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Watercress, with the botanical name Nasturtium officinale, is a fast-growing, aquatic or semi-aquatic, perennial plant native to Europe and Asia, and one of the oldest known leaf vegetables consumed by humans. It is a member of the family Brassicaceae, botanically related to garden cress, mustard and radish — all noteworthy for a peppery, tangy flavour.
Nasturtium nasturtium-aquaticum (nomenclaturally invalid) and Sisymbrium nasturtium-aquaticum L. are synonyms of N. officinale. Watercress is also listed in some sources as belonging to the genus Rorippa, although molecular evidence shows the aquatic species with hollow stems are more closely related to Cardamine than Rorippa. Despite the Latin name, watercress is not closely related to the flowers popularly known as nasturtiums (Tropaeolum majus).
Cultivation of watercress is practical on both a large-scale and a garden-scale. Being semi-aquatic, watercress is well-suited to hydroponic cultivation, thriving best in water that is slightly alkaline. It is frequently produced around the headwaters of chalk streams. In many local markets, the demand for hydroponically grown watercress exceeds supply, partly because cress leaves are unsuitable for distribution in dried form, and can only be stored fresh for a short period.
Watercress can be sold in supermarkets in sealed plastic bags, containing a little moisture and lightly pressurised to prevent crushing of contents. This has allowed national availability with a once-purchased storage life of one to two days in chilled/refrigerated storage.
Also sold as sprouts, the edible shoots are harvested days after germination. If unharvested, watercress can grow to a height of 50–120 centimetres (1.6–3.9 ft). Like many plants in this family, the foliage of watercress becomes bitter when the plants begin producing flowers.
In the United Kingdom, watercress was first commercially cultivated in 1808 by the horticulturist William Bradbery, along the River Ebbsfleet in Kent. Watercress is now grown in a number of counties of the United Kingdom, most notably Hertfordshire, Hampshire, Wiltshire and Dorset. The town of Alresford, near Winchester, holds a Watercress Festival that brings in more than 15,000 visitors every year, and a preserved steam railway line has been named after the local crop. In recent years,[when?] watercress has become more widely available in the UK, at least in the southeast; it is stocked pre-packed in some supermarkets, as well as fresh by the bunch at farmers' markets and greengrocers.
In the United States in the 1940s, Huntsville, Alabama was locally known as the "watercress capital of the world". Today, Oviedo, Florida in the United States is known by that title, while Alresford in England is considered to be that nation's watercress capital.
|Nutritional value per 100 g (3.5 oz)|
|Energy||46 kJ (11 kcal)|
|- Sugars||0.2 g|
|- Dietary fiber||0.5 g|
|Vitamin A equiv.||160 μg (20%)|
|- beta-carotene||1914 μg (18%)|
|- lutein and zeaxanthin||5767 μg|
|Thiamine (vit. B1)||0.09 mg (8%)|
|Riboflavin (vit. B2)||0.12 mg (10%)|
|Pantothenic acid (B5)||0.31 mg (6%)|
|Vitamin B6||0.129 mg (10%)|
|Folate (vit. B9)||9 μg (2%)|
|Vitamin C||43 mg (52%)|
|Vitamin E||1 mg (7%)|
|Vitamin K||250 μg (238%)|
|Calcium||120 mg (12%)|
|Iron||0.2 mg (2%)|
|Magnesium||21 mg (6%)|
|Manganese||0.244 mg (12%)|
|Phosphorus||60 mg (9%)|
|Potassium||330 mg (7%)|
|Sodium||41 mg (3%)|
|Link to USDA Database entry|
Percentages are roughly approximated
using US recommendations for adults.
Source: USDA Nutrient Database
Watercress contains significant amounts of iron, calcium, iodine, and folic acid, in addition to vitamins A and C. Because it is relatively rich in Vitamin C, watercress was suggested (among other plants) by English military surgeon John Woodall (1570–1643) as a remedy for scurvy.
Many benefits from eating watercress are claimed, such as that it acts as a stimulant, a source of phytochemicals and antioxidants, a diuretic, an expectorant, and a digestive aid. It also appears to have antiangiogenic cancer-suppressing properties; it is widely believed to help defend against lung cancer. A 2010 study conducted by the University of Southampton found that consumption of watercress may also inhibit the growth of breast cancer. The content of phenethyl isothiocyanate (PEITC) in watercress inhibits HIF, which can inhibit angiogenesis.
Watercress crops grown in the presence of manure can be a haven for parasites such as the liver fluke Fasciola hepatica. Watercress is a known inhibitor of the cytochrome P450 CYP2E1, which may result in altered drug metabolism for individuals on certain medications such as chlorzoxazone.