Is it food intolerance? Signs you shouldn’t ignore

Food intolerances, also known as food sensitivities, occur when the body has difficulty digesting certain foods or their components. One of the most common intolerances is lactose intolerance. A food intolerance can be very uncomfortable for those affected and is accompanied by a variety of symptoms such as bloating and/or diarrhea. In this blog, we take a closer look at various food intolerances, their typical symptoms, and conditions that should be differentiated from food intolerances.

Table of contents

• What is the difference between a food intolerance and a food allergy?
• Overview of the most common food intolerances
• What are the general symptoms of a food intolerance?
• What conditions should be differentiated from a food intolerance?
• How does a food intolerance develop?
• Summary

What is the difference between a food intolerance and a food allergy?

The main difference between a food intolerance and a food allergy lies in the reaction of the immune system to the food in question. The differences are explained in detail in the following table:

Source: Mayo Clinic, 2022; NHS, 2022; NHS, 2023

Overview of the most common food intolerances

Lactose intolerance: 

Lactose intolerance is a common digestive disorder in which the body does not produce enough of the enzyme lactase to fully break down the sugar lactose found in dairy products. People with lactose intolerance often experience symptoms such as bloating, abdominal pain, and diarrhea after consuming lactose-containing foods. Lactose-rich foods that frequently cause symptoms include cow's milk, yogurt, cream, and soft cheeses such as Camembert or Brie. It must be distinguished from a milk allergy, which can be life-threatening.

Source: John Hopkins University, 2024

Histamine intolerance:

Histamine intolerance refers to a reaction that occurs when the body has difficulty breaking down histamine. Histamine, a naturally occurring substance in our bodies and in certain foods, cannot be properly processed in affected individuals due to a deficiency or dysfunction of an enzyme. This intolerance manifests in symptoms not typically associated with other food intolerances, such as skin flushing, severe headaches, and migraine-like symptoms. Because of these symptoms, histamine intolerance is often classified as a pseudoallergy. A pseudoallergy causes reactions that resemble true allergic reactions — including rash, itching, respiratory symptoms, and gastrointestinal complaints — without the immune system being involved in the typical way of a true allergy. Histamine-rich foods that may trigger symptoms in people with histamine intolerance include:

• Aged cheeses
• Smoked meats
• Certain fish types
• Fermented products such as sauerkraut
• Vegetables (tomatoes, eggplants, and spinach)
• Alcoholic beverages, especially red wine

Source: Cleveland Clinic, 2023

Fructose malabsorption:

Fructose malabsorption is a digestive disorder in which the intestine has difficulty absorbing fructose — a sugar found in many fruits and vegetables (especially onions, artichokes, peas, asparagus) and honey. This leads to digestive complaints such as bloating, abdominal pain, diarrhea, and occasionally nausea, particularly after consuming fructose-containing foods. In contrast is hereditary fructose intolerance, a more severe, genetically determined metabolic disorder in which the intake of fructose not only causes digestive issues but can also lead to serious health problems such as liver damage. Therefore, fructose malabsorption is a food intolerance, whereas hereditary fructose intolerance is a specific metabolic disorder that goes beyond the scope of simple food intolerances. The term “intolerance” can therefore be misleading in the context of hereditary fructose intolerance.

Source:  Cleveland Clinic, 2021

Non-celiac gluten sensitivity (NCGS):

Gluten sensitivity, also known as non-celiac gluten sensitivity (NCGS), is a condition in which individuals who do not have celiac disease or a wheat allergy develop symptoms after consuming gluten-containing foods. Gluten is a protein found in wheat, rye, and barley. Symptoms of gluten sensitivity can be gastrointestinal in nature, such as bloating and abdominal pain, but also include systemic reactions like headaches, fatigue, and joint pain. Treatment is primarily based on a gluten-free diet, which leads to a significant improvement in symptoms for many affected individuals (Catassi et al., 2015).

Is celiac disease considered a food intolerance?

Celiac disease is not an ordinary food intolerance or sensitivity but rather an autoimmune disease triggered by a reaction to gluten. Unlike a food intolerance, where the body has trouble digesting or processing certain foods, in celiac disease the ingestion of gluten causes an immune response and inflammation that severely damages the small intestine. The term gluten intolerance is often used misleadingly, but as a collective term, it includes various conditions such as celiac disease, wheat allergy, and gluten sensitivity (NIDDK, 2020; MedlinePlus,2017).

Common symptoms of food intolerances

• Abdominal pain & cramps
• Diarrhea
• Nausea & vomiting
• Constipation
• Bloating & gas
• Fatigue

Source: Cleveland Clinic, 2021

Which conditions should be ruled out before diagnosing a food intolerance?

When diagnosing a food intolerance, it is important to rule out other conditions with similar symptoms, including food allergies, irritable bowel syndrome (IBS), celiac disease, inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis, as well as gastrointestinal infections. These conditions can cause similar symptoms but require different treatment approaches. If you are experiencing unclear or persistent symptoms, it is essential to seek medical advice.

Want to investigate your symptoms from home?

For those who would like to examine their symptoms more closely at home, Homed-IQ offers helpful options. In addition to the Allergy Test Extensive, which measures IgE reactivity to 295 different allergens, the Gut Inflammation Test can provide further insight and help clarify the cause of your symptoms.

How does a food intolerance develop?

The exact mechanisms that lead to food intolerances are complex and not yet fully understood. They can vary from person to person. The development of a food intolerance can be influenced by the following factors:

• Genetic predisposition: A genetic tendency can make some individuals more sensitive to specific foods or food components.
• Changes in the digestive system: Disruptions or changes in the digestive system, such as a lack of digestive enzymes or an imbalanced gut microbiota, can increase sensitivity to certain foods.
• Dietary habits: Frequent consumption of specific foods or a highly unbalanced diet may also increase the risk of developing food intolerances.
• Medical conditions: Certain medical conditions like irritable bowel syndrome (IBS) or celiac disease can contribute to the development of food intolerances.
• Leaky gut syndrome: A compromised gut barrier, also known as leaky gut syndrome, may allow undigested food particles to enter the bloodstream and trigger immune responses that cause intolerance symptoms.
• Food additives: Certain additives in food such as preservatives, colorants, or flavor enhancers can trigger intolerances in some individuals.

Source: NHS, 2022

Summary

Food intolerances, also known as food sensitivities, are digestive problems that occur when the body has difficulty properly digesting certain foods or their components—lactose intolerance being one of the most common forms. These intolerances lead to a variety of symptoms such as bloating, abdominal pain, and diarrhea, and differ from food allergies, which trigger an immune response. It is crucial to rule out other conditions with similar symptoms in order to achieve an accurate diagnosis and enable targeted treatment for food intolerances.