Propionate is a small fatty acid the body makes when gut bacteria ferment fiber, and that industry adds to food as a preservative. Colon-delivered propionate may curb appetite, steady blood sugar, and calm inflammation, while the swallowed additive form may work against insulin. Evidence is modest and mixed; eating more fermentable fiber is the safest way to raise it. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Fasting glucose | 70–85 mg/dL | Detects the proposed glucose-lowering benefit or any additive-related rise |
| Fasting insulin | 2–6 µIU/mL | Tracks insulin sensitivity, the key metabolic outcome studied |
| HbA1c | < 5.4% | Reflects 3-month average glucose, capturing sustained metabolic effect |
| hs-CRP | < 1.0 mg/L | Gauges the proposed anti-inflammatory effect |
| Lipid panel (total, LDL, HDL, triglycerides) | TG < 80 mg/dL; HDL > 50 mg/dL | Captures the modest lipid-modifying signal |
| Body weight / waist circumference | Stable or decreasing waist | Tracks the weight-maintenance outcome of the original trials |
| Vitamin B12 | > 500 pg/mL | Supports the B12-dependent propionate clearance pathway |
Cadence: Baseline before starting, at roughly 3 months after initiation, then every 6–12 months; more frequent glucose checks for anyone also using glucose-lowering medication