Water spinach is a green vegetable that enhances Asian dishes in particular. It belongs to the genus of the showy vine and can be both annual and perennial. Other names – especially in the culinary field – are phak kwang tung or kangkung.
Here’s what you should know about water spinach
Water spinach thrives mainly in humid locations up to 1550 meters above sea level. The green leafy vegetable probably originated in Asia and is now at home in tropical and subtropical areas. Water spinach belongs to the genus of showy bindweed, which is also known to botanists as splendid bindweed or Ipomoea. The genus includes about 650 different species of plants, including sweet potato, and belongs to the bindweed family. Water spinach thrives mainly in moist locations up to 1550 m altitude. The green leafy vegetable probably originated in Asia and is now at home in tropical and subtropical areas. There it occurs very frequently. While water spinach grows herbaceously on the ground in some locations, it can also float on water in rice paddies, ponds or slow-flowing bodies of water. Thus, it is not only adapted to different locations, but can also cope under changing environmental conditions. The plant can be both annual and perennial. Annual water spinach flowers only once and then withers; farmers must reseed it every year. However, this need not be an economic disadvantage if farmers harvest the whole plant anyway. From perennial water spinach, on the other hand, they can collect only individual leaves. In this case, the plant remains intact and continues to live. It survives for several years in this way. Under good conditions, perennial water spinach can flower and form seeds several times a year. It thus differs from perennial plants, which also live for several years but flower only once a year. The leaf shape of water spinach is elongated, but can vary in individual cases – depending on growing conditions and adaptation. The leaves are either lanceolate or ovate. Sometimes the leaves bear fine hairs that help the plant regulate its fluid balance with the help of evaporation. Water spinach is a relatively undemanding plant and thrives almost all year round, provided temperatures do not drop below freezing. In greenhouses (including cold greenhouses without artificial heating), farmers also grow water spinach throughout the year.
Importance for health
The carbohydrates in water spinach are mainly complex carbohydrates; the human body can digest them only slowly, because enzymes must first break down the individual carbohydrate building blocks. Only then can the digested carbohydrates pass through the intestinal wall into the blood. Complex carbohydrates are thus in contrast to simple carbohydrates such as sugar. These carbohydrates consist only of short chains of sugar molecules – the body therefore hardly has to break them down and can absorb them more quickly. Complex carbohydrates raise blood sugar levels comparatively slowly and keep them constant for longer. Eating water spinach and other foods that contain more complex than simple carbohydrates thus helps prevent diabetes and other metabolic diseases. Some carbohydrates in water spinach cannot be digested by humans. They are dietary fibers that have no nutritional value in themselves. Nevertheless, they are of great importance for the functioning of the intestines: they challenge muscle movements and thus prevent constipation and other digestive problems. The German Nutrition Society (DGE) recommends consuming 30 g of dietary fiber per day. In addition, water spinach contains numerous secondary plant compounds such as chlorophyll. Nutritionists and physicians are still not in agreement about the significance of these substances for the human organism. However, some studies show possible positive effects of secondary plant compounds on health, especially in relation to cardiovascular diseases and cancer. However, these data are not considered to be certain and require more in-depth research in the future.
Ingredients and nutritional values
| Nutritional information |
Amount per 100 gram |
| Calories 19 | Fat content 0.2 g |
| Cholesterol 0 mg |
Sodium 113 mg |
| Potassium 312 mg | Carbohydrates 3.1 g |
| Protein 2,6 g |
Dietary fiber 2.1 g |
Water spinach contains about 48% carbohydrates – including many complex carbohydrates – and 24% protein in dry matter. Thus, 100 g of fresh water spinach contains an average of 3.4 g of carbohydrates and 2 g of dietary fiber. The intact plant consists of 90% water and is very low in calories: 100 g contain only 19-20 kcal. Water spinach is therefore ideal for a calorie-conscious and low-carbohydrate diet.
Intolerances and allergies
A specific allergy to water spinach is very rare and is not one of the common allergies. However, if typical allergy signs such as red skin, hives, swollen skin, eyes, or throat manifest after eating water spinach, medical evaluation is necessary. Intolerances more often manifest themselves in the form of digestive complaints. However, these may also be due to the fiber and complex carbohydrates that water spinach contains. People whose previous diet was deficient in such substances usually have to get used to this change first. However, the digestive system learns to cope with the new food after a short time. Often, therefore, the digestive complaints disappear after about two weeks of regular consumption of complex carbohydrates and dietary fiber (at least 30 g per day). If the person suffers from delicate complaints such as swelling of the esophagus or is not sure, it is better to refrain from eating the water spinach for safety reasons.
Shopping and kitchen tips
In stores, water spinach is also often available under the name Phak Kwang Tung or Kangkung. Asian cuisine makes the most use of water spinach. It is used in numerous dishes, often with other vegetables, but also with rice alone. Fresh water spinach should be stored in the refrigerator. The best place for this is a closed container in the crisper, as the cooling there is ideal for the green leafy vegetable. The leaves tend to wilt quite quickly – which is not only less visually appealing, but also has a negative effect on the ingredients: many vitamins break down very quickly when the uprooted plant is exposed to free air circulation. Sunlight also breaks down some nutrients such as vitamins and alters them on a biochemical level, which biologically inactivates them. Subsequently, they no longer possess the desired health effect for humans.
Preparation tips
Water spinach complements vegetable and rice dishes and is suitable for both steaming and sautéing. In modern cooking, a microwave oven is already sufficient for steaming. To do this, place the water spinach in a cooking bag or microwave-safe container and steam briefly at low power. In a saucepan, cooks steam the vegetables by pouring a small amount of water into the pot and placing the water spinach over it in a strainer or cooking basket. The water spinach must then stand for about a minute and is ready for further use. A simple dish with water spinach consists of rice and steamed water spinach, enriched (depending on the region, season and occasion) with spices as desired. A teaspoon of sesame oil completes the dish.