Phenethyl isothiocyanate, a plant compound in watercress, draws interest for cancer prevention and longevity. Small human studies show it changes how the body handles certain toxins; whether this lowers cancer rates or extends healthy life has never been tested. Side effects are mostly mild stomach and mouth irritation; it can alter how some medications are handled. Evidence supports it as a plausible, low-cost add-on through food, of uncertain long-term value. (Full Review)
| Marker | Target | Why |
|---|---|---|
| ALT and AST | ALT 7–55 U/L; AST 8–48 U/L | Liver safety check |
| Urinalysis for blood | Negative for blood | Bladder safety check |
| INR (warfarin users only) | No established target for PEITC; track change from the individual's stable baseline | Safety check for warfarin dosing |
| Urinary PEITC-NAC | No established target; track change from the individual's own baseline | Confirms intake and absorption |
Cadence: Baseline before purified PEITC; liver enzymes at 4–8 weeks, then every 6–12 months during continued purified use; urinalysis every 6–12 months; INR within 1–2 weeks of starting or changing dose for warfarin users. Watercress eaten as food in normal amounts needs no special testing.