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

Sudden coffee intolerance can have multiple causes not directly covered in the provided knowledge base. Possible mechanisms include changes in caffeine metabolism (e.g., via CYP1A2 gene variants), increased stomach acid production, irritable bowel syndrome, or hormonal fluctuations (e.g., during menopause). Histamine intolerance or altered liver function may also contribute. The provided context contains no specific information on coffee or caffeine. Evidence for these links is mostly mechanistic or observational; there is no clear genetic or clinical guideline for sudden coffee intolerance. A DNA test for CYP1A2 might offer clues about caffeine metabolism, but sudden changes are often multifactorial and not purely genetic. Medical evaluation (e.g., gastroenterologist) is recommended if symptoms persist.