What are the Causes of Food Intolerance?

Written By: Jordan Stachel. M.S., RDN, CPT

Food intolerances are any adverse reaction you experience after eating certain foods.[1] These can cause a wide array of reactions to foods, including:

• Metabolic (like lactose intolerance)
• Pharmacologic (like a sensitivity to ingesting too much caffeine and/or an inability for the body to break it down)
• Toxic (like consuming a food that is not able to be digested or has gone bad)
• Other (experiencing symptoms without a pattern or explained culprit that causes some type of discomfort after eating)

Common Causes of Food Intolerances

Food intolerances can be caused by a variety of reasons, including but not limited to:

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome is a common gastrointestinal disorder that affects many people around the world.[4] IBS can be uncomfortable to live with and can be triggered by certain food intake. Many people report that their IBS symptoms tend to worsen around the consistent intake of certain offending foods.[4]

For some, an elimination diet may help determine if certain foods aggravate IBS symptoms. Working with a team of qualified healthcare providers to see if eliminating certain foods such as milk, wheat, and eggs improves gastric functioning could be helpful. However, if you are dealing with IBS and wondering if certain foods exacerbate your gastric symptoms, it is important to take an intuitive approach as IBS is incredibly individualized and can be more evasive with its symptoms and correlating food intake. Thus, if you feel relief from limiting your dairy intake, it is likely helpful to do so, whether you have an actual dairy intolerance or not.

Stress and Gut Health

Psychological well-being can affect overall health and the state of the digestive system. This can lead to questioning if someone has food intolerances when, in actuality, psychological distress and/or stress may be the culprit of exacerbating stomach issues.[5]

In addition, if people believe that they have a food intolerance, this can lead to increased levels of attention, awareness, or general anxiety around food intake, making symptoms worse. For example, if you are worried about the consumption of several foods like gluten, dairy, and eggs due to food intolerances, it may be more stressful to dine out, also exacerbating gastrointestinal symptoms.[5]

Genetics

In the research surrounding food intolerances and genetics, there is still much to be discovered. There is some research around food allergies and the genetic component of them. However, it is unclear whether allergies are genetically linked to food intolerances and/or allergies for certain.[6]

In general, if you are experiencing symptoms of food intolerance, it can be helpful to look at what is happening genetically. For example, if your parents are lactose intolerant and you are also noticing symptoms of discomfort after consuming lactose, there may be a genetic link to lactase enzyme insufficiency in the family. Because this relationship is still in question, it is generally advised to consider food intolerances within a family unit within the context of your specific symptoms and food intake.[6]

Environmental Triggers

If you are experiencing food intolerances, you may wonder if your environment and/or lifestyle contribute. While more research is also needed in this area, some research suggests that having certain exposures, like older siblings and/or pets, can help prevent the development of food allergies.[7] This has a lot to do with how these exposures help to strengthen the gastrointestinal tract and boost immunity. Since the gut is one of the first lines of defense in the body, the state of the gut can impact a person’s susceptibility to food intolerances.[7]

In addition, people may have less of a likelihood of food sensitivities and/or allergies depending on their exposure in utero, through breastmilk, or even on the skin as a baby. For example, if a mom consumes peanuts during pregnancy and while breastfeeding, it may have a protective effect on the baby, and they are less likely to have a food intolerance to peanuts.[7]

Foods Commonly Associated With Food Intolerances

Some of the most common foods associated with food intolerances include:

• High fermentable, oligo-, di-, mono-saccharides, and polyols (FODMAP) foods[8]
• Wheat
• High histamine foods (these are foods like sausage, tuna, cheese, eggplant, avocado, and vinegar)[8]
• Foods with natural or added chemicals (these are foods like cheese, chocolate, banana, tomato, apple, oils, jellies, and soft drinks)

Because food intolerances and associated symptoms are highly individualized, it is best to work with a team of qualified professionals to figure out which next steps are most appropriate for you.

Diagnosing the Cause of Food Intolerance

The diagnostic procedures for food intolerances will vary based on what the team of healthcare providers decides is best for you. Typically, medical history is obtained, and there can be a series of tests completed afterward to help rule out what you are sensitive to. These tests can include breath tests, stool cultures, blood tests, urine tests, imaging of the gastrointestinal tract, and/or an elimination diet.[9]

Your healthcare providers will likely begin with the least invasive options, like elimination and/or blood tests, to help provide directives.

Managing and Preventing Food Intolerance Symptoms

Ultimately, managing and preventing food intolerances should be achieved with the help of a team of qualified healthcare providers. Often, using strategic elimination diets may help people mitigate symptoms without too much trouble.[10] If this is not effective, more tests may be used to determine further what the best course of action could be.

Because intolerances are different from allergies, you need to be able to manage symptoms, but food intolerance symptoms should not pose life-threatening risks to your overall well-being.

How Do Food Intolerances Differ From Food Allergies and Sensitivities?

Food intolerances are different from food allergies, as food intolerances do not evoke an immune response in the body, whereas food allergies do.[2] This means that food intolerances are not likely to cause allergenic responses like hives, itching, swelling, and/or anaphylaxis. Rather, food intolerances may cause different types of symptoms, such as those that affect the gastrointestinal system.

Food allergies and sensitivities also have very different rates of onset. Food allergies are usually experienced by rapid onset of symptoms within minutes after ingesting the offending food source.[2] In food allergies, levels of immunoglobulin E (IgE) increase in the blood. Respiratory symptoms are also common and may affect breathing patterns. In more severe cases, food allergies can cause neurological and/or heart effects that need to be addressed with immediate medical attention.[2]

Food sensitivities are not accompanied by severe, life-threatening symptoms. Rather, they can cause uncomfortable symptoms like bloating or diarrhea that can take place each time the food is consumed and can take several hours to take effect.

Take Control of Your Digestive Health With Everlywell

If you or someone you know thinks that you may be dealing with food intolerances, it is important to seek care. Everlywell has convenient, reliable food intolerance testing options including our at-home Food Sensitivity Test as well as our Food Sensitivity Comprehensive Test that you can take from the comfort of your own home to get started. Take the guesswork out of food intolerances today with Everlywell.

1. Australasian Society of Clinical Immunology and Allergy. Food intolerance. Updated August 2024. Accessed December 16, 2024. Medical Citation URL.
2. Gargano D, Appanna R, Santonicola A, et al. Food allergy and intolerance: a narrative review on nutritional concerns. Nutrients. 2021;13(5):1638. doi:10.3390/nu13051638
3. Singla R, Patton T. Food allergy or food intolerance? A Q&A for parents. UChicago Medicine. Published January 18, 2023. Accessed December 16, 2024. Medical Citation URL.
4. Choung RS, Talley NJ. Food Allergy and Intolerance in IBS. Gastroenterol Hepatol (N Y). 2006;2(10):756-760.
5. Coburn S, Germone M, McGarva J, Taft T. Psychological considerations for food intolerances: celiac sprue, eosinophilic esophagitis, and non-celiac gluten sensitivity. Gastroenterol Clin North Am. 2022;51(4):753-764. doi:10.1016/j.gtc.2022.07.003
6. Li J, Maggadottir SM, Hakonarson H. Are genetic tests informative in predicting food allergy? Curr Opin Allergy Clin Immunol. 2016;16(3):257-264. doi:10.1097/ACI.0000000000000268
7. Benedé S, Blázquez AB, Chiang D, Tordesillas L, Berin MC. The rise of food allergy: environmental factors and emerging treatments. EBioMedicine. 2016;7:27-34. doi:10.1016/j.ebiom.2016.04.012
8. Tuck CJ, Biesiekierski JR, Schmid-Grendelmeier P, Pohl D. Food intolerances. Nutrients. 2019;11(7):1684. doi:10.3390/nu11071684
9. Zopf Y, Baenkler HW, Silbermann A, Hahn EG, Raithel M. The differential diagnosis of food intolerance. Dtsch Arztebl Int. 2009;106(21):359-370. doi:10.3238/arztebl.2009.0359
10. Onyimba F, Crowe SE, Johnson S, Leung J. Food allergies and intolerances: a clinical approach to the diagnosis and management of adverse reactions to food. Clin Gastroenterol Hepatol. 2021;19(11):2230-2240.e1. doi:10.1016/j.cgh.2021.01.025