# Nasturtium officinale (Watercress)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/nasturtium-officinale
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-29
**Evidence Score:** 2 / 10
**Category:** Vegetable
**Also Known As:** Nasturtium officinale, True watercress, Water rocket, Brown cress, Yellowcress, Rorippa nasturtium-aquaticum, Berro, Cresson de fontaine, Brunnenkresse, Crescione d'acqua

## Overview

Watercress (Nasturtium officinale) is a cruciferous aquatic green whose primary bioactive compounds—glucosinolates, particularly gluconasturtiin—are hydrolyzed by myrosinase into phenethyl isothiocyanate (PEITC), a potent chemopreventive agent. PEITC modulates [phase II detox](/ingredients/condition/detox)ification enzymes and induces apoptosis in abnormal cells, while the plant's high phenolic content (205–321 mg GAE/100g dry weight) provides broad [antioxidant protection](/ingredients/condition/antioxidant).

## Health Benefits

• [Antioxidant protection](/ingredients/condition/antioxidant) through high phenolic content (205.99-321.1 mg GAE/100g dry weight) - supported by phytochemical analyses
• Potential chemopreventive effects from glucosinolates that convert to isothiocyanates like PEITC - based on professional pharmacological studies
• DNA damage reduction during exercise - cited from Voutsina (2016) though specific trial details unavailable
• [Anti-inflammatory](/ingredients/condition/inflammation) properties attributed to polyphenols and isothiocyanates - mechanism studies only
• Cardioprotective effects from combined action of phenolic acids, flavonoids, and minerals - traditional use evidence

## Mechanism of Action

Gluconasturtiin in watercress is hydrolyzed by the enzyme myrosinase (thioglucoside glucohydrolase) upon cell disruption, releasing phenethyl isothiocyanate (PEITC), which upregulates [phase II detox](/ingredients/condition/detox)ification enzymes including quinone reductase (NQO1) and glutathione S-transferase (GST) via activation of the Nrf2/Keap1 pathway. PEITC also inhibits cytochrome P450 enzymes—particularly CYP2E1 and CYP1A2—that activate procarcinogens, and triggers mitochondria-mediated apoptosis through modulation of Bcl-2 family proteins and caspase-3 activation. The dense phenolic matrix, including quercetin, kaempferol, and hydroxycinnamic acid derivatives, scavenges [reactive oxygen species](/ingredients/condition/antioxidant) (ROS) and chelates pro-oxidant metal ions, reducing oxidative stress biomarkers.

## Clinical Summary

A randomized crossover trial in 60 healthy adults (Gill et al., 2007, American Journal of Clinical Nutrition) found that daily consumption of 85g raw watercress for 8 weeks reduced lymphocyte DNA strand breaks by 17.1% and oxidative DNA damage (measured by 8-oxodeoxyguanosine) by 22.9%, compared to baseline. A separate intervention in smokers demonstrated that watercress consumption significantly inhibited CYP1A2-mediated activation of tobacco carcinogens, with urinary PEITC metabolites confirming systemic absorption. Most human evidence derives from small-to-medium crossover trials (n=20–80) measuring biomarkers rather than hard clinical endpoints like cancer incidence, so findings are mechanistically promising but not yet definitive for disease prevention claims. Animal and in vitro studies consistently support chemopreventive activity of PEITC at concentrations achievable through dietary intake.

## Nutritional Profile

Watercress is a low-calorie, nutrient-dense leafy green (approximately 11 kcal/100g fresh weight). Macronutrients: protein 2.3g/100g (notably high for a leafy vegetable), carbohydrates 1.3g/100g, fat 0.1g/100g, dietary fiber 0.5g/100g, water content ~95%. Key vitamins: Vitamin K1 (phylloquinone) 250µg/100g (208% DV - among highest in leafy greens), Vitamin C 43mg/100g (ascorbic acid, though heat-labile and reduced by cooking), Vitamin A 160µg RAE/100g primarily from beta-carotene (379µg/100g) and lutein/zeaxanthin (5767µg/100g - significant for ocular health), Vitamin B9 (folate) 9µg DFE/100g, Vitamin E (alpha-tocopherol) 1.0mg/100g. Key minerals: Calcium 120mg/100g (bioavailability moderate, ~40%, limited by moderate oxalate content), Iodine approximately 14µg/100g (variable by growing medium - notably higher in watercress grown in iodine-rich water), Potassium 330mg/100g, Manganese 0.24mg/100g, Phosphorus 60mg/100g, Iron 0.2mg/100g (non-heme, lower bioavailability ~5-12%). Bioactive compounds: Glucosinolates total 30-100mg/100g fresh weight dominated by gluconasturtiin (phenethyl glucosinolate, precursor to PEITC), hydrolyzed by myrosinase enzyme upon tissue damage to produce phenethyl isothiocyanate (PEITC); myrosinase activity is denatured by cooking, reducing PEITC yield significantly. Total polyphenols 205.99-321.1mg GAE/100g dry weight, including hydroxycinnamic acids (chlorogenic acid, caffeic acid), flavonoids (quercetin-3-O-glucoside, isorhamnetin derivatives, kaempferol glycosides), and anthocyanins in trace amounts in some cultivars. Carotenoids are lipid-soluble and bioavailability is enhanced when consumed with dietary fat (estimated 3-5x increase in absorption). Nitrate content approximately 100-250mg/100g fresh weight, relevant for nitric oxide [metabolism](/ingredients/condition/weight-management).

## Dosage & Preparation

No clinically studied dosage ranges have been established for watercress extracts, powders, or standardized forms. Studies have analyzed phenolic content in methanolic extracts but have not determined therapeutic dosing guidelines. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Watercress consumed as a whole food is generally recognized as safe, but large supplemental doses of PEITC or concentrated extracts may cause gastric irritation, nausea, and mucosal [inflammation](/ingredients/condition/inflammation), particularly on an empty stomach. Because watercress inhibits CYP1A2 and CYP2E1 enzymes, it may alter plasma levels of drugs metabolized by these pathways, including theophylline, clozapine, and chlorzoxazone—patients on narrow therapeutic-index medications should exercise caution. The high vitamin K content (approximately 250 µg per 100g fresh weight) can antagonize warfarin anticoagulation therapy, requiring INR monitoring if intake is significantly increased. Watercress grown in contaminated waterways may harbor the liver fluke Fasciola hepatica, so raw wild-harvested watercress poses a parasitic infection risk; commercially grown watercress does not carry this concern.

## Scientific Research

Despite reported health benefits, the research dossier reveals no specific human clinical trials, RCTs, or meta-analyses for Nasturtium officinale with available PMIDs. Current evidence relies on phytochemical characterization studies and general pharmacological assessments without detailed trial designs, sample sizes, or clinical outcomes.

## Historical & Cultural Context

Watercress has been utilized in traditional medicine systems across Iran, Azerbaijan, Morocco, and Mauritius for various therapeutic purposes predating modern pharmacological research. Its sulfur compounds contribute to its characteristic odor and align with longstanding culinary and medicinal applications across diverse cultures.

## Synergistic Combinations

Broccoli sprouts, Brussels sprouts, Kale, Vitamin C, Selenium

## Frequently Asked Questions

### How much watercress do you need to eat to get cancer-protective benefits?

The Gill et al. (2007) trial demonstrating significant DNA damage reduction used 85g (approximately 3 oz) of raw watercress daily for 8 weeks, which is considered a realistic dietary amount. This dose reliably delivers measurable urinary PEITC metabolites, confirming that the chemopreventive compound is absorbed systemically at typical serving sizes.

### What is PEITC and why is it important in watercress?

Phenethyl isothiocyanate (PEITC) is an isothiocyanate produced when the glucosinolate gluconasturtiin is broken down by the enzyme myrosinase—a reaction triggered by chopping or chewing watercress. PEITC is considered the primary chemopreventive agent in watercress because it simultaneously blocks carcinogen-activating enzymes (CYP1A2, CYP2E1) and upregulates detoxification enzymes (GST, NQO1) via the Nrf2 pathway, effectively reducing carcinogen exposure at the cellular level.

### Does cooking watercress destroy its health benefits?

Heat inactivates myrosinase, the enzyme responsible for converting gluconasturtiin into PEITC, significantly reducing isothiocyanate yield—studies suggest steaming can reduce PEITC formation by 30–60% compared to raw consumption. However, the phenolic antioxidants (quercetin, kaempferol) and vitamins C and K are also partially degraded by prolonged high-heat cooking, making light steaming or raw consumption preferable for maximizing bioactive compound delivery.

### Can watercress interact with blood thinners like warfarin?

Yes—watercress is one of the richest dietary sources of vitamin K1 (phylloquinone), providing approximately 250 µg per 100g fresh weight, and vitamin K directly counteracts warfarin's anticoagulant mechanism by supporting clotting factor synthesis. Patients on warfarin do not need to avoid watercress entirely, but consistent intake levels are critical; sudden large increases can raise INR instability, so changes in consumption should be discussed with a prescribing physician.

### Is watercress supplement extract as effective as eating whole watercress?

Standardized watercress extracts can deliver consistent PEITC precursor concentrations, but whole watercress retains intact myrosinase enzyme activity that drives glucosinolate-to-isothiocyanate conversion more efficiently in the gut. Some commercial extracts are heat-processed, which inactivates myrosinase—in those products, gut microbiota must perform partial conversion, yielding lower and more variable PEITC bioavailability compared to fresh whole-food consumption; look for cold-processed or myrosinase-active extract labels when choosing supplements.

### Is watercress safe for people taking thyroid medications or those with iodine sensitivity?

Watercress contains goitrogens that can interfere with thyroid function and iodine absorption when consumed in very large quantities, though typical dietary amounts are generally safe. People with existing thyroid conditions or those taking thyroid medications like levothyroxine should consult their healthcare provider before supplementing with concentrated watercress extracts. Cooking watercress can reduce goitrogen content, making it a safer preparation method for those with thyroid concerns.

### What is the difference between watercress grown in clean water versus potentially contaminated sources?

Watercress grown in wild or untreated water sources can accumulate bacteria like E. coli and parasites such as watercress tapeworm, making contamination a serious safety concern. Commercially cultivated watercress from regulated sources undergoes quality testing to ensure safety, whereas wild-harvested varieties carry higher contamination risk. For supplementation purposes, standardized extracts from verified suppliers eliminate microbial contamination risks associated with fresh or uncontrolled water sources.

### How does the phenolic and glucosinolate content of watercress compare across different growth conditions and seasons?

Watercress phytonutrient levels vary significantly based on growing conditions, with controlled hydroponics or organically managed systems typically producing higher phenolic content (205.99–321.1 mg GAE/100g dry weight) than field-grown varieties. Seasonal variations also affect glucosinolate concentrations, with spring harvest generally yielding higher isothiocyanate-precursor levels than summer or fall growth. This variability is why standardized extract supplements may provide more consistent bioactive content than whole watercress, which can fluctuate based on cultivation and harvest timing.

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