Bloated tummy. Brain fog. A pounding head. If mysterious symptoms appear hours or even days after you eat certain foods, it’s time to ask: Do I have a food intolerance?
What is a food intolerance?
A food intolerance is trouble digesting a certain food. Food intolerances induce undesirable reactions to the trigger food, including:
- gastrointestinal symptoms
- respiratory symptoms
- itchy and runny nose
- watery eyes
Food intolerances may also play a role in irritable bowel syndrome, which is a chronic gastrointestinal disorder.
Unlike food allergies, which involve the immune system, food intolerances involve the digestive system. Allergic reactions are usually immediate and are brought on by even minute amounts of an allergen (see “Is it a food allergy?”), while reactions due to non-allergic intolerances can be delayed by up to several days and are often long-lasting. Some people who experience food intolerances have a threshold for the offending food and can eat it in small amounts; larger quantities or more frequent consumption of the food will bring about a reaction.
Is it a food allergy?
True food allergies trigger an immune system response and often involve immunoglobulin E (IgE), which are antibodies produced by the immune system. (Non-IgE-mediated allergies also exist but are less well understood.) In the case of an IgE-mediated food allergy, instead of fighting off invaders, IgE binds to benign substances like food proteins. These immune system triggers are known as allergens.
In children, 85 percent of food allergies involve cows’ milk, egg, fish, peanuts, shellfish, soy, or wheat. In adults, the most common allergens include peanuts, tree nuts, and seafood.
To be classified as an IgE-mediated response to a food, symptoms must occur within two hours of exposure. Exposure usually occurs through eating, but skin exposure or inhalation of food residue may also activate a response.
Allergen binding causes the release of inflammatory substances that promote recognizable allergy symptoms like skin reactions (hives, rash, and swelling)—the most common IgE-mediated food allergy symptoms—as well as gastrointestinal discomfort (nausea, vomiting, diarrhea, and abdominal pain), itching or tingling in the mouth, runny nose, and sneezing. Symptoms like difficulty breathing, rapid pulse, dizziness, or fainting may also occur. Note that with many of these symptoms, you could be having a severe reaction known as anaphylaxis and should seek emergency medical help immediately.
Unlike food intolerances, food allergies can be fatal. Due to the potential danger of allergy tests, they are typically performed in a specialized clinic.
Be proactive—not reactive—with key supplements
Since many sensitizing reactions begin in the gut, it may be helpful to support your gastrointestinal tract. Beneficial bacteria known as probiotics help to promote digestion and regulate the immune system and may reduce allergic responses.
These help you assimilate nutrients. The enzyme lactase, for example, helps with absorption of lactose.
Omega-3 fatty acids
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) help to modulate the immune system and are potentially allergy protective. Fish oil supplements are high in omega-3s; however, it’s unclear if people who have seafood allergies can safely take fish oil. Vegetarian omega-3 supplements may be a better option for them.
What causes a food intolerance?
There are many possible explanations for a food intolerance. Reactions could occur due to a deficiency in an enzyme required to break down the trigger food, which is what occurs in lactose (milk sugar) intolerance. With lactose intolerance, gastrointestinal responses are common and include bloating, cramps, diarrhea, and flatulence.
Fructose intolerance, on the other hand, involves the inability to absorb fructose (found in fruits and added to some foods as a sweetener), or it may be induced by an imbalance of fructose versus glucose in the intestines. Unabsorbed fructose ferments in the colon and leads to symptoms similar to those of lactose intolerance.
Meanwhile, non-celiac gluten sensitivity (NCGS) is a recognized condition associated with consumption of gluten, a protein found in wheat, rye, barley, and triticale. In affected people, eating gluten may cause severe gastrointestinal symptoms, as well as anemia, brain fog, chronic fatigue, depression, joint and muscle pain, numbness in extremities, weight loss, and changes in attention. In order to diagnose NCGS, both celiac disease (an autoimmune disease triggered by eating gluten) and wheat allergy must first be ruled out.
Overconsumption of a food or food additive can cause unpleasant consequences in some people. Naturally occurring chemicals and food additives that are linked with food intolerances include”
- amines (in beer, cheese, chocolate, wine, and yeast extracts)
- glutamates (in cheese, tomatoes, mushrooms, stock cubes, and yeast extracts)
- salicylates (in beer, nuts, wine, herbs and spices, jam, honey, yeast extracts, tea, and coffee)
- flavor enhancers like monosodium glutamate (MSG), artificial sweeteners and colorings, preservatives, and sulfites
In other instances of food intolerance, there is no explanation yet.
How is a food intolerance diagnosed?
Elimination diets may be the most effective—if most cumbersome—method of isolating a food culprit. Strictly avoid all suspect foods for at least two weeks to establish whether symptoms abate. Then, reintroduce one food at a time, spaced out over a few days, to determine if symptoms reappear.
Because avoiding a number of foods may restrict your nutrient intake, it’s best to work with a nutritionist or naturopath to ensure you don’t become deficient. Book an appointment and start keeping a food journal to track your symptoms and get a handle on possible trigger foods.