Watercress is a popular leafy green vegetable (known as a cruciferous vegetable) packed with nutrients that may have anti-cancer properties. Watercress consumption can also stimulate antioxidant enzymes, which is thought to reduce DNA damage.
It contains the antioxidants beta carotene, zeaxanthin and lutein.
The Research
Benefits
Watercress is a nutrient-dense food. Powerhouse fruits and vegetables are foods most strongly associated with reduced chronic disease risk. According to the CDC’s Powerhouse Fruits and Vegetables list, watercress is ranked number one, with a nutrient-density score of 100 percent (1).
Watercress contains 14.6 mg of vitamin C per cup (34 grams), which is 24 percent of the recommended daily value of this vitamin (2).
Other beneficial nutrients include vitamin A, vitamin E, vitamin K and vitamin B6 (3).
Watercress may protect against oxidative stress. Oxidative stress occurs when there is an imbalance in cells due to either an increase in free radicals and/or a decrease in antioxidants.
Free radicals are unstable atoms that can damage cells, causing illness and aging; antioxidants are man-made or natural substances that may prevent or delay some types of cell damage.
To test this vegetable’s ability to fight oxidative stress, researchers treated mice with different doses of watercress juice (0.5 and 1g/kg body weight) for 15 consecutive days before injecting them with cyclophosphamide to induce oxidative stress.
Intake of watercress prior to cyclophosphamide administration enhanced superoxide dismutase activity — an enzyme that helps break down potentially harmful oxygen molecules in cells; In bone marrow and liver tissues, watercress juice counteracted the effect of cyclophosphamide.
In addition, glutathione balance (a potent antioxidant) rose with watercress supplementation (4).
Watercress may help protect against cancer. Watercress contains compounds called isothiocyanates that have been shown to help the body protect against carcinogens. In particular, phenethyl isothiocyanates (PEITC), have been shown to be most effective.
Many isothiocyanates, both natural and synthetic, display anticarcinogenic activity because they reduce activation of carcinogens and increase their detoxification (5).
Impressive results have been obtained in animal models of lung and esophageal cancer, according to the journal, Drug Metabolism Reviews.
Isothiocyanates found in watercress have also been shown to help prevent colon, prostate and skin cancers.
New research from the University of Southampton in England has revealed that a plant compound in watercress may have the ability to suppress breast cancer cell development by “turning off” a signal in the body. As a result, growing tumors are starved of essential blood and oxygen.
Watercress may help lower high cholesterol levels and triglycerides. The results of an animal study published in Chemico-Biological Interactions showed that supplementation has high hypolipidemic (cholesterol-lowering) activity that may be attributed to its antioxidative potential (6).
In another study, administration of watercress hydroalcoholic extract to groups of hypercholesterolemic rats for 10 days, lowered their serum total cholesterol and LDL-C by 34.2 and 52.9 percent, respectively, while raising the serum HDL-C (good cholesterol) level by 27 percent after 10 days of treatments (7).
HDL is considered “good” cholesterol due to its ability to act as a scavenger, carrying some of the LDL (bad) cholesterol away from the arteries and back to the liver, where the LDL is broken down and passed from the body (8).
While further studies are needed, results so far demonstrate watercress’ cardioprotective potential.
Watercress may help treat inflammatory skin diseases. Inflammatory skin disorders are some of the most common problems in dermatology. Skin inflammation can be acute or chronic and range from skin itching and redness, to eczema, rosacea, seborrheic dermatitis and psoriasis.
In the January 2019 issue of the Journal of Ethnopharmacology, researchers found that topical treatment with Nasturtium officinale (watercress) crude extract leaves reduced inflammation in a contact dermatitis model in mice.
There were no adverse reactions noted (9).
Watercress also has shown to have general anti-inflammatory properties. The anti-inflammatory activity of the hydro-alcoholic extract from aerial parts of watercress was recently investigated.
Oral administration of the extract significantly inhibited paw edema in rats, while topical application reduced ear edema in mice (10). Edema is the medical term for swelling. Body parts swell from injury or inflammation.
Watercress may help prevent age-related macular degeneration (AMD). AMD is a common eye condition and a leading cause of vision loss among people age 50 and older (11).
Researchers believe that due to this vegetable’s lutein and zeaxanthin content (antioxidants that are beneficial to the health of the eyes), eating watercress offers protective properties for visual health. Lutein and zeaxanthin are carotenoid pigments that constitute the main pigments found in the yellow spot of the human retina which protect the macula from damage by blue light, improve visual acuity and scavenge harmful reactive oxygen species (12).
Eating watercress may help keep bones healthy. Just one cup of watercress provides more than 100 percent of the recommended dietary intake of vitamin K.
Vitamin K plays a role in bone metabolism and helps protect bones against osteoporosis (13). Low intakes of dietary vitamin K are associated with an increased risk for fractures.
Side effects
Watercress appears to be safe in food amounts and in supplemental amounts when used short-term. When used in large amounts or long-term, it can cause stomach upset or kidney problems.
Due to its vitamin K content (a vitamin that is used by the body to help blood clot), watercress may decrease the effectiveness of warfarin (Coumadin) — a drug prescribed for people who are at increased risk for developing harmful blood clots.
Recommended dosage
Watercress may be consumed dried (4-6 g/day); fresh (20-30 g/day); or as a juice (60-150 g/day) 14.
Further research is needed to determine the optimal dose when taken as a supplement.
Recap
Watercress is a leafy vegetable that is packed with nutrients and antioxidants which offer several health benefits, including helping prevent certain types of cancer and reducing DNA damage. Rich in antioxidants beta carotene, zeaxanthin and lutein, and vitamins A, E, K and B6, it may also lower cholesterol and triglycerides and treat inflammatory skin disorders and other types of inflammation.
Early studies also show its ability to protect against age-related macular degeneration and osteoporosis.
Like many other vegetables, adding watercress to a healthy diet is the best way to reap its many benefits.
Studies on the efficacy, dosage and side effects of long-term supplement use in humans are needed.