Sulbutiamine, a laboratory-made form of vitamin B1 that enters the brain easily, is sold online for focus and energy. Modest human signals, each from one small trial: better memory alongside Alzheimer's treatment, better nerve signaling in diabetic nerve damage, faster recovery of drive during depression treatment. Fatigue relief is disputed. Short courses appear well tolerated; concerns include mood swings in bipolar disorder and sports drug-test confusion. Long-term value remains uncertain. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Whole-blood thiamine diphosphate | 120–180 nmol/L | Thiamine status |
| Erythrocyte transketolase activity coefficient (ETKAC) | Below 1.15 | Functional thiamine sufficiency |
| Red blood cell magnesium | 5.0–6.5 mg/dL | Magnesium is needed to activate thiamine |
| eGFR and creatinine | eGFR above 90 mL/min/1.73 m² | Kidneys clear thiamine metabolites |
| ALT | Below 25 U/L | Liver safety check |
| Fasting glucose and HbA1c | Glucose 75–90 mg/dL; HbA1c below 5.4% | Diabetes drives thiamine loss and neuropathy |
| Nerve conduction study (if neuropathy) | No established target; track change from own baseline | Objective nerve function |
Cadence: Baseline before a first course; symptom and sleep check at 1 week; repeat fatigue questionnaire at 4 weeks; repeat thiamine and kidney labs at the end of each course or every 6–12 months for repeated courses