Carrots Help You See in the Dark
"The claim that eating lots of carrots significantly improves your night vision."
Not folk wisdom, deliberate wartime propaganda. In 1939 the RAF began using Airborne Interception radar, letting pilots find enemy bombers in total darkness, a secret Britain badly wanted to protect. Britain's Air Ministry fed the press a cover story instead: night-fighter ace John "Cat's Eyes" Cunningham owed his kills to eating carrots. Posters followed, "Carrots keep you healthy and help you see in the blackout," genuinely useful home-front messaging doubling as cover for the radar secret. The myth outlived the war by decades.
Myth vs. FactCarrots contain vitamin A, which supports normal eye function, but no amount of carrot-eating gives meaningfully enhanced night vision. The myth was a deliberate cover story, not a folk misunderstanding.
Sources: British Air Ministry WWII press campaign; documented via Smithsonian Magazine and BBC Science Focus.