No, this is not so. The iron in spinach is a form that humans do not absorb well.
Spinach and Iron, an Old Myth
My Mom used to tell me this to encourage me to eat my spinach...which I hated! But dear old Mom was wrong.
Spinach indeed contains a lot of iron, but the iron is in a form that your body cannot absorb, and it just passes right through you.
Dietary iron comes in two forms. There is heme iron, which is found only in animal products---meat, poultry, and seafood. Then there is non-heme iron which is found in many plants. Your body readily absorbs heme iron and can use it for making red blood cells and other needs. Non-heme iron, in contrast, is very poorly absorbed so the body cannot use it. To make things worse, spinach contains a lot of oxalic acid, which further inhibits iron absorption. So sorry Mom, I am not going to eat the spinach!
Popeye and the Decimal Point—Another Myth!
In the late 19th century a German scientist was analyzing vegetables for nutrients—this part is true enough. The myth has him misplacing a decimal point in his report and over reporting the iron content of spinach by a factor of 10. The myth goes on to say that this seemingly high iron content is why the creator of Popeye chose spinach as Popeye's strength vegetable. Finally, the myth claims that Popeye's use of spinach caused real world spinach sales to increase by one-third.
The reality is that the scientist had analyzed the iron in dried spinach, which caused an over-reporting of the iron compared to fresh spinach, by a factor of about 10 as it turns out. A later writer attributed this to a misplaced decimal point which would give a factor of 10 error, but there's no evidence that there ever was a misplaced decimal point, just the mistake of using dried instead of fresh spinach. As to why Popeye depends on spinach, it's not the purported iron, which is never mentioned. What is mentioned in one strip is vitamin A. Popeye himself says “spinach is full of vitamin A an’ tha’s what makes hoomans strong and hefty.” And indeed, spinach is an excellent source of this vitamin. As for increased spinach sales, that's not backed by evidence, but who knows?
Vegetarians and Iron Deficiency
Because heme iron is found only in animal flesh, and the non-heme iron in other foods is poorly absorbed, vegetarians and vegans can easily develop iron deficiency anemia. With careful diet planning and/or supplements this can be avoided.
Here are Some More Nutrition-Related Myths for You!
All eggs are not nutritionally equal!
Raw milk? Sorry, no nutritional benefit.
