Food Sensitivities, Intolerances, and Allergies: What's the Difference?
Key Takeaways:
A food allergy is an immune-mediated condition and is associated with IgE antibodies for a specific triggering food. It is diagnosed with an IgE blood test, as well as an analysis of symptoms. Food allergy symptoms can range from mild to severe and are generally easy to identify and isolate
A food sensitivity is not an immune mediated condition and is commonly linked to problems with the digestion and metabolism of specific triggering foods. There is no test to diagnose a food sensitivity, but elimination diets can be used to accurately identify triggering foods.
There is a general inconsistency in the medical literature regarding the differences between a food sensitivity and a food intolerance. Some papers use the terms interchangeably, while others describe a food sensitivity as a spectrum, with an intolerance being at the extreme/ severe end. For the purposes of this blog, we will use the term food sensitivity and refer to these conditions as a spectrum.
While our mental health and physical health may seem unrelated, they are actually closely intertwined. How we feel physically has a substantial impact on how we feel mentally. Food allergies and sensitivities are physical conditions with a wide range of symptoms that can impact our mental health. While they may seem interchangeable, they are actually completely different conditions with different causes, mechanisms, and treatments. Knowing the differences and symptoms of each can help you determine if you are suffering from an allergy or sensitivity, and what to do about it.
Food Allergies
Food allergies are usually an immune-mediated condition. 2-5% of adults have a food allergy and 15% of all people with allergies (children and adults) developed them as an adult.2 The most common allergy type are IgE mediated allergies. In these types of allergic reactions, the body views the triggering food as foreign invader. IgE antibodies are produced to help rid the body of the triggering food. An antibody is a cell of the immune system that helps fight infection. IgE antibodies serve as the first line of defense against invaders and are associated with allergies. The most common IgE-mediated food allergies in adults are fish, shellfish, peanuts, and tree nuts.2 Allergists diagnose food allergies using IgE blood tests as well as patient reported symptoms.
IgE antibodies are attached to mast cells and basophils, both cells of the immune system. Upon contact with the allergen, these cells release prostaglandins and leukotrienes, which are inflammatory compounds.3 Remember, during an allergic reaction the body thinks the triggering food is dangerous, and does whatever it takes to rid the body of the allergen. Acute inflammation is a normal immune response that helps to protect the body from foreign invaders. Chronic inflammation (inflammation lasting a few months or even years), contributes to a variety of conditions, including depression and anxiety. The response is systemic and acts on a variety of tissues, resulting in multiple possible symptoms. Common symptoms include swelling of the mouth and throat, tingling in the mouth, hives, and even anaphylaxis. These symptoms appear rapidly, within a few minutes to an hour, and can range from mild to severe. Anaphylaxis is a potentially life-threatening condition characterized by a drop in blood pressure, a rapid pulse, and narrowing of the airways. It requires an immediate dose of epinephrine (a hormone that works to counteract allergic reactions and drops in blood pressure) and medical attention.
Little is known about the cause of food allergies. They are most common in children, and some children out-grow their allergies. Adults, however, can also develop allergies that they did not have as a child. There is emerging evidence that some childhood allergies may be caused by cutaneous contact on individuals with a poor skin barrier or atopic dermatitis, but much more research is needed.3
While there is no conclusive cure for food allergies, there are treatments that help manage symptoms and increase tolerance to triggering foods. The first line of defense is to avoid the triggering food in the diet. Food-specific immunotherapy can be used to increase an individual’s tolerance to the triggering food.3 Food-specific immunotherapy is a treatment for IgE allergies that involves exposing the body to small amounts of the triggering food over time with the goal of desensitization. In other words, the body’s immune system would become accustomed to the triggering food and an allergic reaction would either not occur or be less severe. Oral immunotherapy (ingesting small amounts of the triggering food in extract form) is the most effective, but may result in severe allergic reactions in the build up phase. Sublingual immunotherapy (placing food extracts of the triggering food under the tongue) is less effective than oral immunotherapy, but is also less likely to result in allergic reactions. Epicutaneous immunotherapy (injecting small amounts of the triggering food extract under the skin) results in less allergic reactions than other options, but is less effective in adults at desensitizing the body.3
If you suspect you have a food allergy, stop eating the food and make an appointment with an allergist who can properly test, diagnose, and treat you. If you are having a severe reaction, such as anaphylaxis, call 911 immediately.
Food Sensitivities
Food sensitivities differ from food allergies. They are the most common cause of adverse food reactions.4 They are not an immune mediated condition, meaning that your immune system doesn’t cause the intolerance. Unlike an allergy, the amount of triggering food ingested is correlated with the severity of symptoms (in a true allergy, even a small amount of the triggering food can incite a dangerous response).1 Ignoring a food sensitivity can lead to continual discomfort and constant symptoms. It is estimated that 20% of the population has a food sensitivity.5
Symptoms of food sensitivities are more vague than symptoms of food allergies. They can include constipation, diarrhea, headaches, fatigue, bloating, indigestion, flatulence, and nausea, with the most common being ones that involve the GI tract. Most people have symptoms involving multiple systems. Symptoms can appear fairly soon after ingesting a triggering food or up to a few days later. It can be difficult to pinpoint a food sensitivity because symptoms can be indiscernible and delayed.
Sensitivities can have a wide range of causes. Most food sensitivities are caused by a lack of enzymes or other metabolic conditions. For example, individuals with a lactose intolerance tend to have decreased levels of lactase, the enzyme that breaks down lactose during digestion. Without lactase, lactose is digested by colonic bacteria and produces gas (which can lead to flatulence and bloating, common symptoms).1 Dietary histamine sensitivity impacts individuals who, for an unknown reason, can’t break down histamine efficiently enough during digestion.1 Enzymes are not the only cause for food intolerance. Non-celiac wheat and gluten sensitivity is thought to be linked to a damaged gut microbiota, increased intestinal permeability, and/ or inflammation, though much more research is needed.4
There is currently no cure for food sensitivities. Once one is identified, the triggering food would typically need to be eliminated from the diet to prevent symptoms. Individuals with food sensitivities may be able to identify a threshold level where they can still eat a small portion of the triggering food without experiencing major symptoms.
If you suspect you have a food sensitivity, it may be tempting to order a home food sensitivity testing kit. Unfortunately, there is currently no food sensitivity test that can accurately identify a food sensitivity (see this blog for more information on food sensitivity testing). Instead, talk with your primary care doctor, a nutritionist, or a registered dietician about your concerns. Most nutrition professionals will put patients with a suspected sensitivity on an elimination diet to identify the triggering food. The elimination diet is a short-term dietary protocol in which the patient completely eliminates common triggering foods and then slowly adds them back in, one at a time, to try and isolate their specific problem food.
Because our physical health and mental health are so intertwined, food sensitivities can have a significant impact on how our bodies and minds feel. The fatigue, pain, irritability, and other symptoms caused by a food sensitivity impact how we are able to show up in our lives for ourselves and others. Identifying and eliminating triggering foods can help you improve your mental and physical health. Modyfi offers medical guidance to help you plan out nutrition as part of your treatment plan, to reduce inflammation, and improve your mental health.
References
Gargano, D., Appanna, R., Santonicola, A., De Bartolomeis, F., Stellato, C., Cianferoni, A., Casolaro, V., & Iovino, P. (2021). Food allergy and intolerance: A narrative review on nutritional concerns. Nutrients, 13(5), 1638. https://doi.org/10.3390/nu13051638
Iweala, O. I., Choudhary, S. K., & Commins, S. P. (2018). Food allergy. Current Gastroenterology Reports, 20(5). https://doi.org/10.1007/s11894-018-0624-y
Kanagaratham, C., El Ansari, Y. S., Lewis, O. L., & Oettgen, H. C. (2020). IGE and IGG antibodies as regulators of mast cell and Basophil functions in food allergy. Frontiers in Immunology, 11. https://doi.org/10.3389/fimmu.2020.603050
Tuck, C. J., Biesiekierski, J. R., Schmid-Grendelmeier, P., & Pohl, D. (2019). Food intolerances. Nutrients, 11(7), 1684. https://doi.org/10.3390/nu11071684
Wong, K. H., Horwitz, R., & Soffer, G. K. (2021). Immunoglobulin G Food Testing. Annals of Allergy, Asthma & Immunology, 126(6), 611–612. https://doi.org/10.1016/j.anai.2021.01.022
