Over at Jayson Lusk's blog, this post about a hard-to-kill food myth about iron in spinach got me thinking about the various myths we hold about food, fitness and health, and how difficult it can be for the truth to win out over lies.
Perhaps this is because some food myths have more than just one lie protecting them. With the "spinach is an excellent source of iron" myth, there are--believe it or not--multiple nested lies. Here's the first:
The myth from the 1930s that spinach is a rich source of iron was due to misleading information in the original publication: a malpositioned decimal point gave a 10-fold overestimate of iron content [Hamblin, 1981]. Once a paper with misleading information has been published, it is almost impossible to stop citation. (pp. 448–449, emphasis added) 
How is this a lie? Because the story about the misplaced decimal point isn't true. There never was any such decimal point error made! And yet through a series of unusual coincidences, this "falsehood about a falsehood" was repeatedly cited in both academic journals and general media reports.
It gets worse. Dr. Terry Hamblin, the accidental architect of our first myth, also perpetuated yet another myth--one that's found its way into our modern popular culture: that "Popeye was created in order to promote spinach for its iron content." Here's the real truth:
According to Sutton (2010a: 13–14), Elzie Crisler Segar had an entirely different nutrient, vitamin A, in mind when he invented Popeye and contributed to a massive increase in spinach consumption in the United States during the 1930s.
Today, of course, we know why spinach is a poor source of iron, and it's not because spinach doesn't contain any. It does! Rather, it's because the human digestive system simply cannot absorb the iron present in spinach. 
So, what we have here is a myth inside a myth, inside another myth--which brings us, in a roundabout way, to the truth. Sort of.
This isn't to criticize Dr. Hamblin, who, from what I've read about him, strikes me as a genuinely good guy who gladly and sincerely owns up to his errors.
Nevertheless, the spinach myth offers us an intriguing example where scientists weren't just wrong: they were wrong about how they were wrong. And then wrong about how they were wrong about being wrong. And after multiple academic journals as well as the general media propagate this myth into the collective consciousness of, well, everyone, it becomes nearly impossible to set things right.
Which brings up a logical question: what other myths have we been fed? Sure, the myths about spinach turned out to be more or less harmless, but it's easy to think up several food and health myths that were once widely considered "true" but are now thoroughly debunked--and with far from harmless outcomes. Some examples:
* Our "food pyramid" should be built on mostly grains and carbs.
* Dietary cholesterol is a major driver of blood serum cholesterol.
* Eggs are bad for you.
* Vaccines cause autism.
* Margarine is better for you than butter. 
I can add to this several politicized food myths that I've sought to help debunk myself here at Casual Kitchen. For example, the myth that there's logic to banning large sodas. That we're running out of food. That locavorism is good for the environment. That "never from concentrate" orange juices are natural and not heavily processed. That vegetarians are Nazis looking to take away your meat. And so on. Finally, Casual Kitchen's core principles are based on debunking the ludicrous and dangerous myth that healthy food has to be expensive.
One final thought: These are just the myths we now know are myths. What other things do we currently "know" to be true now that haven't yet been debunked? What things do we confidently assume today that just haven't yet been outed as myths? Come back in twenty years and I'm guessing you'll have a list several times as long as the one above.
Think about that for a moment or two and tell me that's not incredibly sobering.
Readers, what do you think? I want to know.
1) The academic paper that’s the source of the italicized quotes above is entertaining, and very much worth reading in its entirety. I'd like to thank Jayson Lusk for pointing me to a sobering look inside the world of academic studies and how they often--inadvertantly or otherwise--propagate misinformation.
2) Don't take this to mean you have to stop eating spinach! You may not get much iron, but you can get many other nutrients from it. In fact my own eye doctor wife recommends spinach (as well as other leafy greens like kale, collard greens or swiss chard) to her patients for good long-term eye health.
3) The butter/margarine myth is a fascinating special case. It started out as "butter is better for you than margarine"--a true statement that was later debunked, and then still later, undebunked.
How can I support Casual Kitchen?
Easy. Do all your shopping at Amazon.com via the links on this site! You can also link to me or subscribe to my RSS feed. Finally, consider sharing this article, or any other article you particularly enjoyed here, to Facebook, Twitter (follow me @danielckoontz!) or to bookmarking sites like reddit, digg or stumbleupon. I'm deeply grateful to my readers for their ongoing support.