NutriDex

The Supplement Research Compendium

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watercress

A peppery, near-zero-calorie cruciferous green that delivers an outsized hit of vitamin K, vitamin C and the carcinogen-detoxifying isothiocyanate PEITC.

Moderate evidence 🥦Vegetables
Evidence tier
Moderate
Research weight
Citations
10 verified / 10
Classification
Vegetables
What the evidence says. Several controlled trials; effects real but modest or context-dependent.

Nutrition per serving 1 cup chopped, raw (34 g)

34gSERVING
  • Sugars 0.1 g0%
  • Fibre 0.2 g1%
  • Other carbs 0.1 g0%
  • Protein 0.8 g2%
  • Other 32.8 g96%
What's in one serving, by weight — average composition (USDA).
Vitamin C16%Fiber1%Potassium2%Folate1%Vitamin A6%Vitamin K71%Vitamin B63%Manganese4%
One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
3.7 kcal0.8 g protein0.2 g fiber0.07 g sugar
NutrientPer serving% daily value
Vitamin C15 mg16%
Fiber0.2 g1%
Potassium112 mg2%
Folate3 µg1%
Vitamin A54 µg6%
Vitamin K85 µg71%
Vitamin B60.04 mg3%
Manganese0.08 mg4%
Copper0.03 mg3%
Vitamin E0.34 mg2%
Magnesium7 mg2%
Calcium41 mg3%

Composition data: USDA FoodData Central ↗

What is watercress?

watercress is a vegetable used for enhances detoxification of environmental and tobacco carcinogens (peitc). NutriDex grades the human evidence as Moderate. Watercress is a nutrient-dense cruciferous leaf whose signature bioactive, phenethyl isothiocyanate (PEITC, from gluconasturtiin), has been tested in human trials. A randomized crossover study showed 85 g/day of raw watercress for 8 weeks cut lymphocyte DNA damage and roughly doubled plasma lutein, and randomized phase-2 trials of PEITC or a freeze-dried watercress beverage significantly boosted urinary detoxification of tobacco-related and environmental carcinogens (acrolein, benzene, crotonaldehyde) and modestly inhibited activation of the lung carcinogen NNK in smokers. Large prospective cohorts and meta-analyses of cruciferous vegetables as a class link higher intake to lower cardiovascular and colorectal-cancer risk, though watercress-specific hard-outcome data remain limited.

Purported Benefits

Enhances detoxification of environmental and tobacco carcinogens (PEITC)
Reduces lymphocyte DNA damage and oxidative stress
Raises plasma carotenoids (lutein, beta-carotene)
Cruciferous intake linked to lower CVD and colorectal-cancer risk
Exceptional vitamin K and vitamin C density at near-zero calories

Dosing & Compounds

Typical Dose
Standard serving: 1 cup chopped, raw (34 g). Eat whole (with skin where edible); favour whole fruit over juice.
Active Compounds
phenethyl isothiocyanate (PEITC)gluconasturtiinluteinbeta-carotenevitamin K1 (phylloquinone)quercetin

Safety & Cautions

Very high in vitamin K1 (~85 ug per cup) — people on warfarin should keep intake consistent to avoid destabilizing INR. As a raw cruciferous green it contains goitrogenic glucosinolates, of possible concern only at very high intakes with iodine deficiency. Generally well tolerated; wild-harvested watercress can carry liver-fluke (Fasciola) or waterborne-pathogen risk, so use cultivated/washed produce. Educational only — always check with your doctor or pharmacist before combining watercress with any medicine.

Key Studies ★ 10 studies

Systematic review Wen 2025 (Food Sci Nutr) ✓ Full text
Systematic review of RCTs found watercress supplementation improved antioxidant and anti-inflammatory markers at short-term follow-up, though effects were modest and evidence limited by small trial sizes.
Meta-analysis Pollock 2016 (meta-analysis) ✓ Full text
Meta-analysis reported green-leafy and cruciferous vegetable intake associated with ~15.8% lower cardiovascular-disease incidence (RR 0.842, 95% CI 0.753-0.941, P=0.002).
Meta-analysis Wu 2013 (meta-analysis) ✓ PubMed
Meta-analysis of observational studies found higher cruciferous-vegetable intake associated with a significantly lower colorectal-cancer risk (RR 0.82, 95% CI 0.75-0.90).
RCT (randomized crossover) Hecht / watercress-beverage trial 2026 (RCT) ✓ Source
Two-site randomized crossover (188 completers) of a freeze-dried watercress beverage (2 wk) significantly increased urinary mercapturic-acid detoxification of acrolein (+65.6%) and benzene (+37.3%) plus other toxicants versus placebo.
RCT (phase 2 crossover) Hecht 2016 (RCT) ✓ Full text
Randomized phase-2 crossover in 82 smokers: PEITC (the watercress isothiocyanate) produced a modest but significant 7.7% inhibition of metabolic activation of the lung carcinogen NNK versus placebo.
RCT (randomized crossover) Fogarty 2013 (RCT) ✓ Source
Acute and 8-wk chronic watercress supplementation in trained men (n=10) attenuated exercise-induced peripheral mononuclear-cell DNA damage and lipid peroxidation versus control.
RCT (randomized crossover) Gill 2007 (RCT) ✓ PubMed
85 g/day raw watercress for 8 wk in 60 adults reduced basal lymphocyte DNA damage by 17% (P=0.03) and oxidative purine DNA damage by 23.9% (P=0.002), with plasma lutein +100% and beta-carotene +33% (P<0.001).
Review Watercress functional food review 2025 (Life/MDPI) ✓ Full text
Narrative review of 88 sources (2019-2025) summarizing watercress glucosinolate/PEITC effects on non-communicable diseases, noting antioxidant, anti-inflammatory, and metabolic effects while emphasizing scarcity of robust human trials.
Observational Charron 2022 (Cancer Prev Res) ✓ PubMed
Methods paper describing preparation of a standardized freeze-dried watercress beverage delivering reproducible PEITC for the NCT03978117 carcinogen-detoxification clinical trial.
Prospective cohort Zhang 2011 (cohort) ✓ Full text
In 134,796 Chinese adults, highest vs lowest cruciferous-vegetable intake was associated with lower total mortality (HR 0.78, 95% CI 0.71-0.85) and cardiovascular mortality (HR 0.69, 95% CI 0.56-0.85).

Common questions about watercress

What is watercress used for?

watercress is most often taken for Enhances detoxification of environmental and tobacco carcinogens (PEITC), Reduces lymphocyte DNA damage and oxidative stress, Raises plasma carotenoids (lutein, beta-carotene), Cruciferous intake linked to lower CVD and colorectal-cancer risk. A peppery, near-zero-calorie cruciferous green that delivers an outsized hit of vitamin K, vitamin C and the carcinogen-detoxifying isothiocyanate PEITC.

Does watercress work — what does the evidence say?

Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Watercress is a nutrient-dense cruciferous leaf whose signature bioactive, phenethyl isothiocyanate (PEITC, from gluconasturtiin), has been tested in human trials. A randomized crossover study showed 85 g/day of raw watercress for 8 weeks cut lymphocyte DNA damage and roughly doubled plasma lutein, and randomized phase-2 trials of PEITC or a freeze-dried watercress beverage significantly boosted urinary detoxification of tobacco-related and environmental carcinogens (acrolein, benzene, crotonaldehyde) and modestly inhibited activation of the lung carcinogen NNK in smokers. Large prospective cohorts and meta-analyses of cruciferous vegetables as a class link higher intake to lower cardiovascular and colorectal-cancer risk, though watercress-specific hard-outcome data remain limited.

What is the typical dose of watercress?

Standard serving: 1 cup chopped, raw (34 g). Eat whole (with skin where edible); favour whole fruit over juice.

Is watercress safe? Any cautions or side effects?

Very high in vitamin K1 (~85 ug per cup) — people on warfarin should keep intake consistent to avoid destabilizing INR. As a raw cruciferous green it contains goitrogenic glucosinolates, of possible concern only at very high intakes with iodine deficiency. Generally well tolerated; wild-harvested watercress can carry liver-fluke (Fasciola) or waterborne-pathogen risk, so use cultivated/washed produce.

How many studies support watercress?

NutriDex cites 10 sources for watercress, graded "Moderate".

Cite this page
APA

Peh, D. (2026). watercress: Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/watercress

BibTeX
@misc{nutridex_watercress,
  author       = {Peh, Daryl},
  title        = {watercress: Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/watercress},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

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