warum vertrage ich keinen kaffee mehr — what does this mean exactly?

The question 'why can't I tolerate coffee anymore' points to a common but multifactorial issue. Coffee intolerance can stem from genetic variants in CYP1A2 (caffeine metabolism), changes in gut microbiome, increased gastric acid, anxiety, or interactions with medications. It may also reflect age-related changes in liver function or hormonal shifts. DNA tests can offer clues about caffeine metabolism speed, but they are not diagnostic. The evidence is mixed: mechanistic studies support CYP1A2 effects, but lifestyle and environmental factors often dominate. Symptoms like jitters, heartburn, or insomnia are more actionable than a genetic result alone. The exact meaning depends on the individual's symptoms and context. It does not necessarily indicate a serious condition; often a temporary reduction or switch to low-acid coffee helps. Consulting a doctor or trying a coffee break can clarify the cause.