warum vertrage ich keinen kaffee mehr — what symptoms are typical?

The question of why you can no longer tolerate coffee is multifaceted. Typical symptoms of caffeine intolerance include nervousness, palpitations, insomnia, gastrointestinal upset, and headaches. Genetic variants in CYP1A2 (caffeine metabolism) and ADORA2A (adenosine receptor) can increase sensitivity. Slow metabolizers of caffeine experience prolonged effects. Age, liver function, pregnancy, and medications (e.g., oral contraceptives, antibiotics) can also reduce tolerance. The provided context does not contain direct studies on coffee intolerance; evidence is mechanistic and based on general pharmacogenetics. MyBody-X may test relevant genes, but effect sizes are moderate. A caffeine elimination diet or switching to decaf can help. Persistent symptoms warrant medical evaluation to rule out conditions like GERD, gastritis, or anxiety disorders.