An essential nutrient with a clean safety record. Replacing a genuine shortfall — from heavy alcohol intake, weight-loss surgery, long-term fluid tablets, poor absorption, or a restricted diet — reverses serious nerve, brain, and heart problems. Much larger amounts in well-supplied people have left blood sugar, heart function, and nerve damage untouched. Two large trials are pending. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Whole-blood thiamine diphosphate | 90–180 nmol/L | The direct measure of the active coenzyme and body status |
| Erythrocyte transketolase activation coefficient | Below 1.15 | Functional test of whether the enzyme is short of its coenzyme |
| Serum or red-cell magnesium | Red-cell magnesium 5.0–6.5 mg/dL | Required cofactor for converting thiamine to its active form |
| Alanine aminotransferase | 10–26 U/L | Detects the liver-enzyme rise reported on high-dose benfotiamine |
| Fasting glucose and glycated haemoglobin | Fasting glucose 75–90 mg/dL; glycated haemoglobin 4.8–5.4% | Tracks the metabolic endpoint that supplementation trials targeted |
| Serum lactate | Below 1.5 mmol/L at rest | Rises when the thiamine-dependent step in energy metabolism is limited |
| Urinary albumin-to-creatinine ratio | Below 10 mg/g | The endpoint that improved in the diabetic kidney pilot trial |
Cadence: Baseline before the first dose; whole-blood thiamine diphosphate at 4–8 weeks to confirm correction of a documented deficit; liver enzymes and magnesium at 8–12 weeks, then every 6–12 months on open-ended high-dose use.