"The king of all poisons"? "The cramp-causing vegetable"? How did water spinach get its bad reputation?

When it comes to eating vegetables, everyone's first reaction may be healthy and green, but there is a vegetable that has a very bad reputation. Some people even call it the "king of all poisons" on the Internet, and say that eating too much of it can cause cramps, etc. It is water spinach. So, is water spinach really so bad?

Source: pexels

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“The King of All Poisons”? Heavy metals seriously exceeding the limit?

Water spinach, formerly known as water spinach, is mainly divided into two types: dry water spinach and water spinach. It is native to East Asia and is currently grown in central and southern provinces of China, but less in the north. It is suitable for growing in areas with warm and humid climates and fertile soils. It requires a lot of water for growth and has poor cold resistance. However, due to its high requirements for water quality, the cost of aquatic water spinach is high and the yield is small. The water spinach on the market today is basically drought-tolerant.

Source: China Plant Image Database Photographed by Xue Zichao

Water spinach is a shallow-rooted crop with a short growth cycle and fast growth rate . It can usually be harvested in about 20 days, which is why many farmers like to grow it. Such a fast growth rate also proves that water spinach has an outstanding ability to absorb soil nutrients. The title of "King of All Poisons" on the Internet comes from this, saying that water spinach can absorb heavy metals in the soil. But is this really the case?

First, the ability of vegetables to accumulate heavy metals is not only related to their morphological structure, but also to the distribution of their root systems and their absorption capacity . In fact, water spinach is not very good at absorbing heavy metals. Secondly, the heavy metal content of vegetables is closely related to the ecological environment of their production areas . If the soil and water quality of the production environment meet the national healthy production standards, then the vegetables and fruits grown will generally not have excessive heavy metals; if the planting environment conditions do not meet the standards, then even vegetables with weaker heavy metal absorption capacity may easily exceed the heavy metal standard.

The root system of water spinach

Source: China Plant Image Database Photographed by Zhu Xinxin

The "National Food Safety Standard Limits of Contaminants in Food" issued by my country on June 30, 2022 clearly stipulates that the maximum limits of the four major heavy metals, lead, cadmium, total mercury, and total arsenic, in fresh leafy vegetables are 0.3, 0.2, 0.01, and 0.5 mg/kg, respectively. The Guangzhou Academy of Agricultural Sciences once tested the heavy metal content of dry-grown water spinach produced in farmland with qualified environmental quality. The results showed that the contents of the above four heavy metal elements in water spinach did not exceed 0.028, 0.036, 0.0024, and 0.032 mg/Kg, respectively, which are far below the national standard limits. This shows that as long as the water spinach is purchased from regular channels, there is no need to worry about its health risks, and the title of "King of All Poisons" is naturally a rumor. Moreover, the vegetables on the market today can only be sold after passing the inspection of the relevant departments, so everyone does not have to worry too much about safety issues.

Source: Photo by Zhou Hongyi from China Plant Image Library

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Is water spinach really a “cramp-inducing vegetable”?

It is often said that water spinach is a "cramp vegetable" and eating too much can easily cause calcium deficiency in the body, which can cause a series of symptoms such as cramps, back pain and leg pain. Today, the editor is here to dispel the rumor. This statement is not accurate. The most likely cause of this symptom is that water spinach, spinach and other vegetables contain high levels of oxalic acid, which will combine with calcium in the body to form calcium oxalate precipitation, causing calcium loss in the body, which may affect calcium absorption.

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However, this effect is minimal. For the general population, except for those who are calcium deficient, it will not cause cramps, back pain and other related symptoms. Here is a tip for everyone. If we blanch the water spinach before cooking, we can remove 50%-80% of the oxalic acid, so we don't have to worry about affecting the absorption of calcium.

It is worth mentioning that the calcium content of water spinach itself is very high. Every 100 grams of water spinach contains 99 mg of calcium. Therefore, as long as the cooking method is correct, eating water spinach can actually supplement calcium. The saying that it is a "cramp-inducing vegetable" is naturally nonsense.

Moreover, the nutritional value of water spinach is very high, rich in protein, fat, calcium, phosphorus and other nutrients. It is worth mentioning that the sugar content of water spinach is as high as 4%, and the protein content is 2.8%, which are three times and five times that of tomatoes respectively. In addition, water spinach also contains a certain amount of dietary fiber , which can promote intestinal peristalsis and play a positive role in preventing and treating constipation and reducing the risk of intestinal cancer.

Source: unsplash

Finally, how should we eat water spinach? First of all, as mentioned above, blanching before eating can avoid calcium loss; secondly, except for the root, its leaves and stems are edible, and the dietary fiber content of the stems is higher; because water spinach has a high dietary fiber content, eating too much may cause a certain burden on the stomach and intestines, so for patients with symptoms such as gastric ulcers, chronic gastritis, and duodenal ulcers, it is still better to eat less water spinach.