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Popeye's spinach story rich in irony

If you simply believe whatever you read you will end up in a spot of bother. And when it comes to the facts about spinach, even Dr Karl was fooled.

If you are a student of popular culture, you would probably have heard of Popeye. He's that pipe-smoking sailor-man, who has very high moral standards and speaks in very mangled English.

When Popeye's in a spot of bother, he simply eats a tin of spinach (rich in iron) and instantly grows enormous biceps and uses his new-found strength to overcome his enemies.

But if you look more closely, you will find a good example of what can go wrong if you blindly believe whatever you read.

This is the mistake that I made way back in 1981, when I read an article, entitled 'Fake', in the British Medical Journal.

Dr TJ Hamblin, a haematologist, wrote about many fraudulent activities in science and medicine. Just one-third of a page, out of his four-page article, was about Popeye, spinach and iron.

Dr Hamblin wrote that spinach was so low in iron, that Popeye would have been better off eating the can if he wanted some iron. Dr Hamblin went on to explain that the problem began in the 1890s, when some German scientists analysed the iron content of spinach correctly.

Unfortunately, when they wrote the result in their paper, they put the decimal point in the wrong place and accidentally published a result that was 10-times too large.

This result was corrected in the 1930s, but by this time, thanks to the good — but false — publicity about the nutritional importance of spinach, its consumption had increased by 30 per cent during the 1920s and 1930s.

This all sounded perfectly reasonable, and so I wrote this up as a short story for my ABC pre-recorded program, Great Moments in Science.

Unfortunately, Dr Hamblin had made a mistake, and I had spread this mistake, simply because I had not checked Dr Hamblin's paper.

You see, back in the 1980s, I had not realised that the Christmas issue of the British Medical Journal was their comedy issue, when they let their hair down and had some fun.

I didn't know that the British Medical Journal had approached Dr Hamblin and had asked him to write a light-hearted story.

Dr Hamblin later said that, very unusually for a peer-reviewed journal, he didn't have to provide references. He could be a little 'loose' with the facts.

The way I found this out was that I read a paper by Dr Mike Sutton, in the Internet Journal of Criminology.

His paper was entitled 'Spinach, Iron and Popeye: Ironic lessons from biochemistry and history on the importance of healthy eating, healthy skepticism and adequate citation'.

It took Dr Sutton many, many weeks of doggedly searching through and reading academic and nutrition journals dating back to the 1920s, as well as the complete set of the comic strip cartoons featuring Popeye between 1928 and 1935, before he could write his 13,000-word analysis.

First, the German scientists who analysed plants in the early days were Emil Theodor von Wolff (1818–96) and Gustav von Bunge (1844–1920). There is no record of their having made the mistake of shifting the decimal point.

Second, on the 3rd of July 1932, Popeye eats some spinach because 'Spinach is full of vitamin A an' tha's what makes hoomans strong an' helty'.

This is the first time Popeye eats spinach. Note that there is no mention of iron.

Third, in 1934, some chemists from the University of Wisconsin did analyse several plants for their iron content. In their paper, they confused the iron content of fresh and dried spinach. Dried spinach would have lost its water, and would appear to be about 10–20-times more concentrated in iron than fresh spinach. This error was corrected in 1936.

Fourth, the consumption of spinach in the USA had already increased massively between 1915 and 1928, long before Popeye had begun to eat it in 1932.

Fifth, spinach actually does contain about 50 per cent more iron than meat does. However, only about half of this iron in spinach is easily available to enter the human body. But there's still lots of iron in spinach.

However, thanks to the article by Hamblin in 1981, many, many later writers were fooled. They have quoted that Popeye was wrong about spinach being rich in iron, and that it's all due to sloppy German scientists of the 1890s putting the decimal point in the wrong spot.

And I was fooled as well, and so were my listeners.

Popeye would claim that he was 'strong to the finish, 'cos he eats his spinach'.

But in the land of science, if a paper doesn't have any references, the words on the page carry less weight than the paper itself.

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