Studies have shown food intolerances affect approximately 20% of the population in industrialized countries, but despite their high prevalence, their exact mechanisms are unknown. Adverse food reactions include food allergies and food intolerances. Unlike food allergies that are characterized by immunological (immunoglobulin E (IgE)) dependent mechanisms, food intolerance is a non-immunological response to food or food components that leads to complaints like abdominal pain, diarrhea, hives, vomiting and eczema.

Whether it is gluten, FODMAPS or histamine, experts are reviewing the data currently available on common food intolerances and digestive and non-digestive disorders in a recently published article in Nutrients.

FODMAP sensitivity

FODMAPs include a variety of carbohydrates (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) that are difficult to absorb from the small intestine, resulting in gastrointestinal issues such as bloating, flatulence and even pain. A low FODMAP diet is the recommended diet for patients diagnosed with irritable bowel syndrome (IBS) and should be followed under the guidance of a dietitian to ensure compliance and to prevent nutrient deficiencies In this diet, high FODMAP foods are restricted initially and then slowly reintroduced.

Studies have shown this diet improves digestive symptoms such as diarrhea, flatulence and bloating in 50 to 80% of irritable bowel syndrome (IBS) patients. However, caution should be taken when following this restrictive diet over an extended period. Although the number of studies on long term consequences is limited, it has been shown that following a low FODMAP diet for just four weeks can decrease the amount of beneficial bacteria.

Gluten intolerance or sensitivity: How to find it?

Gluten is made up of several proteins found in grains such as wheat, rye and barley that are found in the composition of pasta, bread, pastries and many other processed foods.  Gluten intolerance has now been called non-celiac gluten sensitivity and is not allergy or the autoimmune disease celiac. It has been shown to cause a wide range of symptoms such as abdominal pain, bloating, headaches, leg or arm numbness, fatigue and skin issues.

Unfortunately, non-celiac gluten sensitivity is difficult to diagnose and the exact causes are unknown. However, following a strict gluten free diet followed by a gluten challenge could help determine if an individual suffers from non-celiac gluten sensitivity.

Histamine intolerance

Histamine is not only a compound produced by our immune system and involved in allergic reactions, but is also a food component naturally found in high amounts in fermented vegetable products (such as pickles), aged cheese and cured and fermented meats, as well as foods that are not fresh and have been stored such as leftovers and canned foods. Histamine intolerance occurs as a result of overproduction of histamine in the body or the inability to break it down, resulting in symptoms such as nausea, abdominal pain, tachycardia, headaches, and skin flushing. There is currently no clear diagnostic tool for histamine intolerance, and restricting histamine consumption for 4 to 6 weeks is the first line of treatment.

Although several foods or food components clearly cause food intolerances, studies are needed to fully understand the mechanisms behind the reaction, diagnosis and treatment. Following an elimination diet under the guidance of a dietitian is recommended, to ensure better patient compliance, education, aiding with re-introduction of specific foods and analyzing symptoms.

Analyzing and targeting the gut microbiome via probiotic administration or specific dietary changes allow clinicians and dietitians to better predict patient outcomes and develop personalized nutritional approaches in the future.



Tuck CJ, Biesiekierski JR, Schmid-Grendelmeier P, Pohl D. Food intolerances. Nutrients. 2019; 11(7). doi: 10.3390/nu11071684.