Is Popeye eating the wrong vegetable?
Spinach makes you stronger…
Or so Popeye thought.
There is a current debate going on amongst academics (with apparently too much time on their hands!) about a misplaced decimal point in the original research that cited spinach as a great source of iron.
Dr Mike Sutton has written an analysis about the history behind Popeye’s adoption of Spinach.
He then looks at the claims that Popeye was responsible for a 33% increase in USA Spinach consumption in the 1930s
This is a great piece that should be read by all undergraduates about why Statistics do matter but their interpretation must be relevant and taken in context.
“Socially embedded codswallop”
Sutton’s examination of the evidence is quite thorough and it shows how quoting “facts” or journal articles without reference, can quite easily then become “socially embedded codswallop”.
Spinach is one of several “superfoods” that are quoted as having special values, mainly because of its iron content”. In fact E.Segar (Popeye’s creator) chose Spinach because of its Vitamin A content, rather than its iron content.
Iron content
Spinach is a source of non-heme iron, which is usually found in vegetable sources. Unlike heme iron found in animal products, non-heme iron is not as easily absorbed by the body.
That is because Spinach also contains oxalic acid (sometimes referred to as oxalate). Oxalic acid binds with iron, hence inhibiting its absorption.
The iron content changes with cooking too. According to the USDA National Nutrient Database, one cup of cooked spinach provides ~3.5mg of iron whereas a cup of raw spinach only contains 1 mg of iron.
So, Spinach does contain Vitamin A, and some degree of iron, but isn’t a substitute for other meat and fish sources of iron.
The take home message here is NOT “Spinach is bad for you”.
Instead, it is check the evidence, and put stats into context.
Thanks to Anton Parker for the tip (one of the aforementioned Academics with too much time on their hands!)
I’m not sure about having too much time on my hands I actually conducted the myth busting after-dark and in my own time. I think there might be something useful to learn from the spinach decimal point error myth however because it was used extensively by academics (who credulously believed it was true) as an example of the need to check your sources. And yet – with the greatest of irony – that’s exactly what they failed to do in their citing of the myth. I suspect the spinach myth has some very powerful ingredients that might be worth a closer look. If I were a government looks at ways to create powerful propaganda the essential components of such braced-myths would probably be worth studying. Mike Sutton
Hi Mike,
thanks for your comments and the original inspiration. Of course the media are always looking for a story and the “latest” findings. Or for a minor study with poor reaearch base to be extrapolated into “proving expets wrong”.
One problem for us not in Academia, is having access to the full research piece, not just the abstract. I always try to look at the research design. Stats are not my big strength to check.
Popeye was a childhood hero of mine. At the time fresh spinach was only available in season. Instead we used to have the tinned puree option. Not sure it is widely available now. The connection to power food was an inspiration to eat food that could make you big and strong. The other aspect was eating as a family at regular times and highlighting the social side to food.
Much is made of the chemistry of food but not so much of the other aspects found in Chinese cooking in particular. Colour, texture, taste, sour, sweet, bitter, hot and salty.
I see converts to a special diet ignore these other aspects of ENJOYING! food. As with other aspects of training if there is no joy it’s unlikey one will stay with it.