Tuesday, July 12, 2016

Popeye's Spinach

The other day Ward was reading something and called out, "Hey, listen to this. You know how Popeye eats spinach and gets really strong because of the iron in it? Well that portrayal happened because of a simple mistake." He proceeded to tell me that when the nutritional value for spinach was first published in the 1870's, there was a problem with a decimal point. That ended up with the belief that spinach had 10 times more iron in it than it really had. The mistake wasn't figured out until much later.

I thought that was pretty interesting and I would share it with you here on my blog. And that's where the problems began. I did a little googling and found the same story in many places. In fact, it's such a great story that it has been repeated for decades. But no one seems to have ever seen the original paper where this mistake was made. Mike Sutton published extensive research he did on the story in Best Thinking Science. After a lot of investigation, he could find no evidence that the misplaced decimal ever happened.

What about Popeye? Did the misplaced decimal story mislead him into eating spinach for strength? Well, it turns out that when he first ate it, he touted its Vitamin A properties instead of iron content.

Nevertheless, his love of spinach made it the third favorite food among children at one point and consumption of spinach went up in the 1940's when Popeye was in his heyday.

So how much iron does spinach actually have in it and is it any better than other foods as a source of iron? One cup of raw spinach (30 grams) contains 5% of the RDA for iron (which by the way is the same amount of iron in Peppermint Pattie.)  Of course, if you are eating it cooked you are likely to eat more. However, spinach also contains oxalates which bind to the iron and make it hard for the body to absorb. So generally, animal sources of iron are easier for the body to use. However like all leafy greens, spinach good for you for a lot of reasons.

So what conclusion can we draw from all of this? Once again, you can't believe everything you read.

Note: I did reading on this about a week before I wrote it. When I tried to relocate sources for some of the things I had written down, I couldn't find them all again. Therefore, I tried to summarize the topic without too many specifics when I couldn't find the sources. Come to think of it, this might be how some internet rumors get started :)