What gives a super strength to Popeye the Sailor Man, cartoon character popular in the 1930s?

The commonly accepted version of events states this portrayal was based on the popular misconception that spinach is high in iron that makes the body stronger. In 1870s, German scientist Emil von Wolff misplaced a decimal point in a measurement of spinach's iron content, leading to an iron value ten times higher than it should have been, and this faulty measurement was not noticed until the 1930s.