What most people know about water chestnuts (Eleocharis Dulcis), sometimes more specifically called Chinese water chestnuts, are the basics: they’re white, have a crunchy texture and a fresh mild taste, and are often used in Chinese cooking. In the West, most who use the small, round ‘corms’ (short, underground, slightly bulbous stem bases) in their culinary endeavours buy them either whole or sliced in a can.
Water chestnuts are perennials from a family of plants called sedge, a type of marshy grass with the edible part appearing at the bottom very much like a real chestnut in shape and colour. From the Cyperaceae family, these aren’t actually nuts but an aquatic vegetable. Each has a similar size and mildly sweet apple‐coconut flavour.
Somewhat subdued into blandness when canned, fresh water chestnuts are both sweeter and more firm. Usually available in specialty groceries or supermarkets, they should be washed thoroughly and peeled with a sharp knife, especially if to be eaten raw. At this point, adding a few drops of lemon juice keeps them from turning brown when steamed or sautéed. Once peeled, they'll only remain fresh in water that’s changed daily for two to three days.
Because they’re so popular in tropical countries like Thailand, Vietnam, China, and Japan as well as Australia, water chestnuts are often rotated with rice in paddy fields. Whether thinly sliced in soups, minced as an egg roll ingredient, or sautĕed in a stir fry with snow peas, coconut oil, and ginger, water chestnuts remain crispy even after cooking. They’re the main ingredient in a noted Thai dessert, tabtim krob, and in the West they’re sometimes wrapped with bacon strips as an hors d’oeuvre. In Indonesia they’re blended into a drink.
Chinese water chestnuts shouldn’t be confused with a completely different species, the European water chestnut of the genus Lythraceae. Also called water caltrop (trapa natans) or horned chestnut, this aquatic plant was imported to the U.S. from Asia in the early part of the 20th century. Because of their thorny spikes and invasive nature (not to mention toxins) this plant is the bane of the east coast tourism trade, so selling any type of water chestnut plant species is reportedly banned from most of the Southern states, including Maryland.
While water chestnuts don’t have an overwhelming amount of detailed nutritional information, they do seem to have a reputation in traditional Asian and aboriginal medicine. They’ve been ground into powder, juiced, sliced, boiled, and eaten raw, steamed, or steeped in rice wine and used as a curative and food supplement.
Drinking water chestnut juice has been touted as a way to alleviate nausea, relieve suffering from jaundice, and detoxify the body from impurities. Making the powder into a paste is still used as a remedy for inflammation and is said to be useful, stirred up in water, as a cough elixir and for easing patients with measles.
Nutritionally, water chestnuts provide 10% each of the daily recommended value in vitamin B6, potassium (350 to 360 mg per ½ cup), copper, riboflavin, and manganese, with a respectable array of smaller amounts of other vitamins and minerals, as well. The corms are a rich source of carbohydrates, which relates itself in a starchy texture. Fibre is another ingredient in very good supply, which is effective for keeping your system running smoothly. However, water chestnut has no cholesterol to speak of or vitamin A at all. Fresh raw water chestnuts contain slightly more fat than the canned variety, but it’s the good kind.
Studies have found water chestnuts to contain flavonoid antioxidants. Early aboriginal medicine men crushed the outsides of the bulb for wound application and healing, which science now knows releases antimicrobial effects. Inside water chestnuts are an antibiotic compound called ‘puchin’ which acts in immune function like penicillin.