Food Allergies, Intolerances, and Sensitivities 101
It’s not uncommon to hear the terms allergy, intolerance, and sensitivity used almost interchangeably when reading or speaking about reactions to food. The problem is that there are differences, and the lack of differentiation can create more confusion regarding how to manage an individual trigger or reduce the chance of a reaction. If you find yourself feeling confused about the nuances of these terms and conditions, you are not alone! Read along to better understand how food allergies, intolerances, and sensitivities differ in their presentations, causes, and methods for management.
A helpful way to look at these three categories of reactions is to consider their impact on the body, as this chart outlines.
|IgE (Immunoglobulin E, a type of antibody) immune-mediated response||Functional response to food molecules||Suspected to be IgG (Immunoglobulin G, a type of antibody) immune-mediated response|
|Immediate, potentially mild, but often serious symptoms may be life-threatening||Not life-threatening, reaction time can range from 1-48 hours||Immediate or delayed symptoms (minutes to days). Not life-threatening|
|Examples: peanuts, bee sting/bee venom||Examples: lactose, histamine||Examples: Soy, food additives|
The eight most common food allergens in the United States are milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish. Family history does seem to play a role in the development of allergies, including a connection with environmental allergies (i.e., hay fever, pollen). 1
By definition, a true allergic response, or allergy, is an overreaction by an individual’s immune system against an otherwise harmless substance, such as a food protein. In people without allergies, these food proteins, such as gluten from wheat or whey from dairy, produce no immune response at all. The most common is an immunoglobulin E (IgE)-mediated allergic reaction. The immune system produces IgE antibodies, which cause an immediate reaction to attack the offending substance (like pollen or peanuts). 1, 2. An allergic reaction can range from mild to severe. A severe reaction may cause intense skin rashes, difficulty breathing, low blood pressure, facial and/or throat swelling. Anaphylaxis is a severe reaction involving more than one part of the body that escalates quickly and can be fatal. 2
Because of the significant risk involved, the only way to prevent a reaction is by strictly avoiding the allergen in all forms. Many allergists strongly recommend someone with an allergy carry Epinephrine shots (EpiPen) in case of accidental ingestion or exposure in order to prevent a potentially life-threatening situation. 3.
It’s believed that allergies may take a few years to develop, and allergy testing may be beneficial as allergies can appear, increase, decrease, and disappear throughout someone’s lifetime. The concept of cross-reactivity, an immune response to similar food proteins or environmental allergens (i.e., pollen), is worth noting for its relevance. While outside the scope of this article, for a brief overview, please visit:
Unlike allergies, tolerance can vary amongst other foods. An intolerance is characterized by an abnormal functional response to a food component that does not involve the immune system. A useful way to remember the differences between an allergic reaction to a food and intolerance is that intolerances are a result of foods not breaking down properly, which is referred to as maldigestion. Sometimes this can be related to the body’s lack of a digestive enzyme needed to separate food components, such as proteins, fats, and carbohydrates, in a way that is most optimal for absorption within the digestive tract.
While total avoidance is required with an allergy, in the case of an intolerance, the amount of the food consumed can have an effect on the intensity of the symptoms experienced. Tolerance varies from person to person and may even vary within a person’s dietary composition when the triggering food is consumed (i.e., on its own or with other foods, in a small quantity vs a larger quantity). 1
A commonly recognized example is lactose intolerance. Individuals with lactose intolerance do not have sufficient lactase, the enzyme required to break down lactose (the primary carbohydrate in milk) into smaller components for proper digestion. Therefore, maldigestion occurs and can be experienced as gas, bloating, abdominal pain, changes to bowel patterns, or other digestive-based symptoms.1 Occasionally, intolerances present in symptoms outside the digestive tract, such as fatigue, brain fog, joint pain, or skin irritation.
Another example of intolerance includes specific types of carbohydrates, often referred to as FODMAPs, which stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. More specifically, this includes fructose, lactose, mannitol, sorbitol GOS, and fructans. 1 A key point worth noting in the case of an intolerance to FODMAPs is the role of bacteria in our digestive tract, or “gut”. Instead of a specific enzyme lacking that leads to maldigestion, the intolerance is connected to bacteria in the gut rapidly fermenting the specific carbohydrates, producing discomfort. As a result, individuals may experience adverse symptoms such as bloating, gas, and changes in bowel motility, such as diarrhea or constipation. A reduction in fodmap-containing foods for a period of 2-6 weeks can provide relief for those sensitive to fodmap-containing foods.4 It’s important to work closely with a Registered Dietitian while following a low-fodmap diet to receive support and ensure accuracy of both elimination and reintroduction. Some individuals diagnosed with irritable bowel syndrome (IBS) have found relief following a low-fodmap diet, but not all IBS cases are remedied through this approach. 4
For more detailed information, visit: https://www.monashfodmap.com/about-fodmap-and-ibs/. 4
Food sensitivities are a less clear concept, as the term does not have an agreed-upon medical or scientific definition. Sensitivities are believed to be linked to an immunoglobulin G – mediated immune response (IgG) and known to be less severe than an IgE (allergic) response, though sometimes have an immediate onset and can be quite problematic.
Some data indicate high levels of antibodies may arise in response to a food that is consumed often (without a reaction) and thus lead to a ‘positive’ result on a food sensitivity test. This has led IgG food testing to remain a grey area in terms of confirming food sensitivities, specifically through the identification of high antibody levels.1
While IgG testing is widely available, at Summerfield, we’ve found more benefit when patients monitor their food and symptoms working alongside a dietitian. Some individuals find relief from symptoms by following an elimination diet protocol. This allows us to identify individual triggers, aiding improvement in symptoms with the goal of establishing the least restrictive dietary approach possible.
One important consideration for food sensitivities and intolerances is that a disruption of the gut microbiota and/or intestinal tissue may play a role. These disruptions may occur as a result of antibiotics, an imbalanced diet, toxin exposure, and even stress. Suboptimal gut bacteria (not enough “good” bacteria or elevated levels of “bad” bacteria) may change how the immune system recognizes and responds to certain foods and other compounds that pose a threat in the digestive tract. Since we know a large portion (70-80%) of our immune system is located intestines, it makes sense that an altered immune response may arise from an imbalanced microbiome.
What else should we know?
The concept of intestinal hyperpermeability (sometimes referred to as leaky gut) is also believed to play a role in food sensitivities for some individuals. In this scenario, irritation/inflammation of the intestinal tissue causes the naturally occurring small spaces in the tissue to widen into larger gaps. These gaps can be thought of as a “break” in the barrier function between our intestines and the circulation outside of them. This allows various substances (i.e., bad bacteria, undigested food particles) to pass through that otherwise would be contained in the digestive tract. The greatest challenge arises when hyperpermeability is not addressed, and food triggers are consumed, promoting a cycle of ongoing inflammation, bacterial imbalances, and problematic symptoms. 1
Individuals with autoimmune conditions often present with intestinal hyperpermeability, chronic inflammation, and suspected food sensitivities linked to various symptoms, including headaches, fatigue, achy joints, digestive upset, skin rashes, and trouble sleeping.1 Remembering that our body is an interconnected network brings us back to the importance of identifying an individual’s unique symptoms and potential triggers.
Often the best way to gather deeper insight into triggers is through a food and symptom journal to allow for the identification of patterns and the strategic removal of food. Through this approach, individuals can monitor for changes/improvements. For many, this practice is most successful when done in partnership with a Registered Dietitian for guidance and support.
In conclusion, reactions to food can vary in terms of classification, severity, symptom type, duration, and how they are most effectively addressed. By now, it is clear some subtleties can make identification and management somewhat challenging. If an allergy is suspected, seek formal testing and ensure protective measures are taken to avoid exposure. For intolerances and sensitivities, it is possible these reactions may be managed through increased awareness of dose tolerance, supporting microbial balance, or could fade over time as the body is rebalanced. For some, avoiding these foods may be the only way to ensure they feel their best.
It can be difficult and time-consuming to understand, but with the right tools and support, many individuals find relief from troubling symptoms and are able to return to a balanced and varied diet. The good news is that our bodies, immune responses, and gut bacteria are continually changing! What feels out of balance now does not guarantee it always will be. Customizing an approach to help you feel your best and enjoy the foods that allow you to do so is the ultimate goal. If you are interested in identifying potential food sensitivities or intolerances, exploring persistent yet unexplainable symptoms, or would like support in reintroducing previously eliminated foods, contact us to meet with a dietitian who can guide you through this experience.