Gluten-free diet

If you're following a gluten-free diet, you can't eat the following cereals or any foods or drinks made from them:

• Wheat, including durum and common wheat, and kamut/khorasan wheat
• Cereals that belong to the wheat family or crosses of these grains, such as
  • Spelt (also known as dinkel wheat), including a dried, unripe form ("Grünkern")
  • Ancient grains like emmer and einkorn
  • Triticale, a cross between durum wheat and rye
  • Tritordeum, a cross between durum wheat and wild barley
• Rye
• Barley
• Commercial oats (due to possible contamination with gluten-containing cereals), unless labeled "gluten-free"

Food producers must put labels on their packaging to show whether the food includes gluten-containing cereals or substances made from them. Some wheat-based ingredients in foods are harmless. But manufacturers still sometimes list the gluten-containing substances that these harmless ingredients are made from on the food label if they use them. That can be unsettling. These harmless substances include:

• Wheat-based glucose syrup, including dextrose and maltodextrin
• Barley-based glucose syrup
• Cereals used to make distilled products, such as ethanol for spirits and other alcoholic drinks

The following cereals and pseudo-cereals (grains that can be used like cereals), tubers, nuts and fruits are gluten-free. Some of them are mainly used to make plant-based flours. They are harmless for people with celiac disease as long as they are not contaminated:

• Oats
• Millet/teff
• Corn
• Rice and wild rice
• Amaranth
• Buckwheat
• Quinoa
• Hemp
• Pulses
• Soy
• Lupins
• Tiger nuts
• Potatoes/potato starch
• Cassava/tapioca
• Chestnuts
• Plantains (cooking bananas)
• Coconuts
• Nuts
• Linseed
• Chia seeds
• Grape seeds

Many other foods are naturally gluten-free as long as they have not been processed and potentially contaminated. These include the following:

• Meat
• Fish
• Milk
• Eggs
• Fruit
• Vegetables

Processed products that are labeled “gluten-free” can also be eaten without any concern.

A food is classified as being gluten-free if it contains a maximum of 20 mg of gluten per 1 kg. In Europe, products that have the European symbol of a crossed-out ear of wheat are the safest. They are below the limit of 20 mg/kg and are strictly monitored.

Sometimes, food products have contradictory information on their label or it's not clear whether the product might be contaminated with gluten. In Germany, unclear information on products and packaging can be reported to the German consumer advice center (Verbraucherzentrale) through their "Lebensmittelklarheit" website. Every reported case is checked and then published after contact with the manufacturer. The food label of the product might be changed as a result.

Along with eating foods made from millet, quinoa and amaranth, eating oat-based foods can be a particularly helpful way to make sure you get enough nutrients and fiber. But it's important to be sure that the oats didn’t come into contact with gluten-containing cereals when processed (known as cross-contact). Some gluten-free oat products are labeled as such and available in stores.

While a number of research studies found that oats even improved celiac disease symptoms, other studies found that a small group of people had an intolerance to oats. The German society for celiac disease (Deutsche Zöliakie Gesellschaft) recommends introducing oats into your diet once you have already successfully changed to a gluten-free diet and your symptoms have gone away or improved a lot. You can then gradually increase the amount of oats you eat.

Rice is very rich in nutrients but may be contaminated with harmful substances, including heavy metals such as arsenic, lead, cadmium and mercury. Eating a lot of rice can lead to higher concentrations of heavy metals in the body. For this reason, the German Federal Institute for Risk Assessment (BfR) recommends eating only moderate amounts of products such as puffed rice cakes, rice flakes and rice porridge. Babies and toddlers should not be given only rice-based drinks or rice porridge.

When choosing gluten-free alternatives, it's generally important to make sure you have a balanced diet with varied meals.

Nutritional therapy is usually a good idea if you have been diagnosed with celiac disease. It can help you to change your eating habits and still have a balanced diet. Ideally, a gluten-free diet should be varied and include enough of the nutrients that you need. Keeping a "food and symptom diary" can make it easier to keep track of your personal preferences and needs, and help you change your diet.

The advice given as part of the nutritional therapy

• helps you to identify and avoid foods that contain gluten when shopping.
• includes tips on how to store gluten-free foods in a way that prevents contamination. This is especially important if you live with other people who don’t have to avoid gluten.
• provides information about the possible side effects of a gluten-free diet. For instance, specially manufactured gluten-free products often have more calories and less fiber in them than gluten-containing alternatives do.

In certain phases (such as puberty or in difficult life situations) people might stop paying so much attention to their diet. It can then help to discuss your eating habits again with a nutritional therapist or dietitian. When young adults in Germany leave their pediatrician and switch to a family doctor or gastroenterology practice, that can also be a good time to seek professional dietary advice again.

Digestive problems often already start to get better a few weeks after switching to a gluten-free diet. Blood tests for antibodies against an enzyme in the body called tissue transglutaminase (tTG or TG2) can show whether the change in diet is helping. Without gluten, the immune system reaction stops, the antibodies are no longer made, and the inflammation goes away. It can take up to six months for the lining of the intestine to recover from moderate damage, and two to three years to recover from more severe damage. You will usually have blood tests every six months until then. The inflammation may go away more quickly in children.

In certain situations, doctors might suggest doing a gastroscopy to take samples of the lining of the intestine – but only if the symptoms don't go away, they come back, or the blood levels are still high despite following a gluten-free diet. It can take several months or even a few years for the lining to recover in adults, though. For this reason, doctors usually wait one to three years after you change your diet before suggesting that you have another gastroscopy, if needed.

Sometimes, blood tests and tissue samples show that the lining of the intestine still hasn't recovered, even after switching to a gluten-free diet. That is often because people eat foods with “hidden” gluten in them. Less strict phases or short breaks in gluten-free diets can also lead to new inflammation. Professional dietary advice can help you to identify sources of hidden gluten and find more practical ways to avoid gluten in everyday life.

In most people with celiac disease, the levels of antibodies in their blood go up and down in the first five years after switching to a gluten-free diet – especially at first. Over time, it becomes easier to select the right foods and stick to the new diet. So people who have been following a gluten-free diet for a while rarely still have high antibody levels.

But in a very small group of people with celiac disease (fewer than 1 to 2%), following a gluten-free diet doesn't help. This is known as “refractory celiac disease.” There are two types, depending on whether and how much the T-cells in the lining of the intestine have changed: Type I can usually be treated successfully. Type II is very rare. But about half of the people with this type tend to develop difficult-to-treat cancer within a few years. Because of this, it's important to have regular check-ups to detect any signs of cancer as early as possible.

People who follow a strictly gluten-free diet might put on weight at first. That is particularly likely if you eat a lot of gluten-free convenience foods: These often contain more sugar, fat, and calories than "normal" convenience foods. The manufacturers do that to make up for the fact that gluten-free products are slightly drier. Also, when people follow a gluten-free diet, their body is able to absorb enough nutrients and energy again, and balance out deficiencies.

Because gluten-free food products often don’t contain much fiber, they're not as filling either. So people often eat more to feel full. A lack of fiber can cause constipation, too.

Due to the effects of celiac disease, many people already have nutrient deficiencies when they change their diet. An unbalanced gluten-free diet can make these deficiencies worse. To prevent that, it's important to eat enough foods with vitamins, minerals and fiber in them. Then you can be sure you're getting enough nutrients like vitamin B12, folic acid, iron, zinc, magnesium and calcium. Examples of high-fiber foods include various seeds, wholegrain cereals and oats, pulses, a wide variety of vegetables (especially when eaten raw), nuts, dried fruits and many different types of fresh fruits.

To make sure you get a balanced diet and don't put on unwanted weight, it's a good idea to eat fresh foods such as vegetables, salads and fruits. Low-fat dairy products are also well suited and contain calcium, which is important for your bone health. You can get iron in your diet by eating things like lean meats, fish and seafood. If the lining of your intestine is so badly damaged that it can no longer absorb enough nutrients, your doctor can prescribe dietary supplements for you to take as well.