What is food intolerance?

Have you ever noticed that when you eat a certain food, such as tuna, blueberries, avocado, asparagus or broccoli, that you get extremely bloated to the point that you are extremely uncomfortable? Since the foods I mentioned are celebrated for their many nutritional benefits, it might not occur to you that you most likely have an intolerance to that food. Up to 80% of the U.S. population has some form of food intolerance.

Most people are aware of food allergies, but food intolerance is a different phenomenon which can have a tremendous effect on a person’s quality of life. Food allergies appear quite suddenly, from seconds to minutes after ingestion of the offending food, and can be life-threatening, whereas food intolerance is a more gradual process (taking hours to a couple of days for symptoms to emerge), not life-threatening, and may only occur after a large amount of the food is eaten. Food allergies and food intolerance can both cause similar symptoms, such as abdominal pain, nausea, and diarrhea, but food intolerance is notorious for causing bloating, heartburn, irritability, headaches and general malaise. The most common food allergy triggers are peanuts, tree nuts, shellfish, fish, soy, wheat, milk and eggs, while the foods most commonly associated with food intolerance are dairy products, gluten-containing grains, eggs, citrus, beans, cabbage, and broccoli.

People who are allergic to certain foods know that even a small amount of the food can trigger an allergic response, and the response occurs every single time the person is exposed. The immune system reacts to the food by causing a release of IgE antibodies, which then cause a release of histamines and cytokines designed to attack the offending agent. Sometimes the entire body is affected by this response, and symptoms such as shortness of breath, hives, rash, or a sudden drop in blood pressure can occur. Food intolerance, in contrast, is more insidious, and may only occur if a large amount of the triggering food is eaten or if it is consumed frequently. Trigger foods will cause a rise in IgA, IgG, and IgM antibodies, causing the body to mount a delayed reaction which is characterized by mostly gastrointestinal symptoms, but which can cause other symptoms as well. Regardless of how the body reacts, the discomfort caused by poor digestion of the food can be enough to make the sufferer miserable.

Why does food intolerance occur? There are several explanations. One cause is enzyme deficiency. All enzymes are specific to one type of molecule, such as lipases which break down fats. Sometimes an individual can be deficient or completely lacking in a very specific enzyme which is required for digestion of a particular food. A common example is found in lactose intolerant individuals who do not have enough lactase to break down the milk sugars into their constituent parts for absorption in the intestine. The lactose cannot be broken down so it sits in the intestine, causing bloating, spasm and diarrhea when it sits in the digestive tract. Approximately 25% of the U.S. population suffers from lactose intolerance, which amounts to a lot of bloated bellies from the consumption of dairy products.

Another common type of food intolerance is to gluten. Gluten is highly resistant to digestion as it is, and in some individuals, the gluten cannot be broken down at all. The problem with gluten is that it is found in wheat, rye, barley, spelt and kamut, so avoiding gluten can be challenging to say the least. Approximately 1% of the U.S. population has celiac disease, while about 15% have gluten intolerance. Regardless of whether someone has celiac disease or gluten intolerance, ALL gluten must be avoided. However, if there are occasions in which completely avoiding gluten is impossible, digestive enzymes, specifically DPP-IV, can help individuals to digest meals containing gluten.

The list of substances which people may have an intolerance to doesn’t stop there. Some individuals cannot break down phenols, including salicylates, due to insufficient amounts of xylanase, and suffer from behavioral and learning disorders, including ADHD and autism. Some individuals are unable to break down disaccharides, an intolerance which is closely linked to irritable bowel disease, ulcerative colitis, Candida overgrowth and autism. As if all that wasn’t enough to worry about, there are chemical substances in foods which can spark intolerance, such as caffeine, aflatoxins in undercooked beans, amines in cheeses, artificial colorings and flavorings, preservatives, sweeteners, emulsifiers, nitrates, MSG, sulfites and salicylates. Salicylate intolerance can cause a susceptible individual to react to large amounts of salicylate-containing foods, particularly citrus fruits, teas, mint flavoring, berries and processed foods with flavor additives.

The digestive tract regularly takes the brunt of foods, medications, hormones, and chemical additives which can interfere with repair of the gut lining, causing increased intestinal permeability which is more commonly known as leaky gut. Leaky gut is characterized by the loosening of tight junctions between the cells which line the gut, thus allowing food molecules to pass through. These free floating food molecules are viewed by the immune system as a threat and will mount an immune response which manifests as the signs and symptoms of food intolerance. Think of all that food sitting in the gut, undigested. Pretty unnerving, huh?

How to diagnose food intolerance

Diagnosing food intolerance can be extremely difficult since the signs and symptoms often mimic those of food allergy. One method of ferreting out which foods are involved in a food intolerance is keeping a food diary in which all foods eaten are recorded, along with symptoms and their time of onset. After suspected trigger foods have been determined, an exclusion diet can be implemented, in which those foods are removed from the diet for weeks to months. If the symptoms disappear during the exclusion phase, potential trigger foods can be re-introduced after this phase is completed in order to determine which substances are problematic. If the food intolerance is mild, a small amount of the food will not trigger symptoms, and in many cases may still be consumed, especially if enzymes are taken to aid in digestion. Essentially, many people can return to foods which they were mildly or even moderately intolerant of after avoiding it for a period of time.

Blood testing is considered the most reliable and comprehensive form of testing for food intolerance, but there are only a few laboratories which specialize in this type of test. ALCAT, Pinnertest.com and HEMOCODE Food Intolerance System are laboratories which offer food intolerance testing via serum analysis, with ALCAT considered the largest food intolerance testing group in the U.S. Some insurance plans will cover part or all of the expense of the testing, so it is always worth inquiring about insurance coverage. Some testing panels also provide a detailed rotation diet which patients can follow when they are ready to reintroduce the foods of which they are intolerant.