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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.

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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.

How to take it

TimingTiming does not matter.
With food?With food; concentrated extracts irritate an empty stomach.
Worth knowingThe trial used 85 g of fresh watercress a day, so a daily bag of salad is closer to the evidence than a capsule — and use cultivated, not wild, watercress.

Interactions

With medications

  • warfarin

    Watercress is high in vitamin K, which opposes warfarin. keep intake steady day to day rather than starting and stopping, and tell your anticoagulation clinic

  • drugs cleared by CYP2E1 (including paracetamol/acetaminophen and chlorzoxazone)

    Watercress inhibits CYP2E1 and can slow their metabolism. avoid concentrated extracts alongside these without medical advice

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does watercress reduce DNA damage?

A randomized crossover trial in 60 healthy adults found 85 g of raw watercress daily for eight weeks reduced DNA damage in blood cells. That is a surrogate marker, it used whole watercress rather than an extract, and the evidence is limited.

Is watercress extract as good as eating watercress?

Not shown: the stronger watercress trial used 85 g/day of the fresh vegetable, and extract capsules supplying 250–500 mg/day have no trial support for that dose. A daily bag of cultivated watercress is closer to the evidence.

Can I take watercress with warfarin?

Watercress is high in vitamin K, which opposes warfarin, so keep your intake steady rather than starting and stopping, and tell your anticoagulation clinic. Watercress also inhibits CYP2E1, which can slow the metabolism of drugs such as paracetamol.

Is watercress extract safe?

Watercress as food is safe for most people, but concentrated extracts can irritate the stomach and contain goitrogens that matter at high intake in iodine deficiency. Avoid wild watercress, which can carry liver fluke.

Scientific references

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