Is it a rumor that spinach is high in iron?

We have heard countless rumors and lies since we were little, such as lying will make your nose grow longer, and we were picked up from a trash can, etc. Of course, these have been refuted. But there are some rumors that we still believe, such as "spinach contains high iron content because the decimal point is wrong" - this is a rumor!!!

Are you dumbfounded? Growing up watching Popeye, we were taught to eat more spinach so that we would have more energy. Who would have thought that this was a rumor? So how much iron is contained in spinach? Did we eat so much spinach in vain? Today, let's talk about the iron content of spinach.

01. Is it a rumor that spinach is high in iron?

I wrote an answer about immunity a few days ago, and several people laughed at the joke that “spinach is high in iron”. I was really shocked.

So I looked up some information! It turns out that spinach really does have a high iron content! This is clearly using one rumor to attack another rumor.

Let’s start with the most common version

Popeye's love for spinach stems from one of the simplest mathematical mistakes in history. Recently, American mathematician Albersman said that a German chemist miscalculated the iron content of spinach, and finally created the myth that spinach can strengthen muscles. In 1870, German chemist Wolf studied the iron content in spinach and other green vegetables. When recording his findings in a notebook, he miscalculated a decimal point, causing the iron content of spinach to be 10 times the actual content. There are only 3.5 mg in 100 grams of spinach, and because of the miscalculated decimal point, this number became 35 mg. It was because of his mistake that the producers of "Popeye" made the animated character like spinach. In the cartoon, Popeye will have infinite power as long as he eats a can of spinach. In his new book, "The Half-Life of Truth: Why Everything We Know Has an Expiration Date", Albersman tells how mistakes made in scientific research gave birth to myths that we are familiar with. Take Wolfe's mistake as an example. If the 35 mg content is real, consuming a large amount of spinach is equivalent to eating a small paper clip. Wolfe's mistake caused the animation staff to mistakenly believe that spinach has magical health benefits, so they let their Popeye eat spinach to increase strength. It is believed that the appearance of Popeye increased the consumption of spinach in the United States by one third. In 1937, Wolfe's mistake was discovered and corrected when someone verified his calculations. However, people still believe that spinach is one of the vegetables richest in iron, which may be due to the influence of Popeye. It is a misunderstanding that spinach is high in iron-News Channel-Hexun.com

I believe that many people have seen this popular science content and have since been convinced that the high iron content in spinach is a rumor, and that this is because the scientist made a mistake in the decimal point.

02. What is the truth?

First, there is no evidence that someone put the wrong decimal point. The evidence about 1870 has been lost in history, and there is no way to find the original text (it may even be fabricated, which is a problem if you don't attach references).

Fortunately, we can find some earlier literature. At least 50 years before Popeye was filmed, scientists already had a relatively accurate grasp of the iron content in spinach!

Regarding the issue of spinach content, there was indeed a difference. The two research groups published an article in JBC, but it was definitely not at the level of a decimal point, but rather a correction to the measurement method ( Bibyridine Method )

In 1934, Sherman published a study stating that 100g of spinach contained 53 mg of iron.

Later, another group of researchers, Kohler, pointed out that the iron content in dried spinach is only 35.2 mg.

It can be seen that the difference between the two is not to the decimal point level.

Second, spinach really has a lot of iron! I have combined several sources to give a comparison of the iron content of common vegetables. You can get a feel for the iron content of spinach.

Among these common vegetables, have you felt the power of spinach?

In addition, the iron content of each part of spinach is compared

It should be noted that although spinach has a high iron content, it is not the highest. For example, black fungus has a higher iron content than spinach.

References for this article:

1. Two JBC articles on the iron content of spinach. Note that the second article mentions "modification"

2. Sherman WC, Elvehjem CA, Hart E B. Further studies on the availability of iron in biological materials[J]. Journal of Biological Chemistry, 1934, 107: 383-394.

3. Kohler GO, Elvehjem CA, Hart E B. Modifications of the bipyridine method for available iron[J]. Journal of Biological Chemistry, 1936, 113: 49-53.

4. Determination of the iron content of several vegetables, in which the later one was calibrated based on the first one

5. Li Hongshuang, Sun Chengfeng. Study on the variation of mineral composition of quick-frozen vegetables[J]. Food Science, 2005, 26(5): 85-88.

6. Wang Qingwei, Wang Xin, Zhai Hongju. Determination of trace element iron in vegetables[J]. Songliao Journal (Natural Science Edition), 2000, 4: 018.