warum vertrage ich plötzlich keinen kaffee mehr — what can you do yourself?

Sudden coffee intolerance can stem from changes in gut microbiome, stress, medications, or genetic variants like slow caffeine metabolism (CYP1A2). The ALDH2 gene mentioned in the context relates to alcohol, not coffee. Direct genetic testing for coffee tolerance lacks strong evidence. What you can do yourself: Keep a symptom diary (timing, amount, preparation), try decaf or switch roast (light roasts have more chlorogenic acid, which may irritate some stomachs). Check for additives like milk or sweeteners – lactose intolerance or FODMAPs could be triggers. Reduce to one cup daily and avoid drinking on an empty stomach. If symptoms persist (heartburn, diarrhea, palpitations), consult a doctor to rule out organic causes. Self-help measures are based on mechanistic reasoning and anecdotal experience, not large trials.