Ipomoea aquatica is know as morning glory or water spinach in English and ong choy in Chinese. It is an aquatic plant that grows wild beside waterways and fresh water swamps in many of the world’s tropical and sub-tropical regions. Water spinach is from the Convolvulaceae botanical family and its plant has bell shaped flowers, very similar to the flowers of the sweet potato plant, which is also from the Convolvulaceae species. Despite its true botanical connection, water spinach is considered a leafy vegetable because it is cooked and used in the same manner as Cruciferous vegetables, such as kale and arugula. This plant has a high amount of phenolic compounds, which makes it extremely nutritious, antioxidant, and disease preventative.
Water spinach has long, hollow stems with narrow spear shaped or wide triangle leaves, about 4-6 inches long. There are a number of different varieties which include a white stemmed variety known as pak quat and the more common green stemmed genus called ching quat. There is also a purple stemmed variety. The origin of water spinach is unknown although some experts believe it originated from Africa, however it is most prevalent in Southeast Asia and Australia. Water spinach also grows wild in subtropical parts of the USA, such as Florida and Texas, although in most US states its cultivation, sale and the importation of seeds are prohibited as it is considered an invasive species. In fact water spinach is listed on the United States Department of Agriculture website as a noxious weed. Although It can be found at Asian markets in California, water spinach cannot legally be transported out of state.
Traditionally in Asia water spinach was considered a cheap and nutritious food for the masses, mainly because it grows rampantly and is available year round. It is also very easy to cultivate compared with other vegetables. In Asian cooking, both the stems and leaves are consumed. Water spinach has a delicate, slightly sweet flavor, similar to spinach, and a great crunchy texture that blends well with the sweet, aromatic and spicy flavors of Asian cuisine.
In Vietnamese cuisine water spinach is known as rau muong. It is added to soups and used in stir fry’s, which usually involve garlic, ginger and chili. In Indonesia water spinach or kang kung, as it is known, is an ingredient in the popular dish Gado gado salad. The salad is prepared with various green vegetables which are tossed with a spicy peanut dressing made with peanuts, chili, palm sugar and tamarind. In Thailand this vegetable is known as pak bung fadang. It can be seen everywhere from market stalls to five star hotel restaurants. And in the Philippines water spinach (kang kong) is an essential ingredient for the ubiquitous sour fish stew known as sinigang.
Water Spinach and its Nutrition: Like spinach, water spianch is rich in iron, calcium and riboflavin. It is an excellent source of the antioxidant vitamin’s C and A. This plant has numerous carotenoids. Carotenoids are plant pigments which when digested are converted into vitamin A. The principle carotenoids in water spinach are lutein, lutein epoxide, violaxanthin and neoxanthin. Lutein is important for eye health and research indicates that increased lutein intake may lower our risk of cataracts. Violaxanthin and neoxanthin are two carotenoids which as yet haven’t gotten as much attention as beta-corotene or lutein. However, they are also powerful antioxidants which have anti-inflammatory and anti-cancer properties.
Water spinach has long been used in Southeast Asia as a traditional herbal medicine for the treatment and prevention of ailments, including high blood pressure, diabetes and eye diseases. In recent years researchers have discovered that the leaves and stems of water spinach are high in phenolic compounds (antioxidants).
Researchers in India found that water spinach showed cytotoxicity toward cancer cells, meaning that certain properties in the stems and leaves could destroy cancer cells. The 2005 ‘in vivo’ study on lab rats, concluded that more research needs to be done. Other studies suggest that water spinach should be included in the diet of diabetics because it was shown to inhibit the effect of glucose absorption. Water spinach is also antimicrobial and anti-ulcerogenic, suggesting that it can heal peptic ulcers. Water spinach may also improve acetylcholine levels in the brain. A lack of which is thought to lead to memory loss and Alzheimer’s disease.