NutriCheck I Unverträglichkeits-Test: what are common causes?

The NutriCheck I Intolerance Test is a commercial product that claims to identify food intolerances based on DNA markers. However, the most common causes of genuine intolerances are not purely genetic: lactose intolerance (LCT gene, lactase deficiency), fructose malabsorption (GLUT5 transporter), histamine intolerance (DAO deficiency), or non-celiac gluten sensitivity. These conditions are often triggered by enzyme deficiencies, gut microbiome alterations, or irritable bowel syndrome – not by single gene variants. DNA tests for intolerances generally have weak evidence: they often show only small risk increases that are barely relevant in daily life. Moreover, many claimed markers are not supported by independent studies. A positive result does not necessarily mean a clinical intolerance. The German Nutrition Society recommends medical evaluation with elimination diet and provocation test if an intolerance is suspected. The NutriCheck I can at best serve as a rough orientation but does not replace medical diagnostics. Be cautious of exaggerated promises: most intolerances are multifactorial and cannot be read from DNA alone.