, lactose intolerance, in which people cannot absorb dairy sugars. The unabsorbed lactose feeds microbes, which, as a consequence of their metabolism, cause gas. They also “bloom” — meaning that the colony of lactose-fermenting microbes grows — which could contribute to dysbiosis. The cause of other kinds of sensitivities or intolerances is less clear (Hage 2025). In some cases, the sensitivities may be part of irritable bowel syndrome (Soares 2018). The pathophysiology of food sensitivities is not well understood, and this complicates diagnosis and management, and has also provided lots of opportunities for “snake oil salesmen” to ply their wares.
Is there anything we can do to prevent food allergies?
A key challenge for the immune system is determining what substances are safe and should be tolerated, and which are dangerous and should be attacked or expelled. The immune system learns tolerance during infancy and early childhood (Hund 2025). It seems that exposing children to a wide variety of foods when they are young can protect against the development of food allergies, including during pregnancy and breastfeeding (Hund 2025). Diet diversity can support a healthy, diverse microbe population, which can help maintain gut barrier integrity and keep the gut immune system in a tolerant state (Han 2021).
Stress can contribute to the development of food allergies (Schreier 2014). This may be consequent to the ability of stress to increase gut barrier leakiness and thus increase the likelihood of the pairing of an innocuous food item with a danger signal, inducing an allergy. This means that addressing stress can be part of a strategy to improve allergy symptoms.
Speaking of stress: Socioeconomic disparities and food allergy
In the United States, non-white Americans have higher rates of food allergies and anaphylaxis than do white Americans, and the incidence seems to be higher among people of lower incomes (Jacobs 2024). This implicates stress as an important factor in the pathophysiology and severity of food allergies. Stress may interact with dietary factors, as the Western diet of ultra-processed foods is associated with more food allergies.
The rise of food allergies in "developed" countries
One of the concerning things about food allergies is how much they have been increasing, especially in the “developed” countries such as the United States and Western Europe, and urban parts of China. Why the increase? There are several theories, which are nicely summarized in Losol et al. (2023). They point out that the increase in the incidence of allergies has been too rapid to be accounted for by genetic changes. They point to possible environmental exposures to pollution, household chemicals and hygiene products, and changes in diet (e.g., the Western diet), enzymes, and emulsifiers that could disrupt skin, airway, and gut barriers, leading to this increase in allergic diseases. The implication is that anything we can do to limit exposure to these substances and to protect our gut barrier will be key to preventing and managing food allergies.
“Immunotherapy” for food allergies
The main advice given for food allergies is just to avoid the food. But this can be more difficult than you might think. Foods in restaurants and packaged foods from grocery stores can have allergens hidden in them, making people with allergies constantly vulnerable to accidental exposures (Wanniang 2023). It would be better overall if tolerance to the food could be restored. This is the goal of “immunotherapy.”
I was curious as to what this actually is and was a little surprised to find that it is mostly a version, for food allergies, of the “allergy shots” people have been given for decades. Some of the newer “biological” drugs are still being tested but are not widely used, and there are not many data yet on their efficacy.
A recent meta-analysis (De Silva et al. 2022) reports that oral immunotherapy can increase tolerance for peanut, cow’s milk, and egg allergies, and seems to be safe. On the other hand, Wanniang et al. (2023) point out that implementing oral immunotherapy can be difficult in real life due to a lack of widespread training of professionals and gaps in our knowledge of which patients might benefit most, as well as other aspects such as what age is best for oral immunotherapy and protocols such as maintenance doses, etc.
So it does seem that there is hope on the horizon for restoring immune tolerance for foods, but there is still a ways to go. I, for one, am glad there now seems to be a serious effort among practitioners and researchers in this direction.
IgG levels in blood or hair can tell you foods you are sensitive to.
As noted previously, for anyone having non-specific gut symptoms, it is really hard to know what causes them. We tend to attribute symptoms we have to the last thing we ate. This is a core feature of “conditioned taste aversion” or “bait shyness,” and it seems to be a very basic kind of association. Studies with many species, including humans, have reliably demonstrated that experimentally induced gut symptoms are blamed on the last thing eaten. This is especially true if the food is new or has a strong flavor, such as garlic.
But some food allergies — for instance, the “alpha-gal syndrome” discussed here under Journal Club — produce their reactions several hours after eating the allergenic food, leaving plenty of time to eat something else. So it can be difficult to know what is really causing the problem. Food sensitivities can be particularly difficult, as there is no obvious allergic reaction, just the gut symptoms. It would be nice if there were a biomarker that could be used as a test to provide an answer. There still isn’t, but there are companies that will sell you tests for them.
For instance, Amazon.com sells testing kits claiming to detect IgG in blood (or hair!) that target food antigens, and these (despite NOT being IgE antibodies) can tell you what foods you react to. Some examples:
“5Strands Food Intolerance Test, Accurate Hair Analysis, 658 Items Tested, at Home Food Sensitivity Test Kit for Adults & Kids, Gut Health Test, Results in 4 Days.”
“Everlywell Food Sensitivity Comprehensive Test — Learn How Your Body Responds to 204 Different Foods — at-Home Collection Kit — CLIA-Certified Labs — Ages 18+.”
Can circulating IgG and hair kits really tell you what your sensitivities are?
It is important to understand that this test has never been scientifically proven to be able to accomplish what it reports to do. The scientific studies that are provided to support the use of this test are often out of date, in non-reputable journals and many have not even used the IgG test in question. The presence of IgG is likely a normal response of the immune system to exposure to food. In fact, higher levels of IgG4 to foods may simply be associated with tolerance to those foods.
Due to the lack of evidence to support its use, many organizations, including the American Academy of Allergy, Asthma & Immunology and the Canadian Society of Allergy and Clinical Immunology have recommended against using IgG testing to diagnose food allergies or food intolerances / sensitivities.
I couldn’t say it better!
Basically, having antibodies to food items does not necessarily mean your immune system reacts and causes symptoms to that food (Leviatan 2022). IgG levels correspond mostly to what you eat.
Every month, we pick a published (and peer reviewed) article to highlight and discuss.
This month’s selected article
Title
The Meat of the Matter: Understanding and Managing Alpha-Gal Syndrome
Authors
Macdougall JD, Thomas KO, Iweala OI.
Publication
Immunotargets Ther. 2022 Sep 15
This article reviews what is known about the pathophysiology of the syndrome, risk factors, and a variety of new treatment approaches.
I think this paper is worth a read! Check it out →
This last August, The New York Times published an article entitled “Why Is Martha’s Vineyard Going Vegan? It’s All About Tick Bites.”
(https://www.nytimes.com/2025/08/12/dining/marthasvineyard-alpha-gal-tick-bites.html)
Tick bites can induce “alpha-gal syndrome,” which is an allergy to red (mammal) meat and can include reactions to dairy and other animal products as well. The prevalence of this allergy is increasing remarkably all across the country. I have it, as does my son-in-law and several friends. There are some peculiarities to this allergy syndrome that make it important to know about — even if you don’t have it. Yet.
Key points
Symptoms associated with alpha-gal can vary from mild/moderate GI pain, diarrhea, hives, and angioedema to anaphylaxis (throat swelling, difficulty breathing, loss of consciousness, low blood pressure, shock). The most common symptoms are cutaneous (e.g., hives, 70–90%) and gastrointestinal symptoms (70+%), although roughly one-third to one-half of cases (depending on samples reported) also involve symptoms of anaphylaxis.
The mechanism of sensitization and development of the allergy process is not well established. One fun fact: the presence of anti–alpha-gal antibodies can protect against malaria. They may also protect against mycobacterial infections.
The leading hypothesis involves tick saliva (yes, ticks have saliva!) that contains alpha-gal, which, especially as the tick “continues to feed” (!!), comes in contact with immune cells, activating the pathway to allergy. Many different ticks worldwide can induce alpha-gal syndrome in humans.
Sensitization to alpha-gal (a carbohydrate) does not necessarily induce symptoms, and titers of antibody (IgE) don’t correlate well with symptom severity. This ambiguity makes it hard to predict the risks and course of any case of alpha-gal syndrome. Clearly, there are other factors involved.
Interestingly, though, a study of 1,112 adults who reported GI symptoms found that about one-third had low levels of circulating alpha-gal. A follow-up of 112 of the alpha-gal–positive people reported improvements in symptoms “reminiscent of irritable bowel” in 82% of those who eliminated red meat from their diet. So low levels of alpha-gal titers may not be benign and could account for unexplained GI symptoms.
Risk factors identified for the allergy include being male; hypersensitivity to medications including the cancer chemotherapy agent cetuximab and medications that contain gelatin; A and O blood types (most of us); a history of bioprosthetic bovine/porcine heart valves; rural outdoor jobs; and a history of idiopathic (unexplained) anaphylaxis.
Alpha-gal syndrome is the leading cause of anaphylaxis in the southern U.S. Interestingly, “idiopathic anaphylaxis” cases seem to be declining while alpha-gal–induced anaphylaxis cases are increasing, suggesting that many cases of “idiopathic anaphylaxis” may have actually been undiagnosed alpha-gal reactions.
Unlike most food allergies, in which symptoms manifest within minutes, alpha-gal symptoms usually take at least two to three hours. How fast the symptoms appear may relate to the amount of alpha-gal in the food. For instance, organ meat is very rich in alpha-gal. Alcohol consumption and exercise may also speed up the process.
Management of alpha-gal syndrome centers on avoiding red meat, especially organ meats and fattier cuts of meat. This may seem easy, but there can be hidden sources of alpha-gal in medications and commercial foods such as bacon, lard, beef broth, and even in casings for poultry or “vegetarian” sausages.
Dairy does not need to be routinely avoided unless the person reacts to it in the strict absence of any other potential alpha-gal source (about 20% of cases). In those cases, dairy must be strictly avoided. For non–dairy-sensitive alpha-gal syndrome, moderate intake of dairy was associated with an increased likelihood of spontaneous remission.
There seems to be a pretty wide variance in severity of alpha gal reactions, as well as sensitivity to animal products. Clearly, there is more we need to know about this relatively new but spreading syndrome.
Going to restaurants with allergies
Here we will pass on “tips” or observations from practitioners or patients about approaches they found helpful for dealing with symptoms of gut problems or ways to keep the gut healthy that have not yet been tested with clinical trials. So, the evidence is anecdotal but may be worth trying.
If you or your child has an allergy, food labels need to be read, and restaurant servers need to be asked about specific ingredients included in the dishes offered. As someone with alpha-gal syndrome, I have found that it is not enough to ask a server if there is any meat in a dish. I have to ask — is there any bacon, lard, beef broth, etc.? And the server may need to ask the cooks. Which is fine!
As someone who has alpha-gal syndrome, I can tell you that it can come as quite a shock to realize you will likely never eat red meat again. What to eat instead? There are a fair number of “plant-based meat substitutes” out there, but I have concerns about what kind of ultra-processing and additives can turn vegetables or poultry into something that looks and tastes like meat. I found when it did taste like meat, I didn’t want it because it made me afraid it might really be meat. I am quite afraid of eating meat now. So—I have substituted mushrooms for meat in all my recipes. Portobellos, in particular, are nutritionally comparable to beef, and they are “meaty,” with a nice umami protein vibe. Anything I would do with beef, I can do with portobellos. And the upside is that my gut seems to prefer mushrooms to meat. Since I got alpha-gal, my gut is happier than it has been in many decades—probably since the 1980s. One of the great things, too, is that mushrooms are getting trendy, and so it is fairly easy to find many different kinds to suit your tastes.
If anyone has any other tips for how to deal with food allergies or other gut issues, please do not hesitate to send them to [email protected].
I won’t mention your name if you don’t want me to.
Thanks!
Do you have a tip for us? Let us know!
Every month we will highlight an easy to make, gut-healthy dish that we are eating now!
Spicy sweet potato burrito bowls
This recipe is inspired by a restaurant in Staunton, Virginia, that offers spicy sweet potatoes in some of their dishes. I ordered some as a side to put in my burrito bowl. Delicious. This is my rendition of a burrito bowl with spicy sweet potatoes, mushrooms, and squash or eggplant. Most of the ingredients can be prepared ahead and served warm or cold.
It’s a burrito bowl, so it’s a bit “freewheeling.” Spices are “to taste,” as some people like burrito bowls very hot and spicy, and other people need them to be milder. Some people like beans better than rice. Burrito bowls can be made however you like them.
Ingredients
1 large sweet potato
Cherry tomatoes, roasted, about 4 per bowl
Firm squash, like yellow squash, and/or eggplant
Roasted mushrooms
Black or wild rice (1 cup uncooked)
Black beans, 1 15.5 oz can
Green onions, about one per bowl
Oregano Garlic powder
Ancho chile powder
Tomatillo sauce , divided
Queso fresca or pepper jack
Garnish with
Blue corn tortilla chips
Your favorite salsa
Cilantro or basil, chopped
Steps
Slice the sweet potato crosswise to make ½ inch large circles. Spray a roasting pan and place the slices in it, and drizzle with olive oil. Roast at 350 degrees for about 30 minutes.
When cool, pull the skins off, cut the slices into cubes, and toss in olive oil, about ¼ tsp ancho powder and garlic powder.
Place cherry tomatoes in a roasting pan, or other roasting dish. Drizzle with olive oil and toss to coat. Roast for about 20 minutes, when they are looking flatter on the bottom.
Roast the mushrooms and squash or eggplant. They can be roasted separately or together, and this can be done ahead. Cut them in ½ inch chunks, toss in olive oil and garlic powder, oregano and ancho (to taste and if desired)
Cook the rice according to package directions. When rice has absorbed most of the water, add ½ cup or so of tomatillo sauce, and cover. Ten minutes later, add the roasted mushroom and squash/eggplant, 1 tablespoon oregano, and stir well. It can stay warm on the lowest stove setting.
Drain the black beans, and heat in a small sauce pan. Add ½ cup or so of tomatillo sauce, and 1 tablespoon oregano.
To assemble: Layer rice mixture and beans in a bowl. Add cheese, green onions, squash, and roasted tomatoes
Garnish as you like!
Enjoy!
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About the Author
Lisa E. Goehler, Ph.D. is a neuroscientist and expert in the science and treatment of psychological stress, chronic inflammation, and gut-related disorders. She pioneered the study of how GI-tract related bacteria can interact with the brain to lower mood and increase anxiety. Throughout her career, she authored over fifty publications and contributed to peer review for scientific journals and funding agencies, including the National Institute for Health.
References
Bartha I, Almulhem N, Santos AF. Feast for thought: A comprehensive review of food allergy 2021-2023. J Allergy Clin Immunol. 2024 Mar;153(3):576-594.
de Silva D, Rodríguez Del Río P, de Jong NW, Khaleva E, Singh C, Nowak-Wegrzyn A, Muraro A, Begin P, Pajno G, Fiocchi A, Sanchez A, Jones C, Nilsson C, Bindslev-Jensen C, Wong G, Sampson H, Beyer K, Marchisotto MJ, Fernandez Rivas M, Meyer R, Lau S, Nurmatov U, Roberts G; GA2LEN Food Allergy Guidelines Group. Allergen immunotherapy and/or biologicals for IgE-mediated food allergy: A systematic review and meta-analysis. Allergy. 2022 Jun;77(6):1852-1862.
Hage G, Sacre Y, Haddad J, Hajj M, Sayegh LN, Fakhoury-Sayegh N. Food Hypersensitivity: Distinguishing Allergy from Intolerance, Main Characteristics, and Symptoms—A Narrative Review. Nutrients. 2025 Apr 16;17(8):1359.
Han P, Gu JQ, Li LS, Wang XY, Wang HT, Wang Y, Chang C, Sun JL. The Association Between Intestinal Bacteria and Allergic Diseases—Cause or Consequence? Front Cell Infect Microbiol. 2021 Apr 15;11:650893.
Hund SK, Sampath V, Zhou X, Thai B, Desai K, Nadeau KC. Scientific developments in understanding food allergy prevention, diagnosis, and treatment. Front Immunol. 2025 Apr 22;16:1572283.
Jacobs SR, Ramsey N, Bagnato M, Pitt T, Davis CM. Health disparities in allergic diseases. Curr Opin Allergy Clin Immunol. 2024 Apr 1;24(2):94-101.
Leviatan S, Vogl T, Klompus S, Kalka IN, Weinberger A, Segal E. Allergenic food protein consumption is associated with systemic IgG antibody responses in non-allergic individuals. Immunity. 2022 Dec 13;55(12):2454-2469.e6. doi: 10.1016/j.immuni.2022.11.004. Epub 2022 Dec 5. PMID: 36473469; PMCID: PMC12103637.
Losol P, Sokolowska M, Hwang YK, Ogulur I, Mitamura Y, Yazici D, Pat Y, Radzikowska U, Ardicli S, Yoon JE, Choi JP, Kim SH, van de Veen W, Akdis M, Chang YS, Akdis CA. Epithelial Barrier Theory: The Role of Exposome, Microbiome, and Barrier Function in Allergic Diseases. Allergy Asthma Immunol Res. 2023 Nov;15(6):705-724.
Mukai K, Tsai M, Starkl P, Marichal T, Galli SJ. IgE and mast cells in host defense against parasites and venoms. Semin Immunopathol. 2016 Sep;38(5):581-603.
Schreier HM, Wright RJ. Stress and food allergy: mechanistic considerations. Ann Allergy Asthma Immunol. 2014 Apr;112(4):296-301.
Soares RLS. Irritable bowel syndrome, food intolerance and non-celiac gluten sensitivity. A new clinical challenge. Arq Gastroenterol. 2018 Oct-Dec;55(4):417-422.
Wanniang N, Boehm TM, Codreanu-Morel F, Divaret-Chauveau A, Assugeni I, Hilger C, Kuehn A. Immune signatures predicting the clinical outcome of peanut oral immunotherapy: where we stand. Front Allergy. 2023 Oct 2;4:1270344. doi: 10.3389/falgy.2023.1270344. PMID: 37849958; PMCID: PMC10577271.