was ist kefir — when to see a doctor?

Kefir is a fermented milk drink made from kefir grains (a symbiotic culture of lactic acid bacteria and yeasts). It contains probiotics that may support gut health, along with vitamins and minerals. For healthy adults, kefir is generally safe. You should see a doctor if you experience persistent bloating, diarrhea, abdominal pain, or nausea after consumption. People with weakened immune systems, serious underlying conditions, or organ transplants should consult a physician before regular intake, as live cultures can rarely cause infections. Kefir is not recommended for infants under one year due to the risk of cow's milk allergy or infection. The evidence for health benefits is mostly based on observational studies and practical experience; effects vary individually. A positive DNA test for lactose intolerance (e.g., MCM6 variants) may indicate better tolerance of kefir than milk, but caution is still advised. When in doubt or if symptoms arise, consult a doctor.