Spinach, it turns out, is not an especially good source of iron. As the story goes, people believe it’s a good source of iron because of a misplaced decimal point in a publication in the 1930s, reporting the iron content of spinach as ten times its actual level. But this story is itself apocryphal, as Ole Bjørn Rekdal wonderfully narrates in a cheeky and insightful piece in the most recent Social Studies of Science, Academic Urban Legends.
Rekdal traces the origins of the spinach-decimal-point myth and uses the occasion to catalog bad citation practices, including citing secondary sources for a point made by an original source without verifying the original source, citing an original source instead of a secondary source but relying on the secondary source’s interpretation, and more. Rekdal also traces the urban legend that most academic papers are never cited back to a 1980s study that actually found no such thing. I highly recommend the entire short piece, it’s funny and surprising throughout. For example, Popeye never claimed that spinach made you stronger because it had a lot of iron, and Popeye’s creator apparently had vitamin A in mind instead!