Watercress

Last Updated: November 18 2022

Watercress is a peppery vegetable in the family Brassicaceae, which includes broccoli. Eating watercress may help protect against carcinogens and chemotherapy drugs.

Watercress is most often used for.



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    1.

    Sources and Composition

    1.1

    Sources

    Watercress is the common name for the herb Nasturtium officinale (of the family Brassicaceae) which is a commonly consumed vegetable with a peppery taste. It is one of many herbs to be used against scurvy, due to its Vitamin C content.[1] Due to it belonging to the Brassicaceae family, it is known as a cruciferous vegetable (similar to broccoli and cauliflower).[2]

    Watercress should not be confused with 'Nasturtium seeds' which, despite bearing the name of the genus, refer to the plant Tropaeolum majus (commonly called Garden Nasturtium or Indian Cress).[3][4]

    A vegetable in the same family as broccoli, commonly used as a vegetable (usually in salads, due to its leafy composition) and carried many of the same properties as well as a peppery taste

    1.2

    Composition

    Watercress tends to contain:

    • Gluconasturtiin, a glucosinolate at 0.06–0.21µmol/g dry weight[5] which is the thioglucoside conjugate of β-phenylethyl isothiocyanate (PEITC) that is itself found at 23.7-29.7μmol/g dry weight[2]
    • Glucobrassicin (0.01-0.02µmol/g dry weight[5])
    • 4-methoxyglucobrassicin (0.06–0.18µmol/g dry weight[5])
    • 6-Methylsulfinylhexyl (0.2-0.3µmol/g dry weight), 7-methylsulfinylheptyl (3.9-7.5µmol/g dry weight), and 8-methylsulfinyloctyl (2.1-4.3µmol/g dry weight) isothiocyanates[2]
    • 7-Methylthioheptyl (1.2-2.5µmol/g) and 8-Methylthiooctyl (0.7-1.3µmol/g) isothiocyanates[2]
    • β-Carotene (5.919mg/100g wet weight) with no detectable α-Carotene[6][7]
    • Lutein (10.713mg/100g wet weight), no detectable Lycopene nor β-Cryptoxanthin[6][7]
    • Apigenin and glycosides[8]
    • Kaempferol (mostly glucosides, diglucosides, and some glycones with rhamnose)[9]
    • Quercetin (glucorhamnoside and diglucorhamnoside)[9]
    • Vitamin C at 104mg/100g fresh weight[9]

    While S-(N-β-Phenylethylthiocarbomyl)glutathione (PTCG) has been found to spontaneously and metabolically form from other glucosinates in watercress, without occurring naturally.[2] The concentration in this particular study merely being 12.5nM and less than 1% of total hydrolysed β-phenylethyl glucosinolate (a minor metabolite).[2] It may be formed from PEITC, as this study noted that PEITC was not found in tested extracts.[2]

    In general, watercress carries the same bioactives as other plants in the same family (Brassicaceae) although due to the gluconasturtiin content it contains a relatively high level of the isothiocyanate known as PEITC

    While the essential oil (volatile compounds) include:

    • Myristicin (57.6% of the leaves and not detected in stems or flowers[10])
    • α-terpinolene (8.9% of the leaves, 15.2% and 19.7% of the stems and flowers[10])
    • Limonene (6.7% of the leaves, but 11.8% and 43.6% of the stems and flowers[10])
    • β-Caryophyllene (13.1% stems, 6.6% of the flowers, and 4.3% leaves[10])
    • Caryophyllene oxide (37.2% of the stem, 6.7% of the flower, 4.2% of the leaves[10])
    • p-cymene-8-ol (17.6% of the stem, 7.6% of the flower, 3.1% of the leaves[10])
    • Neophytadienen (1.6% of the flowers, 1.5% of the leaves, and 0.8% of the stems[10])

    The essential oil is a surprisingly good source (percentage wise) of Myristicin, the hallucinogenic substance in nutmeg; this may not be high enough overall to induce a trip, however

    By weight, the essential oil is approximately 1.5% (stems), 1.2% (leaves) and 1.0% (flowers) and, when isolated, the essential oil does not contain polyphenolics nor flavonoids.[10]

    An extract (80:20 aqueous:ethanolic) of watercress has a polyphenolic content of 96.6+/-3.5mg/g as gallic acid equivalents (9.6%) and total flavonoid content of 62.3+/-2.4mg/g as catechin equivalents (6.2%; 64% of the phenolics).[11] Comparatively speaking, Watercress appears to be one of the highest common sources of Lutein (including parsley and spinach) although the most common dietary source are tomatoes; β-Carotene is also higher in watercress than most tested common vegetables excluding carrots.[6] This content of polyphenolics, relative to other Brassicaceae vegetables of leafy composure (mizuna and rocket) watercress has a higher phenolic content and a higher Vitamin C content.[9]

    Although watercress may bioaccumulate metals, it appears to have defenses against such[12] and is thought to play a role as a phytoremediator in moderately polluted aquatic ecosystems.[12]

    2.

    Pharmacology

    2.1

    Serum

    It has been estimated that, due to the gluconasturiin content, consumption of approximately an ounce of watercress results in exposure to approximately 2-6mg of PEITC in humans[13][14][15] and that consumption of 80g watercress has been noted to increase serum PEITC to 297nM on average (large range of 61-656nM) at a Tmax generally between 90-185 minutes,[16] while 100g watercress has been noted to increase serum PEITC to 928nM.[17]

    Watercress consumption is able to increase circulating levels of PEITC, although in an unreliable manner

    3.

    Cardiovascular Health

    3.1

    Cholesterol

    In hypercholesterolemic rats, 500mg/kg watercress daily for 30 days has been noted to reduce triglycerides (43%), LDL-C (49%), and total cholesterol (37%) while increasing HDL-C (16%); a beneficial influence on liver enzymes was noted as well, with reductions of ALT (39%), AST (42%), and ALP (40%).[18] These effects were thought to be secondary to its antioxidant properties,[18] and have been seen with a hydroalcoholic extract in rats fed a high fat diet, where oral ingestion of 500mg/kg of this watercress extract for 30 days normalized total cholesterol, LDL-C, and triglycerides with a small spike in HDL-C with a similar benefit to liver enzyme levels.[19]

    Both studies suggest that the beneficial effects of watercress on lipoproteins are secondary to hepatic interactions, which are disturbed in rats fed a high fat and high cholesterol diet.[18][19]

    Animal evidence to suggest (surprisingly potent) anti-cholesterol and anti-triglyceride effects in rats fed a high fat diet, which is thought to be secondary to antioxidant effects in liver tissue. Currently no human evidence

    4.

    Interactions with Oxidation

    4.1

    Mechanisms

    The antioxidant potential of watercress is shown in a concentration dependent manner against lipid peroxidation (EC50 273.5μg/mL, underperfoming relative to catechin at 10.1μg/mL[11]), iron chelation (538.6μg/mL, underperforming relative to EDTA at 5μg/mL[11]), DPPH free radical scavenging (114.7μg/mL, underperforming to Vitamin C at 3.5μg/mL[11]), ABTS+ inhibition (60.8μg/mL, underperforming to Trolox at 11.2μg/mL[11]), nitric oxide inhibition (395.2μg/mL, somewhat comparable to catechin at 332.1μg/mL[11]), and hydrogen peroxide scavenging activity (312.4μg/mL, somewhat comparable to Vitamin C at 106.2μg/mL[11]). Concentrating watercress for the ethanolic extract increases potency of the antioxidant parameters, but not enough to surpass reference compounds.[20]

    The essential oil components also possesses antioxidant properties,[10] with that of the leaves (IC50 87.0+/-0.9µg/mL) being more potent than the stem or flower in a DPPH assay (but less potent than the reference compound BHT at 18.0+/-0.3µg/mL).[10]

    Compounds in watercress appear to have direct anti-oxidant properties, although they are not remarkably potent in vitro relative to reference compounds

    4.2

    Genomic Damage

    15 days of supplementation of 0.5-1g/kg of watercress to rats was unable to induce genomic damage inherently but showed some protection against cyclophosphamide-induced genotoxicity as assessed by bladder histological changes; the protective effects were also replicated in vitro in a concentration-dependent manner.[21] This DNA protective effect has been noted in vitro elsewhere.[18]

    May protect DNA from oxidative damage

    4.3

    Interventions

    An increase in antioxidant capacity of the blood has been noted in rats with high cholesterol consuming 500mg/kg of watercress daily for 30 days, where the increase in hepatic lipid peroxidation and subsequent decrease in hepatic glutathione were not only normalized but the correction surpassed control (with the hypercholesterolemic rats given watercress having less lipid peroxidation and more glutathione than non-hypercholesterolemic control rats).[18] Similar trends were noted for Catalase, SOD, and glutahione reductase and peroxidase.[18]

    8 weeks of consumption of 85g watercress daily has been noted to influence anti-oxidant enzymes in humans, although the effect was only noted in red blood cells (not white blood cells) and the small increase in gluthione peroxidase and SOD were limited GSMT1*0 genotype (of which 44/60 persons had).[22] This genotype is associated with having a more profound anti-cancer association with cruciferous vegetables[23][24] which is thought to be due to a slower excretion rate of isothiocyanates and thus prolonged circulating levels;[22] This study noted that the other genotypes had a trend towards enhanced glutathione peroxidase and SOD, but that the increases were not statistically significant.

    These observations have been noted earlier in healthy adults consuming 85g watercress daily, and have been noted to be more significant in smokers relative to nonsmokers.[25]

    Two studies have confirmed some bioactivity of daily watercress consumption in regards to antioxidative parameters, with one noting a reduction in DNA damage in lymphocytes (white blood cells) while the other noted a genotype-dependent induction of anti-oxidant enzymes

    5.

    Interactions with Cancer Metabolism

    5.1

    Mechanisms

    Glucosinolates are thought to confer chemoprotective effects via modulating phase I and II enzymes (enzymes involved in drug bioactivation and excretion).[2]

    Induction of Quinone reductase is observed with S-(N-β-Phenylethylthiocarbomyl)glutathione (PTCG) although at concentrations 400-fold higher than found in the food product;[2] 7-Methylsulfinylheptyl and 8-methylsulfinyloctyl isothiocyanates were found to induce the enzyme 2-fold at 0.2µM and 0.5µM (similar potency to other sulfated isothiocyanates including 4-methylsulfinylbutyl isothiocyanate (sulforaphane)[26][27]).

    Appears to induce quinone reductase, with a few bioactives capable of doing so with similar potencies to sulforaphane

    PEITC has been shown previously to inhibit the protein known as 4E-BP1 which may mediate some anti-cancer activity (via suppressing activities of HIF),[28][29] and this has been shown to occur in vivo in women, where consumption of 80g watercress increased serum PEITC to 297nM and suppressed 4E-BP1 phosphorylation in lymphocytes of tested persons at 6-8 hours after ingestion although the degree of suppression was fairly unreliable.[16]

    Appears to inhibit 4E-BP1, which has been noted in a small sample of humans following oral ingestion of 80g watercress

    6.

    Nutrient-Nutrient Interactions

    6.1

    Nicotine

    Nicotine is a stimulatory alkaloid found most commonly in cigarettes and stop smoking aids.

    Watercress consumption has been found to increase the urinary metabolites 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNAL) and its glucuronide.[14][15] This was thought to be due to either an increase in glucuronidation or an inhibition of CYP1A2 (aromatase).[15]

    Three days of consumption of two ounces (56.8g) of watercress at each meal has failed to significantly change urinary nicotine and continine levels, which is thought to be due to minimal inhibition of CYP2A6.[15]

    References
    6.^O'Neill ME, Carroll Y, Corridan B, Olmedilla B, Granado F, Blanco I, Van den Berg H, Hininger I, Rousell AM, Chopra M, Southon S, Thurnham DIA European carotenoid database to assess carotenoid intakes and its use in a five-country comparative studyBr J Nutr.(2001 Apr)
    7.^Bingham SA, Gill C, Welch A, Cassidy A, Runswick SA, Oakes S, Lubin R, Thurnham DI, Key TJ, Roe L, Khaw KT, Day NEValidation of dietary assessment methods in the UK arm of EPIC using weighed records, and 24-hour urinary nitrogen and potassium and serum vitamin C and carotenoids as biomarkersInt J Epidemiol.(1997)
    8.^Saleem A, Walshe-Roussel B, Harris C, Asim M, Tamayo C, Sit S, Arnason JTCharacterisation of phenolics in Flor-Essence--a compound herbal product and its contributing herbsPhytochem Anal.(2009 Sep-Oct)
    9.^Martínez-Sánchez A, Gil-Izquierdo A, Gil MI, Ferreres FA comparative study of flavonoid compounds, vitamin C, and antioxidant properties of baby leaf Brassicaceae speciesJ Agric Food Chem.(2008 Apr 9)
    11.^Bahramikia S, Yazdanparast RAntioxidant efficacy of Nasturtium officinale extracts using various in vitro assay systemsJ Acupunct Meridian Stud.(2010 Dec)
    13.^Chung FL, Morse MA, Eklind KI, Lewis JQuantitation of human uptake of the anticarcinogen phenethyl isothiocyanate after a watercress mealCancer Epidemiol Biomarkers Prev.(1992 Jul-Aug)
    14.^Hecht SS, Chung FL, Richie JP Jr, Akerkar SA, Borukhova A, Skowronski L, Carmella SGEffects of watercress consumption on metabolism of a tobacco-specific lung carcinogen in smokersCancer Epidemiol Biomarkers Prev.(1995 Dec)
    16.^Syed Alwi SS, Cavell BE, Telang U, Morris ME, Parry BM, Packham GIn vivo modulation of 4E binding protein 1 (4E-BP1) phosphorylation by watercress: a pilot studyBr J Nutr.(2010 Nov)
    18.^Yazdanparast R, Bahramikia S, Ardestani ANasturtium officinale reduces oxidative stress and enhances antioxidant capacity in hypercholesterolaemic ratsChem Biol Interact.(2008 Apr 15)
    21.^Casanova NA, Ariagno JI, López Nigro MM, Mendeluk GR, Gette MD, Petenatti E, Palaoro LA, Carballo MAIn vivo antigenotoxic activity of watercress juice (Nasturtium officinale) against induced DNA damageJ Appl Toxicol.(2012 Apr 4)
    22.^Hofmann T, Kuhnert A, Schubert A, Gill C, Rowland IR, Pool-Zobel BL, Glei MModulation of detoxification enzymes by watercress: in vitro and in vivo investigations in human peripheral blood cellsEur J Nutr.(2009 Dec)
    25.^Gill CI, Haldar S, Boyd LA, Bennett R, Whiteford J, Butler M, Pearson JR, Bradbury I, Rowland IRWatercress supplementation in diet reduces lymphocyte DNA damage and alters blood antioxidant status in healthy adultsAm J Clin Nutr.(2007 Feb)
    28.^Wang XH, Cavell BE, Syed Alwi SS, Packham GInhibition of hypoxia inducible factor by phenethyl isothiocyanateBiochem Pharmacol.(2009 Aug 1)