Carrots Really Do Help Your Vision
Carrots do have a relationship with good eyesight, but it's not as simple as cramming yourself with as many as possible and waiting for 20/20 vision. Carrots include beta-carotene, which helps produce vitamin A, a key ingredient in a healthy, functioning eye. But vitamin A is useful for maintaining eye health, avoiding cataracts, and slightly improving night vision — not for suddenly becoming a cat.
Interestingly, this tale didn't exactly come from old wives at all. Scientific American reports that it was made up by the UK Ministry of Food during World War II to explain the highly successful night missions made by British pilots (which were actually thanks to some sophisticated new technology the government didn't want to make public).