A fat-soluble form of vitamin B1 built to reach the brain more easily, used for energy, motivation, mood, and mental clarity. The most credible evidence points to modest, short-term relief of low-grade fatigue, though the best-controlled trial found no lasting effect. A plausible but under-proven short-term, intermittent option with a clear potential for habit-forming use. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Thiamine status (whole-blood thiamine or erythrocyte transketolase activity) | Mid-to-upper normal | Confirms whether low B1 might explain fatigue and predict response |
| Thyroid panel (TSH, free T4) | TSH ~0.5–2.5 mIU/L (functional) | Excludes hypothyroidism as a cause of fatigue before attributing benefit to sulbutiamine |
| Complete blood count (focus on hemoglobin) | Hemoglobin mid-normal for sex | Excludes anemia as a fatigue cause |
| Ferritin | ~50–150 ng/mL (functional) | Low iron stores are a common, treatable fatigue driver |
| Fasting glucose / HbA1c | Glucose ~70–90 mg/dL; HbA1c <5.4% (functional) | Screens for dysglycemia contributing to fatigue, relevant given animal data in diabetes |
Cadence: Reassess subjective response, sleep, and mood at roughly 1 week and 4 weeks, then periodically (every few months) if continued, with prompt reassessment if mood, sleep, or craving worsens.