Like with the horizontal-vertical illusion, we're not sure why this is, but it's possible that we conflate bitterness and physical sharpness because they can both be signs of danger.
Past studies often conflated general communication, in which individuals extract meaning from signals sent by other individuals, with language's more specific, flexible and open-ended system.
This myth stems from conflating fruit juices - which can raise blood sugar levels because of their high sugar and low fiber content - with whole fruits.