Adverse Food Reactions: All The Crucial Facts You Should Know

by | Jun 28, 2022 | IBD | 0 comments

Did you know that adverse food reactions cause approximately 200,000 emergency room visits and 50,000 hospitalizations yearly in the United States? While these are just numbers to some people, others can’t help but worry about what types of food reactions they may have. 

This article explains the different types of adverse food reactions and how to improve them if you struggle with one.

What Are Adverse Food Reactions?

Adverse food reactions are any type of reaction that you have to a food that you consume. The reaction can be anything from a minor stomach ache to anaphylactic shock. 

Adverse food reactions are often mistaken for allergies, but they can occur in people who do not have allergies.

Types Of Adverse Food Reactions

There are two main types of adverse food reactions: immune-mediated and non-immune-mediated. If you are a visual learner- you can also check out this chart breakdown here in figure 1. 


Immune-mediated reactions are caused by your immune system overreacting to a protein antigen in the food that it mistakes for a threat. They are further divided into four main types:

  • IgE Mediated

It’s the most common and occurs when the body produces IgE antibodies in response to a particular food protein. These reactions can be either immediate, occurring within minutes to hours after ingestion, or delayed, occurring 6-8 hours or even days later. Symptoms can range from mild (hives, itching, swelling) to severe (anaphylaxis, i.e., difficulty breathing or swallowing).

  • Mixed IgE And Non-IgE

Mixed IgE and non-IgE adverse food reactions present symptoms manifested in both IgE mediated and non-IgE mediated reactions

  • Non-IgE Mediated

They’re less well-known but can be just as serious. They are caused by other inflammatory mediators such as histamine. Non-IgE-mediated food hypersensitivity are typically delayed from hours to weeks after ingestion of the culprit food(s); however, certain types can even cause anaphylaxis like responses also. Symptoms can range from gastrointestinal upset (nausea, vomiting, diarrhea) to skin rashes/hives and even anaphylaxis.

The most common example is Eczema or iron deficiency related to cow’s milk allergy, Celiac disease. For a full complete list of examples, a chart can be found here.

  • Cell-Mediated

Cell-mediated reactions are less common, and symptoms take relatively longer to manifest, up to 48 or 72 hours after ingesting the food.

The most common example is allergic contact dermatitis.

Non-Immune Mediated

Non-immune mediated reactions are caused by other agents independent from the immune system, such as chemical contaminants in the food, like histamines.

There are five primary types depending on the causes


The body’s suboptimal metabolic function due to insufficient digestive enzymes may contribute to food intolerance. This can occur due to aging, an unhealthy diet, excessive alcohol consumption, or genetic predisposition.


It occurs when food interacts with a medication or other pharmaceuticals that you are taking. For example, grapefruit juice can interact with some cholesterol-lowering drugs and increase their levels in the blood. This can lead to serious side effects.

Other pharmacologic triggers include caffeine, amines, and monosodium glutamate (MSG).

Environmental Toxins

Toxins such as salmonella and E. coli, or even mundane things like pollen or dust, may trigger severe reactions in the body if they’re present in the food.


Certain preservatives and additives in processed foods, such as nitrates, sulfites, polysorbate 80, or saturated fats, can cause adverse food reactions.

Long-Term Inflammatory Dietary Pattern

The human gut can trigger pro-inflammatory or anti-inflammatory responses depending on the dietary pattern.

An inflammatory dietary pattern increases the severity of food reactions and intolerance if left unmanaged for long periods. 

How To Improve Immune-Mediated Reactions

When it comes to autoimmune reactions to food, the most important thing you can do is work on improving your immune system- and if you have a true allergy- avoid it. These are some of the most effective methods:

  1. Eat a healthy diet: A diet rich in fresh fruits and vegetables, proteins, and healthy fats can help improve your overall health and immunity.
  2. Get enough sleep: Sleep is essential for immune function. Make sure to get at least 7-8 hours of sleep every night.
  3. Monitor nutrient deficiencies- many nutrients like vitamin D, iron, vitamin C and zinc play key roles in our immune system’s proper functioning. Your doctor can run regular tests to look at some of these and working with a dietitian can help you with treating deficiencies and preventing them.
  4. Reduce stress or find healthy ways to manage it: Stress can negatively impact your immune system, causing an unwarranted immune response to food protein. Long term stress can also increase your risk of flares. Try to find ways to relax and de-stress daily.
  5. Exercise: Exercise can help improve your circulation and overall health. A moderate amount of exercise is the key here – too much exercise can be detrimental to your immune system.

The small therapeutic portions would only trigger minimal or zero reactions, while your immune system learns that the food isn’t a threat to the body. Eventually, you can build a tolerance to the food. 

By following these tips, you can help improve your immune system and reduce the likelihood of having adverse reactions to food.

How To Improve Non-Immune Mediated Adverse Food Reactions

Here are some things that you can do to improve your non-immune mediated reactions:

  1. Keep a food diary. This will help you identify which foods are triggering your reactions so that you may avoid them later.
  2. Avoid additives and preservatives like nitrites, carboxymethycellulose and polysorbate 80 that can trigger reactions and have been identified as inflammatory triggers for IBD.
  3. Eat a variety of healthy foods. This will help ensure you get the nutrients you need and reduce the chances of reacting to a particular food. Additionally, it would be best to consult a qualified dietitian to address any restrictive eating habits or food anxieties that may contribute to food intolerance.
  4. Talk to your doctor about allergy testing and remedies for increased intestinal permeability. If you have problems with food allergies, it’s essential to know what foods you can and can’t eat. 

Similarly, your healthcare provider (dietitian or doctor) can recommend the most effective treatment option to reduce intestinal permeability, which may contribute to your adverse food reactions. 

  1. Monitor and treat nutrient deficiencies. Nutrient deficiencies are common with IBD, especially in flares. Vitamin D for example plays a key role in keeping our gut barrier integrity, so a deficiency can affect intestinal permeability and play into food intolerances. 
  2. Use enzyme supplements if necessary. While you can increase enzyme-rich food in your diet, enzyme supplements can best address enzyme deficiencies that may cause food intolerance in your body.
  3. Adopt a microbiome-supportive diet pattern. Several studies have determined that a diet consisting of more plant-based foods and omega 3 rich fish, ensures your gut can generate sufficient anti-inflammatory responses whenever you face an adverse food reaction. However, this is a long-term strategy to be used with other remedies proposed by your doctor or dietitian.

These tips can help reduce the severity of your non-immune mediated adverse food reactions. However, reactions are different for everyone, and it would be best to consult a qualified dietitian or doctor to get the best advice for your unique case. Learn about our 1:1 nutrition coaching.

Food Sensitivity Tests To Avoid

Food sensitivity tests are not the most accurate way to measure food reactions and some of them are outright scams. We don’t suggest food sensitivity testing as there is a tendency for false positives. We do not recommend any of the following:

  1. The Cytotoxic Test: This test looks for antibodies in your blood that are supposed to indicate a reaction to certain foods. However, the test’s accuracy is not guaranteed.
  2. The ELISA Test: This test is similar to the cytotoxic test but uses a different method to measure antibody levels. Again, this test is inaccurate and can often give false-positive results.
  3. The ALCAT Test: This test measures how your immune system reacts to different foods. However, there is no scientific evidence that this test is accurate, and it’s costly.
  4. The Vega Test: This test measures electrical impulses in your body in response to different foods. There is no scientific evidence that this test is accurate, and it can be expensive.
  5. Hair Analysis: This test involves sending your hair sample to a lab to supposedly analyze it for mineral/vitamin content and sometimes food sensitivities. This can be an expensive test and is not necessary or accurate.

Given that most tests only confirm the presence of food protein, they can’t be relied upon for an accurate diagnosis. The best option is to consult a qualified dietitian who can make a more conclusive diagnosis. 

Final Thoughts

Adverse food reactions are serious, and it’s essential to have the correct facts. These reactions can be life-threatening; the sooner they’re treated, the better.

If left untreated, some adverse food reactions may worsen and contribute to more severe chronic issues like atopic dermatitis, gastrointestinal distress, etc.

We also encourage you to share this information with others. By spreading the word, we can help more people be aware of the signs and symptoms and get the treatment they need.

Ready to take charge of your nutrition and health? Contact us today to schedule an appointment with a qualified dietitian.

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