Gluten, also known as gliadin, is the gluten protein in most cereals. We must distinguish between two forms of gluten intolerance:
Coeliac condition
This is a real gluten allergy in which the small intestinal villi degenerate and a maldigestion and malabsorption syndrome develops. Diarrhoea, loss of minerals and weight loss are the consequences. In celiac disease, cereals containing gluten should never be eaten. Celiac disease can be detected by determining endomysial antibodies, gliadin antibodies and a small intestine suction biopsy.
Gluten intolerance with an IgG4 immune response
This is an excessive immune response to gluten. The resulting complaints can be manifold and very unspecific. This intolerance often manifests itself in unclear pain in the musculoskeletal system, fatigue and susceptibility to infections. This intolerance is proven by an IgG4 blood test. The consequence is also the avoidance of gluten, whereby however small quantities do not fall so much into the weight.
Nutrition for gluten intolerance
Since gluten generally irritates the intestinal mucosa, it should be avoided with colon irritable and other intestinal inflammations. Our cereals have been bred to contain more and more gluten, as the flour is then better suited for baking. So today we are burdened with a quite high dose of gluten.
Gluten-free cereals or cereal substitutes:

Rice
Maize
Millet
Quinoa
Amaranth
Teff
Buckwheat (not really cereal)