Woman clutching belly from food allergies.

What’s the Difference Between Food Allergies, Sensitivities, and Intolerances?



According to the Food Allergy Research & Education (FARE) organization, approximately 32 million people in the United States have food allergies. This is equivalent to about 10% of the US population. Perhaps you are one of those people diagnosed with a food allergy. If so, maybe you had one of those tests where they stuck needles coated with potential allergens into your back, and you itched like crazy with some of them. Those itchy ones were the food allergens. That itchiness is part of an IgE reaction, where the body identifies an allergen as an outside invader and directs the immune system to attack it. 


When you encounter an allergen, your immune system knows it and launches a chain reaction to defend you. First, it sends a chemical signal to “mast cells” in your skin, lungs, nose, mouth, gut, and blood. The message is, “Release histamines,” which are stored in the mast cells. This release of histamine is designed by the body to send a signal for how the immune system should react to an invader. The problem is its role in causing allergic and anaphylactic symptoms. When your body experiences a trigger to release histamine, it creates inflammation.  In some cases, your body can release excessive amounts of histamine or become unable to break down the histamine released. This can result in symptoms including flushing, hives, itchy skin, and difficulty breathing. That is a classic allergic reaction. In the case of food allergies, it means that eating certain foods, or classes of foods, means that your body wrongly thinks that the food itself is harmful and triggers the body to attack it. The side effects of this action is the inflammation that causes swelling in the skin (hives itchiness, and flushing) and swelling of the throat (difficulty breathing and dizziness). A severe allergic reaction can cause anaphylactic shock and death, and even mild reactions can be unpleasant, and can potentially worsen over time. 


The first time that you eat a food, you may not have an allergic reaction to that food, but over time that same food that once seemed “safe” may now trigger a reaction. Why is that? According to the American College of Allergy, Asthma, & Immunology, food allergy symptoms “can appear at any age”, and, the organization adds, you can develop an allergy to foods you’ve eaten for years with no problem. Experts don’t always know why someone will develop a food allergy as an adult, but people with eczema, asthma, or seasonal allergies seem to be more prone than others. In addition, many foods have cross-reacting antigens that you can also inhale, like tree pollen. One of the pathways of the immune system, the production of IgG4, may also temper specific allergic reactions to some foods and make them less severe or even cause no symptoms at all. 


Allergens aren’t the only culprit when food makes you react. Food sensitivities can also cause an impact on your body, and make you feel terrible. Unlike food allergies, food sensitivities don’t make themselves known immediately. A food you are sensitive to, but not allergic to, will begin to cause symptoms between 3 and 72 hours after you consume it. Because there is such a delay in the onset of reactions, food sensitivities can be much more difficult to tie to specific foods. With allergies, you can look at your plate and greatly narrow the possibilities for what caused you to react, but with sensitivities, anything consumed over the last three days could be the culprit. Unlike food allergies, which activate an IgG reaction, food sensitivities are likely caused by an IgG reaction. Other molecules like IgA can play a role as well, but IgG is the most common culprit. 


Food sensitivities can cause a range of health problems and varied symptoms. Brain fog and lack of clear thinking, faulty memory, tiredness and lack of energy, irritability, bloating, intestinal cramping, watery stools, cracked skin, rashes, puffiness, and other symptoms can all be evidenced after various food sensitivities. Food sensitivities usually begin in the gut, particularly if your microbiome is disturbed. Bouts of food poisoning, antibiotic use, eating too little fiber and too much sugar and processed foods, and illness can all damage the microbiome. A healthy microbiome is necessary to keep a balance of beneficial bacteria and other organisms in the gut to properly digest foods and eliminate waste products, ensuring that you absorb the nutrients you need while adequately getting rid of toxins. A damaged microbiome makes it more likely that you’ll react to various foods, and continuing to eat foods that you react to will further damage the microbiome.


A damaged microbiome doesn’t just affect your extraction of nutrients and elimination of waste products, although that’s bad enough. The inability to extract nutrients efficiently can make you sicker by weakening your immune system, and the accumulation of waste products can increase your toxicity, eventually damaging your liver and kidneys in addition to your gut. A damaged microbiome causes inflammation in the gut and foods that you are sensitive to contribute to inflammation through IgG reactions. Some foods may even trigger the release of C3d (also known as “complement”). The body releases complement to signal to the immune system that a serious threat is present, and to attack hard. The complement release triggers a flood of cytokines, the immune system’s heavy hitters, that flood in. This is also known as a “cytokine storm”, because of the ferocity of the response. In fact, sometimes this “cytokine storm” is too intense, especially in healthy people, and can cause severe damage and inflammation. It’s theorized that “cytokine storms” are the events that may have led to so many deaths of young, healthy people in the 1918 flu pandemic, and why some healthy athletes may have had such strong reactions to COVID-19. In terms of food sensitivities, a complement reaction may supercharge the strength of the immune response (by up to 1,000 times!), and cause worse inflammation in the intestinal wall. 


The constant, or chronic, inflammation of the intestinal wall risks loosening the tight junctions between cells in that wall, allowing leakage of foreign material and foods into the bloodstream (also known as leaky gut), and triggering the release of zonulin. Zonulin is a protein that increases the permeability of tight junctions between cells of the wall of the digestive tract, meaning that its release perpetuates a leaky gut. When zonulin is released, it changes the permeability of intestinal epithelial cells by regulating the state of tight junctions. Increased intestinal permeability can lead to abnormal activation of intestinal mucosal immune and bacterial translocation, then inducing systemic inflammation. In other words, bacteria can spread throughout the body causing inflammation elsewhere in the body, including muscles and other organs. This is why we can feel achy and tired, have brain fog, and just feel bad all over-all from food reactivity. 


Zonulin is the only physiologic modulator of intercellular tight junctions described so far that is involved in the trafficking of macromolecules and, therefore, in tolerance/immune response balance. When the zonulin pathway is deregulated in genetically susceptible individuals, autoimmune disorders can occur1. Both animal studies and human trials using the zonulin synthetic peptide inhibitor AT1001 (now named Larazotide acetate) established that zonulin is integrally involved in the pathogenesis of autoimmune diseases2. This new paradigm subverts traditional theories underlying the development of these diseases and suggests that these processes can be arrested if the interplay between genes and environmental triggers is prevented by re-establishing the zonulin-dependent intestinal barrier function. Both animal models and recent clinical evidence support this new paradigm and provide the rationale for innovative approaches to prevent and treat autoimmune diseases1. So what does this mean? It means, first, that the continued release of zonulin from food sensitivities can not only risk autoimmune diseases of the gut like Crohn’s Disease, and Irritable Bowel Syndrome, but possibly other autoimmune diseases as well. Secondly (and luckily), reversing the release of zonulin in the gut can stop the progression of autoimmune diseases, and stop them from occurring in the first case if you can intervene early enough to stop the opening of tight junctions in the intestines by eliminating foods that you are sensitive to from your diet and by repairing the microbiome. 


What about food intolerances? How are they different? Many people use food intolerance and food sensitivity interchangeably, reasoning that since they are distinct from food allergies they describe the same phenomena. Food intolerances are technically different from food allergies and sensitivities. Both food allergies and food sensitivities are rooted in immune responses, whereas food intolerances are used to describe a condition where a food cannot be broken down by the body, and its nutrients absorbed, most often because a person lacks an enzyme to do so. The most common example is lactose intolerance. Many genetic populations, particularly East Asians, lack enzymes to break down the lactose found in milk (particularly that in cow’s milk), meaning that the energy found in those sugars is not available to them. Other common intolerances are those to gluten, nitrites/nitrates, some preservatives, and to histamines. The symptoms of food intolerances are not potentially deadly, like allergies, nor do they potentially cause systemic chronic inflammation like food sensitivities. Instead, they tend to cause gas and bloating, loose stools, and some discomfort. This is not the same as the type of damage that is done to the intestinal wall by food sensitivities.


So how can you find out if you have food allergies, food sensitivities, or food intolerances, and how do you fix them? The very first thing to do is to have an assessment done through food allergy and sensitivity testing, followed by a consultation with a nutritionist to plan an elimination diet. The gold standard of allergy and sensitivity testing is the P88 test offered by Precision Point Diagnostics and available through Progressive Medical Center both as a test using a phlebotomist in our office as well as the P88-DIY available as a home test for qualified patients through telemedicine. This test evaluates 388 separate reactions involving immune response to foods- both as allergies and as sensitivities. 88 separate foods are evaluated for IgE, IgG, IgG4, and complement specific to each patient. This allows you to find out your food allergies (IgE), sensitivities (IgG), blocking potential to specific food allergies (IgG4), and whether complement is likely to exacerbate the severity of the reaction (C3d). Based on this test, which comes with a comprehensive color-coded report, the nutritionists at Progressive Medical Center will set up an elimination diet for each patient. 


An elimination diet is a key step to help repair the microbiome and intestinal lining of the gut. Foods that you tested positive for will be eliminated and gradually reintroduced, both as a check on how well you can tolerate them and to eventually retrain your gut to enjoy many of the foods that used to bother you. Zonulin testing and testing for certain food intolerances (through hydrogen breath testing) are also available. Zonulin testing can help determine how much damage has so far been done to the intestinal wall, and SIBO testing (a hydrogen breath test) can both determine some common food intolerances as well as assess for Small Intestinal Bacterial Overgrowth, another condition that can result from damage to the microbiome and intestinal walls. An elimination diet is also an excellent route for assessing suspected intolerances, although, unlike sensitivities, those foods likely won’t end up back as a regular part of your diet.


Once your testing assesses the state of your allergies, sensitivities, and intolerances, our team will help you repair your microbiome through food elimination and supplementation and eventually reintroduce foods. Not only do most patients feel an alleviation of their symptoms, losing the gut cramping and pain, feeling more regular, more focused, and clear-headed, and seeing clearer skin and less bloating, but many can eventually reintroduce their favorite foods. Schedule your appointment today, or call about our telemedicine program for allergy and food sensitivities!