Fermented milk carrying a broad mix of live bacteria and yeasts. Its most consistent measured effect is better blood sugar handling, concentrated in people who already have metabolic problems. Milk sugar tolerance and clearance of a common stomach bacterium rest on single trials. Cholesterol, blood pressure and inflammation results are mixed, with plain milk often matching kefir. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Fasting glucose | 75–86 mg/dL | The outcome kefir moves most reliably |
| Fasting insulin | 2–5 µIU/mL | Detects insulin resistance before glucose rises |
| HOMA-IR | Below 1.0 | Single index combining glucose and insulin |
| HbA1c | 4.8–5.2% | Confirms whether fasting gains persist across three months |
| hs-CRP | Below 0.5 mg/L | Tracks the inflammation signal that only appears after eight weeks |
| Apolipoprotein B | Below 80 mg/dL | Particle count is a better lipid readout than LDL cholesterol alone |
| Home blood pressure | Below 120/80 mmHg | Kefir's blood-pressure effect is small and disputed |
| 25-hydroxyvitamin D | 40–60 ng/mL | Determines whether kefir's calcium can be used for bone |
| Bone mineral density T-score | Above −1.0 | The only bone endpoint kefir has been tested against |
| Waist circumference | Below half of standing height | Catches the calorie load of sweetened kefir |
Cadence: Symptom tracking daily through the titration weeks; fasting glucose, insulin, lipids and inflammation repeated at 12 weeks, then every 6–12 months once intake is stable; bone density repeated no sooner than 24 months.