Understanding Gluten Intolerance – Symptoms, Causes & Gluten-Free Diet

What is gluten? And why does the body react to it?

Gluten refers to a protein found in many types of grains, especially in wheat, rye, barley, and related grains. This protein makes dough from bread and pasta elastic, for example. For most people, gluten is not a problem—the digestive tract can process it well. However, in some people, the body reacts sensitively to gluten or other components of these grains, leading to discomfort after eating.

Sometimes in everyday life, people generally speak of Gluten intolerance, in which various medically different reactions are summarized. They differ not only in cause but also in diagnosis and consequences for everyday life.

Gluten intolerance, celiac disease, or wheat sensitivity? The most important differences

Celiac disease

Celiac disease is the best-known and most well-researched form of gluten intolerance. It is a autoimmune disease. The immune system mistakenly recognizes gluten as a threat and attacks not only the protein itself but also mistakenly parts of the body – specifically the lining of the small intestine. This damage to the intestinal wall prevents the body from properly absorbing nutrients.

In celiac disease, it's enough already small amounts of gluten, to trigger this process. Some affected individuals immediately experience symptoms such as stomach pain, diarrhea, or bloating, while others initially have more nonspecific symptoms, such as fatigue or iron deficiency. Even if no acute symptoms are noticeable, the damage in the intestine can progress if gluten continues to be consumed. A gluten-free diet is not a temporary diet, but the only effective treatment.

The diagnosis is made through medical tests, including specific blood tests for gluten antibodies and often a tissue sample from the small intestine. Until this clarification process is completed, gluten should not be omitted, as this can distort the test results.

Wheat allergy

With wheat allergy, the immune system reacts to proteins in wheat. This reaction is a classic allergy, comparable to a pollen or nut allergy, it can manifest locally in the gastrointestinal tract, but also trigger skin reactions or respiratory problems. Unlike in celiac disease, the immune system does not target the body's own structures here, but only the foreign proteins.

The symptoms can occur immediately after consumption. The diagnosis is carried out allergologically, for example with skin or blood tests. Here, the aim is specifically to avoid wheat and wheat-containing products.

Non-celiac gluten sensitivity

A third form is the so-called non-celiac gluten sensitivity. This means the symptoms that appear are typical for a gluten reaction, but neither support the diagnosis of celiac disease nor an allergy. The causes are not yet fully scientifically understood. It is now being discussed that other components of the wheats or fermentable carbohydrates (FODMAPs) could trigger symptoms.

The symptoms of this sensitivity are similar to those of celiac disease: abdominal pain, bloating, diarrhea or constipation, but also fatigue, concentration problems, or headaches may occur. Many people feel better after eliminating gluten-containing foods. However, because no simple test exists, diagnosis is a process of elimination: Only when celiac disease and allergies are ruled out and symptoms improve on a gluten-free diet do doctors refer to this form.

Typical symptoms with gluten intolerance

Symptoms that can occur in connection with gluten are diverse. In the digestive tract, often flatulence, stomach pain, diarrhea, or constipation. These usually appear a few hours after eating and affect general well-being.

Many people also experience symptoms that are not directly related to the gastrointestinal tract. These include nonspecific symptoms like fatigue, headaches, or concentration problems, which may become stronger after a meal with gluten-containing foods.

So if you repeatedly complain of similar issues after consuming bread, pasta, pizza, or baked goods, this may be an indication that gluten plays a role.

From when should one see a doctor if suspected of gluten intolerance?

If you regularly experience discomfort after eating, it is worth getting a medical examination. It's best to start by documenting your symptoms accurately, noting when they occur and what you have eaten. This helps the specialists narrow down possible causes.

Diagnosis: Gluten intolerance – what now?

For people who have been diagnosed with gluten intolerance, the only therapy is to change their diet and avoid gluten-containing or wheat-containing products. Only then can the body regenerate, and the symptoms subside. But which foods contain gluten, and which can be eaten with gluten intolerance?

Gluten-containing foods – a list

Anyone suffering from gluten intolerance or sensitivity should avoid the following gluten-containing grains and foods:

• Wheat: Bread, pasta, cake, and cookies with wheat flour, wheat bran, or breakfast cereals. Udon noodles, couscous, or bulgur are also based on wheat.

• Barley: Beer is also made from barley and should be avoided in case of gluten intolerance. However, there are special gluten-free beers that are either made from naturally gluten-free raw materials (millet, rice, corn, buckwheat) or where the gluten has been enzymatically removed.

• Rye

• Spelt: Green spelt also contains gluten as a grain of spelt.

• Seitan: This is made from wheat gluten or wheat flour.

• Ancient grain: This includes, among others, Kamut or Emmer.

Gluten-free diet: Which foods do not contain gluten?

A gluten-free diet is based on natural foods like fruits, vegetables, potatoes, rice, corn, quinoa, amaranth, millet, buckwheat, as well as fresh meat, fish, eggs, legumes, nuts, seeds, pure dairy products, and oils. Coffee, tea, juices, wine, and clear spirits are also mostly gluten-free.

Gluten-free alternatives to traditional grains are, for example, rice, corn, or millet. Also pseudo-grains like quinoa or buckwheat are naturally gluten-free and can be consumed without problems.

Naturally gluten-free foods

• Grains & Pseudocereals: Rice, Corn, Millet, Buckwheat, Quinoa, Amaranth, Teff.

• Fruits & Vegetables: All types of fresh fruits and vegetables are gluten-free.

• Legumes: Lentils, beans, chickpeas, peas.

• Proteins: Fresh meat, poultry, fish, seafood, eggs (without breading).

• Dairy products: Milk, natural yogurt, quark, cheese (natural).

• Nuts & Seeds: Almonds, sunflower seeds, pumpkin seeds, flaxseeds (natural).

• Fats & Oils: Plant oils (olive, rapeseed, coconut), butter, lard.

• Sweeteners & Spices: Sugar, honey, pure spices, salt, pepper.

Gluten-free alternatives & ready-made products

• Flour & Baked Goods: Special gluten-free flours (e.g. from rice, corn, buckwheat), gluten-free breads, noodles or waffles.

• Sauces & Ready-made products: Only if explicitly labeled as "gluten-free."

When shopping and cooking, it is important to read ingredient lists and watch out for hidden sources of gluten, for example in sauces, soups, or spice mixes. Many products carry a special gluten-free symbol (crossed-out spike), which makes orientation easier.

Important: For people without a diagnosed intolerance a gluten-free diet has no proven health benefits and can, on the contrary, lead to nutrient deficiencies if balance is not maintained.

Conclusion:

Complaints after eating can have many causes, and gluten is just one of them. It is important to observe symptoms over a longer period of time and to have them professionally clarified. If gluten intolerance or sensitivity has been found, a gluten-free diet is the only but effective measure.

You have fewer problems after consuming grain-based products, but still constantly have intestinal problems? Read here to find out what else might be behind your irritated bowels.