NutriCheck I Unverträglichkeits-Test: what does this mean exactly?

The NutriCheck I Intolerance Test is a direct-to-consumer (DTC) test that typically combines genetic markers (e.g., LCT for lactose intolerance, HLA-DQ for celiac disease) with IgG antibody measurements against foods. While the genetic tests for lactose intolerance and celiac disease have moderate evidence (human studies, GWAS), IgG-based 'intolerance tests' are not scientifically validated and are not recommended by medical societies (e.g., DGE, EAACI). IgG antibodies merely indicate immune exposure, not intolerance or allergy. The test often produces long lists of alleged intolerances, leading to unnecessary dietary restrictions. Overall evidence is mixed: the genetic components have some basis, but the IgG tests are marketing. Clinical confirmation (e.g., breath test for lactose, biopsy for celiac) remains the gold standard. Safety note: unsupervised elimination diets can cause nutritional deficiencies, especially in children.