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Watercress powder

Also known as: Watercress, Nasturtium officinale

Overview

Watercress (*Nasturtium officinale*) is an aquatic leafy green vegetable widely consumed as food and as a dietary supplement in powdered or extract form. It is rich in beneficial phytochemicals, notably phenethyl isothiocyanate (PEITC), along with various vitamins and antioxidants. Research indicates its primary applications are linked to its potent antioxidant and anti-inflammatory properties, as well as its promising chemopreventive potential. While several randomized controlled trials and systematic reviews support its biological effects, large-scale clinical trials are still limited. Watercress is generally recognized for its ability to combat oxidative stress and modulate detoxification pathways within the body.

Benefits

Watercress offers several evidence-based benefits, primarily due to its rich phytochemical content. Systematic reviews of randomized controlled trials (RCTs) consistently show that watercress supplementation significantly enhances antioxidant status and reduces inflammatory markers in humans, providing protection against oxidative stress-related damage. Its chemopreventive potential is notable, as its active compound, PEITC, has been shown to inhibit the metabolism of carcinogens like NNK (a lung carcinogen) and reduce DNA damage, suggesting a role in cancer prevention, particularly lung cancer in smokers. Clinical evidence also points to hepatoprotective effects, with watercress intake potentially reducing liver toxicity by decreasing oxidative metabolites of drugs such as acetaminophen. While human data are limited, animal studies suggest that low doses of watercress juice may help prevent renal stone formation. Preclinical studies also indicate potential glucose-lowering effects at high extract doses, though this requires further human validation.

How it works

The beneficial effects of watercress are primarily mediated by its bioactive compounds, particularly phenethyl isothiocyanate (PEITC). PEITC acts as a potent antioxidant by directly scavenging free radicals and enhancing the activity of endogenous antioxidant enzymes within the body. Furthermore, PEITC plays a crucial role in modulating phase I and phase II detoxification enzymes, which helps to inhibit the activation of procarcinogens and promote their efficient excretion from the body. Its anti-inflammatory effects are achieved through the downregulation of pro-inflammatory cytokines and a reduction in oxidative stress markers. The phytochemicals in watercress are absorbed in the gastrointestinal tract, with their bioavailability influenced by the form of consumption (fresh, powder, or extract).

Side effects

Watercress is generally considered safe for consumption, both as a food and as a supplement, when taken within recommended dietary or studied supplemental amounts. Documented common side effects are minimal and not well-reported. While no significant adverse drug interactions have been widely reported in controlled studies, caution is advised for individuals taking anticoagulant medications due to watercress's vitamin K content, which can affect blood clotting. Specific contraindications are not well-established; however, individuals with pre-existing thyroid disorders should exercise caution due to the potential goitrogenic properties inherent in cruciferous vegetables, which could interfere with thyroid function. Overall, its safety profile is favorable in short-term studies, but long-term safety data are still limited.

Dosage

Clinical trials investigating watercress have utilized a range of dosages. For fresh watercress, an effective dose for antioxidant and chemopreventive effects has been observed at 50 grams daily for two weeks in human studies, which typically provides approximately 13 mg of PEITC. Animal studies have explored various extract doses, such as 100 mg/kg. The timing of intake is generally flexible, often consumed with meals. While these dosages have shown efficacy in short-term studies, the optimal dosing for long-term use and specific health conditions remains undetermined. More randomized controlled trials are needed to establish standardized dosing guidelines, upper limits, and safety thresholds for different forms and purposes of watercress supplementation.

FAQs

Is watercress powder effective?

Yes, powdered forms of watercress retain bioactive compounds, but their bioavailability might vary compared to fresh leaves. Research supports its antioxidant and anti-inflammatory benefits.

How quickly do benefits appear?

Antioxidant and anti-inflammatory effects have been observed within as little as two weeks of consistent watercress supplementation in human studies.

Is it safe long-term?

While short-term studies show a good safety profile, limited long-term human data exist. It is generally considered safe in dietary amounts.

Can it replace medications?

No, watercress is a complementary supplement and should not be used as a substitute for prescribed medical treatments or professional medical advice.

Research Sources

https://www.phcogrev.com/sites/default/files/PhcogRev_2019_13_25_10.pdf – This preclinical review from 2019 discusses various animal studies on watercress, highlighting its dose-dependent glucose-lowering effects, potential for renal stone prevention, and immune modulation. It provides mechanistic insights but notes the limited human translation of these findings, indicating lower clinical relevance for some aspects.
https://pmc.ncbi.nlm.nih.gov/articles/PMC12141087/ – This systematic review of randomized controlled trials (RCTs) confirms the antioxidant and anti-inflammatory effects of watercress supplementation in humans. It synthesizes findings from multiple studies, supporting watercress's role in improving antioxidant status and reducing inflammation markers, despite some limitations in the number and sample sizes of included RCTs.
https://www.arcjournals.org/pdfs/ijmpnp/v5-i3/2.pdf – This review of clinical trials from 2019, encompassing four studies on healthy volunteers and smokers, indicates that watercress reduces oxidative stress, DNA damage, and carcinogen metabolism. It supports the protective effects of watercress, particularly in relation to cancer prevention, though it acknowledges the small sample sizes and limited number of trials.
https://pubmed.ncbi.nlm.nih.gov/40488189/ – This source, likely a systematic review or meta-analysis, further corroborates the antioxidant and anti-inflammatory benefits of watercress supplementation. It contributes to the body of evidence supporting watercress's role in mitigating oxidative stress and inflammation, reinforcing findings from other high-quality reviews.