Because of the conflict, meat was in short supply. Politicians settled on iron-rich spinach as a substitute and recruited Popeye, legendary consumer of tins of the stuff, to their campaign. The result of the cartoon star’s propaganda drive was an amazing 35 per cent increase in consumption.

A statue in Crystal City, Texas, the self-proclaimed “world capital” of spinach, celebrates his success. There is just one small problem with this tale of healthy eating. While spinach is a high-fibre no-fat food, rich in vitamin C and other goodies, it cannot supply the iron found in red meat.

Anyone wanting muscles of Popeye proportions should stick with trying to squeeze open the tins and forget about consuming the contents.

Popeye’s claim to be “strong to the finich, cause I eats me spinach” turns out to be based on a blunder made by German food scientists working in the 1890s.

Details are vague, but researchers investigating the mineral content of vegetables wrote down the wrong result for the Sailor Man’s favourite tonic. They inadvertently credited the plant with 10 times more iron than it contains. (And more recent research reveals that even that is in a form which is difficult for the body to access.) They put their mistake right in the 1930s, though it took a long time for the result to cross the Atlantic. Perhaps the Germans took a perverse pleasure in knowing their enemies were consuming vast quantities of the dark green stuff.

The US government would have been better off trying to persuade people to eat more oily fish, dried fruit, eggs, or nuts and seeds. Prunes, for example, are a good source of iron, though they do have their disadvantages. And blackstrap molasses is also recommended.

Of course, “I’m strong to the finich cause I eats my blackstrap molasses” doesn’t have quite the same ring to it.