Limited evidenceLongevity & antioxidants

Watercress Extract

A crucifer rich in phenethyl isothiocyanate, sold for detoxification pathways. Two small human trials show changes in DNA damage and lipid markers; nothing establishes a clinical benefit.

Evidence last reviewed: August 2026

What the science says

DNA damage markers Limited evidence
A randomized crossover trial in 60 healthy adults found that eating 85 g of raw watercress daily for eight weeks reduced DNA damage in lymphocytes and altered blood antioxidant status. This used whole watercress as food, not a concentrated extract, and DNA damage in blood cells is a surrogate marker.
Lipids and oxidative stress Limited evidence
A randomized double-blind placebo-controlled trial of watercress extract in overweight people with physical disability reported changes in lipid profile and oxidative stress markers. The trial was small and in a narrow population, and the results have not been replicated.

Dosage & safety

Studied doseThe DNA damage trial used 85 g/day of fresh watercress. Extract capsules typically supply 250–500 mg/day standardized to a glucosinolate or PEITC content, a label dose without trial support.

SafetyWatercress as food is safe for most people. Concentrated extracts can irritate the stomach and, like other cruciferous vegetables, contain goitrogens that matter at high intake in iodine deficiency. Watercress inhibits CYP2E1 and may affect drug metabolism, and its high vitamin K content interacts with warfarin. Raw watercress from wild sources can carry liver fluke; use cultivated produce.

Scientific references

Watercress supplementation in diet reduces lymphocyte DNA damage and alters blood antioxidant status in healthy adults
Gill CI, Haldar S, Boyd LA — Am J Clin Nutr, 2007
Effect of watercress extract supplementation on lipid profile and oxidative stress markers in overweight people with physical disability: A randomized, double-blind, and placebo-controlled trial
Clemente M, Miguel MD, Felipe KB — Phytother Res, 2021

Where to buy

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