THE CONVERSATION: Do carrots really improve your night vision? Six enduring diet myths, debunked

One of science’s main roles in society is to probe extraordinary claims, separate fact from fiction, and set the record straight. But it does not always succeed. Indeed, sometimes the exact opposite happens.

“Science” itself can sometimes take things out of context, and present half-truths which, repeated over generations, eventually come to seem like total certainties. These ideas do not necessarily take root because they are true, but because they sound good, seem like common sense, and often carry the authority of being linked to an eminent name.

I am not talking here about the fake news or outright hoaxes that proliferate on social media, but phrases and ideas with historical – and even academic – pedigree that have been mistakenly adopted as unquestionable truths.

One of the best-known examples is the phrase attributed to Ancient Greek philosopher and physician Hippocrates: “Let food be thy medicine and medicine be thy food”. While frequently attributed to him, there is no firm basis for this.

Despite its dubious origins being revealed years ago, the phrase continues to feature in articles and speeches – likely because it is shrouded in apparent wisdom.

Something similar applies to the saying “you are what you eat”. Today it is often treated as an indisputable truth, but its original meaning was philosophical, not physiological.

The phrase formed part of a reflection on the importance of the material dimension of human beings put forward by the 19th century German philosopher Ludwig Feuerbach, to challenge those who attached importance only to the soul or the mind.

With this famous phrase, Feuerbach was advocating for social justice from a political and anthropological perspective – not making a lifestyle recommendation.

The case of spinach and iron is curious on two fronts. For years, it was claimed that this vegetable’s mistaken reputation as an iron-rich food was due to a transcription error involving a misplaced decimal point in the early 19th century. The story was so widely accepted that it has been repeated time and again in books, articles and lectures.

But the supposed decimal error also appears to be untrue. Not only was an incorrect idea about spinach widely spread, but the explanation of this information’s origin was also false.

Another modern myth is the claim that eating carrots improves night vision. Carrots are a source of vitamin A, a nutrient that plays a role in visual function – but that doesn’t mean they will miraculously make you see in the dark.

The spread of this idea was closely linked to British World War II prop