Have you ever wondered if you might be negatively reacting to something you ate? Many of my patients have reported feeling poorly after eating but have a difficult time pinpointing exactly what foods might be causing their symptoms. Adverse food reactions can be related to food allergies, sensitivities, or intolerances. The severity and onset of symptoms can vary.

Symptoms from adverse food reactions could include:

• Upset stomach
• Bloating
• Diarrhea
• Constipation
• Vomiting
• Stuffy nose/congestion
• Joint pain
• Migraines/headaches
• Fatigue
• Skin issues – rash, eczema, hives
• Wheezing, shortness of breath
• Swelling of the tongue or throat
• Anaphylaxis

Adverse food reactions can be immune-related or non-immune related.  Immune-related reactions are an allergy or a food sensitivity.  A non-immune related reaction is a food intolerance.

Food Allergies

The most severe type of adverse food reaction is an allergic reaction. The most common food allergies are: peanuts, tree nuts, fish, shellfish, cow’s milk, eggs, soy, and wheat. The American Academy of Allergy, Asthma, and Immunology defines an allergy as:

“…a chronic condition involving an abnormal reaction to an ordinarily harmless substance called an allergen. Allergens can include aeroallergens such as dust mites, mold, tree weed, and grass pollen, as well as food allergens such as milk, egg, soy, wheat, nut, or fish proteins.

If you have an allergy, your immune system views the allergen as an invader, and a chain reaction is initiated. White blood cells of the immune system produce IgE antibodies.

These antibodies attach themselves to special cells called mast cells, causing a release of potent chemicals such as histamine.

These chemicals cause symptoms such as: Itching in the nose, roof of the mouth, throat, eyes, Sneezing, Stuffy nose (congestion), Runny nose, Tearing eyes, Dark circles under the eyes, Food allergies may present with vomiting, diarrhea, respiratory symptoms or anaphylaxis immediately after ingestion of the culprit allergen.”

The key point to remember about Food Allergies is that they involve an immune response in which IgE antibodies are formed.

The IgE antibodies then attach to mast cells, which are a type of white blood cell (WBC) that lines tissues, such as the lungs, gut, or throat.  When a “trigger” food is ingested, IgE antibodies attach to the food antigen and present it to mast cells.  

The mast cells then react by degranulating and releasing proinflammatory chemicals called mediators (cytokines, interleukins, prostaglandins, histamine, etc). Mediators are what cause symptoms.

Think of IgE as the guy on watch duty. When IgE comes into contact with the enemy (trigger food), IgE sounds the alarm and the mast cells send out the troops to fight.

Degranulation of a mast cell is like sending out the troops to fight. And the troops are the proinflammatory mediators. So if mast cells in the skin react, a person might break out in hives. Or if mast cells in the lungs are triggered, a person will have trouble breathing or asthma.  

For more information on food allergies, The American College of Asthma, Allergies, and Immunology is a good resource.

Food Sensitivities

The other type of immune-related adverse food reaction is a Food Sensitivity. Food sensitivities occur when white blood cells react with a food and release mediators.  Food sensitivities do not involve IgE antibodies.  

When you eat a trigger food, it makes its way along your digestive tract to your small intestine, where that food comes into contact with your gut lining and immune system. Food particles pass from your gut into your bloodstream.  

In your bloodstream, WBC release mediators in response to exposure to the trigger food. The release of mediators from WBC is what causes inflammation and symptom manifestation, such as GI issues, headaches, joint pain, or body aches.

To read more about food sensitivities, check out this post.

Food Intolerances

Food intolerances occur when a person is lacking an enzyme to break down a food, such as lactose intolerance. This is a non-immune related response.  Symptoms of food intolerances usually present as GI issues – gas, bloating, and diarrhea.   Fructose malabsorption also falls into this category.