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Digestive Disorders > Intolerances

Food Intolerances: 5 Essential Questions

Dr. med. André Sommer

Dr. med. André Sommer

We’ve all been there: You have something to eat, and then your stomach starts to twitch and rumble. Greasy food or large amounts weigh heavily on your stomach every time. Bloating can also lead to uncomfortable abdominal pain. Once the air has escaped, things usually get better quickly.

If your digestive tract starts acting up regularly after eating, a food intolerance could be the cause. Various intestinal reactions to food are grouped under the heading of food intolerances. Intolerances to certain foods can also occur in the context of diseases such as irritable bowel syndrome.

What are the symptoms of food intolerance?

The symptoms associated with food intolerance are very diverse:

  • ** Acute stomach pain**
  • Nausea
  • Vomiting
  • Stool irregularities, especially diarrhea
  • Flatulence and bloated stomach (flatulence and meteorism)
  • Urgency

Stool irregularities and abdominal pain can have many causes. With food intolerances, the consumption of certain foods triggers the unpleasant gastrointestinal symptoms. This means that the symptoms always appear after eating. Symptoms often improve after a bowel movement and when food is avoided.

When should I go to the doctor?

**Chronic **indigestion over three months with diarrhea and abdominal pain should always be clarified with a doctor. Stool changes should also be examined. First of all, you should report your symptoms to your family doctor. Together you discuss how to proceed.

In certain cases, extensive diagnosis by a gastroenterologist is necessary. If a food intolerance is suspected, the gastroenterologist performs an H2 breath test. Indigestion caused by food intolerance is harmless but stressful.

Do you suspect you have a food intolerance? Many people often do without certain foods for no reason! So it makes sense to find out which foods trigger digestive problems with a detailed food and symptom diary: our digestive health app can help!


Bloody diarrhea or weight loss are always a warning sign! If these occur, you should consult a doctor and undergo a gastroenterological examination.

What types of food intolerances are there?

The terms food intolerance, nutritional intolerance and food allergy are often used interchangeably. However, this is not correct. All reactions of the body to food are categorised as food intolerance. However, these reactions arise in different ways - that is, they have a different pathomechanism. A distinction is made between the following:

  • Food allergy: allergic reaction of the immune system
  • Food intolerance: disturbed splitting or absorption of food components
  • Celiac disease: autoimmune disease (inflammatory reaction with autoantibodies)

Food allergies

With a food allergy, a reaction of the immune system leads to gastrointestinal symptoms. With this disease, the immune system is hypersensitive to actually harmless substances: It forms antibodies against the food proteins. An allergic reaction (anaphylactic reaction) occurs. Therefore, in addition to the typical gastrointestinal complaints, symptoms such as rash and itching also appear with a food allergy.

Mucous membranes in the head and neck area can also swell. This is what makes the disease so dangerous: If the throat swells, the reaction due to shortness of breath can become life-threatening. In severe cases, circulatory problems up to allergic shock can occur. That is why the food must be avoided completely if you have a food allergy. Typical triggers for food allergies are:

  • Cow’s milk
  • Chicken eggs
  • Wheat
  • Soy
  • Nuts
  • Peanuts
  • Fish and crustaceans

Food allergies rarely arise in adulthood. Children are more often affected. They react primarily to the protein in cow's milk, wheat, soy or chicken eggs. Generally the allergy subsides by adulthood. However, nut and fish allergies tend to persist. Allergy sufferers should always have an emergency **allergy kit **with them.

What does an emergency allergy kit include?

An emergency kit contains antihistamines, cortisone and an adrenaline injection (EpiPen). In the event of a severe attack with shortness of breath and circulatory failure, you must react quickly and immediately take the medication in the emergency kit. Then call for help. Because the physical reactions can be life-threatening.

Food intolerances

If someone has a food intolerance, food components cannot be broken down either due to an enzyme deficiency or an enzyme defect (maldigestion) or because the transporter for the absorption of the nutrient is defective or not present in sufficient quantity (malabsorption).

If lactose is not broken down into its glucose and galactose components, or if fructose is not fully absorbed, symptoms will arise. The sugars get into the large intestine and are metabolized there by the local bacteria. The fermentation process creates gases and thus uncomfortable bloating and cramps. The sugars also cause more water to flow into the colon, resulting in diarrhea. The formation of lactic acid and acetic acid during fermentation by the bacteria accelerates intestinal motility.

  • **Lactose intolerance **due to lactase deficiency
  • **Histamine intolerance **due to lack of diamine oxidase
  • **Fructose intolerance **due to overloading Glut-5 transporter
  • Hereditary fructose intolerance (very rare hereditary enzyme deficiency)
  • Lectin (in wheat, soybeans and nightshade family)
  • Sorbitol
  • Wheat sensitivity
  • Salicylate intolerance
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How are food intolerances tested?

Due to the incomplete digestion and absorption of lactose and fructose, the fermentation process of the bacteria produces hydrogen (H2). This can be determined by analyzing the breath. You can find out exactly how the H2 breath test works in our specialist article. Many gastroenterologists offer the test. It serves to determine or to exclude the lactase deficiency or the fructose intolerance.

Some doctors and naturopaths offer a blood test to detect food allergies. These are not recommended. On the one hand, food allergies are very rare and can be recognized very clearly by their symptoms. The number of **IgG antibodies **is also measured. It is quite normal for the body to have IgG antibodies to food. Therefore, this type of testing is very controversial - and expensive because health insurance does not pay for it. In addition, the result often leads to unnecessary omission of many foods.

Since special and individual food intolerances cannot be found out by a blood test, a symptom diary helps. This method is more complex, but it reliably finds out which foods you can tolerate. Through an omission diet and subsequent test phase, you can find out your individual tolerance limit for each food.

**Beware of blood tests**

Blood tests for the detection of food allergies are not recommended. An allergy can usually be clearly interpreted by its symptoms. This usually makes an expensive blood test superfluous.

Is there a self test for food intolerance?

Do you suspect food intolerance? If you are already paying attention to your diet, you can use our food intolerance self-test to help find out which foods could be responsible for your indigestion. The result gives an indication, but does not replace a medical examination for severe symptoms.

Somogyi, J.C., Mueller, H.R. and Ockhuizen, T., 1991. Food allergy and food intolerance: nutritional aspects and development. Downloaded on 10/10/2018 from:

Vogelreuter, A. (2012). Nahrungsmittel-unverträglichkeiten. Wissenschaftliche Verlagsgesellschaft Stuttgart. Downloaded on 10/10/2018 from:

Dr. med. André Sommer

Dr. med. André Sommer

I’m André, a medical doctor from Berlin. Together with a team of medical doctors, nutritionists and data scientists we empower people to understand digestive issues with our app Cara Care.

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