A compound the body makes, sold in Europe as a nerve-damage medicine and elsewhere as a supplement. No controlled study has counted hairs; the only human hair data come from cancer patients using a scalp lotion. Safety is better characterised than benefit — stomach upset is common, scalp application irritates. Against agents with hair-count evidence, that gap is decisive. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Ferritin | 70–100 ng/mL | Iron stores gate hair shedding |
| Fasting glucose | 75–90 mg/dL | Detects additive glucose lowering |
| Fasting insulin | 2–5 µIU/mL | Insulin resistance drives androgen-pattern loss in women |
| HbA1c | 4.8–5.4% | Confirms glycaemic direction over months |
| TSH | 0.5–2.0 mIU/L | Thyroid disease causes diffuse shedding and may be affected by absorption interference |
| 25-hydroxyvitamin D | 40–60 ng/mL | Low status is an independent driver of shedding |
| Serum zinc | 90–120 µg/dL | Chelation may reduce absorption of a mineral hair depends on |
| Urine albumin-to-creatinine ratio | Below 10 mg/g | Detects the protein leak of supplement-associated membranous nephropathy |
| Insulin autoantibodies | Negative | Confirms or excludes the one serious documented harm |
| Hair density by phototrichogram | No established target; track change from the individual's own baseline in hairs per cm² | The only direct measure of the intended outcome |
Cadence: Fasting glucose at 1 and 2 weeks; full metabolic and iron panel plus thyroid function at 3 months; urine protein check at 3 and 12 months; repeat photography at 3, 6 and 12 months, then every 6–12 months thereafter if use continues.