In 1870 Erich Wolff was studying the iron content in different foods and mismeasured the iron content in spinach. (There's a legend about a misplaced decimal point that seems to be a myth, but his research did lead to incorrectly high scores for spinach and other vegetables.)
Then a few decades later, the newspaper strip Thimble Theatre became a big hit because of a side character, a sailor named Popeye. Popeye could gain tremendous strength by... rubbing a magic chicken.
The source of Popeye's strength soon shifted to spinach, though. And the subsequent cartoons solidified the spinach = superstrength as a core aspect of Popeye's character.
Why spinach? Because people believed spinach was very healthy for you because of the faulty measurements earlier.
Then a few decades later, Popeye cartoons were very popular in Japan, just as videogames were beginning to be a thing.
While Toru Iwatani was designing Pac-Man, he was inspired to include the power-pills because of Popeye's spinach.
Shigeru Miyamoto included the hammers in Donkey Kong (which was originally supposed to be a Popeye videogame but the license issues never got sorted out) and mushroom in Super Mario Brothers, again being inspired by Popeye's spinach.
@nickwedig Non-games related, Popeye is also why we have the anime One Piece, which is essentially Popeye fanfic
(powers from fruits, sailors, inflating arms, that arm spin thing, those laughs, in the original concept the Sea Hag from Popeye was there, etc)
Thanks, scientific blunder!
@nickwedig “Popeye could gain tremendous strength by… rubbing a magic chicken.”
Probably wise they changed that or comic history could have taken a very different and wildly innuendo-ridden path.