Neem is a tree whose leaf, bark and seed oil are sold as supplements, oral care and skin products. Human evidence is strongest in the mouth, where rinses, pastes and chewing sticks match standard products on plaque and gum inflammation. Beyond the mouth, the findings come from single studies only. Ingested seed oil causes severe brain and liver illness in infants; seed preparations block fertility in animals. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Alanine aminotransferase | 10–26 U/L (men), 8–22 U/L (women) | Earliest signal of the liver injury seen in animal toxicity studies |
| Aspartate aminotransferase | 10–26 U/L | Confirms and contextualises any alanine aminotransferase rise |
| Fasting glucose | 75–86 mg/dL | Tracks the intended metabolic effect and flags additive hypoglycaemia |
| Glycated haemoglobin | 4.8–5.2% | Confirms whether the glucose effect is real over months, not day to day |
| Estimated glomerular filtration rate | >90 mL/min/1.73 m² | Kidney function is the second organ affected in animal high-dose studies |
| Complete blood count | Within reference, stable against own baseline | Detects the marrow and red cell changes reported in animal chronic dosing |
| Semen concentration and motility | >40 million/mL, >45% progressive motility | The only direct measure of the documented animal antifertility signal |
| International normalised ratio | 2.0–3.0 if on warfarin; otherwise 0.9–1.1 | Captures the CYP2C9 interaction risk directly |
Cadence: Liver and kidney markers at 6–8 weeks, then every 3–6 months while use continues; glucose markers at 12 weeks, then every 6 months. Neem seed oil products, or doses above those tested in trials, fall into the shorter interval.