From apples and carrots to breakfast and 10,000 steps, how folklore, wartime propaganda and marketing helped shape the health advice we live by.
You wake up and remember that you should probably eat breakfast. Your smartwatch tells you that you are 3,000 steps short of your daily target of 10,000. You reach for an apple because, apparently, it keeps the doctor away. And somewhere in the back of your mind, you remember that carrots are supposed to help you see in the dark.
We follow health advice every day without necessarily asking where it came from or whether the evidence supports it. Questioning these familiar rules can even seem unnecessary. After all, they sound like the sort of recommendations that must have originated in laboratories, been tested by scientists and eventually passed on to the public.
But how many of these rules actually began with scientific research?
Some have a basis in sound nutritional advice. Others grew out of folklore, wartime propaganda or clever marketing. Over time, their origins became blurred, leaving familiar slogans that are often repeated with greater confidence than the evidence warrants.
Consider the humble apple.
An apple a day — but who said so?
Not the poisoned apple from Snow White, but the ordinary fruit that promises something almost as magical: keeping the doctor away.
The saying “An apple a day keeps the doctor away” sounds like a miniature medical recommendation. Yet no clinical trial established that one apple is the precise daily dose needed to prevent illness. There is no scientific formula for calculating the doctor-repelling properties of a Granny Smith.
The saying has older roots. A version documented in Wales in the 19th century went: “Eat an apple on going to bed, and you’ll keep the doctor from earning his bread.” The rhyme was memorable, and its message spread through generations.
The advice itself is not entirely misguided. Apples provide dietary fibre and beneficial plant compounds, and eating them can form part of a healthy diet. But that is not the same as proving that eating one apple every day will keep illness at bay or eliminate the need for medical care.
The distinction matters. A reasonable piece of dietary advice became a sweeping promise of good health, thanks largely to a catchy rhyme and generations of repetition.
The apple never needed a laboratory to become a health rule. It needed a memorable slogan.
But not every health myth began with a rhyme. Some acquired their authority through something far more deliberate: propaganda.
Carrots, wartime secrets and night vision
During World War II, British publicity helped popularise the idea that eating carrots could give people exceptional night vision.
The story was particularly useful at a time when Britain needed to protect information about its advances in airborne radar technology, which helped Royal Air Force crews locate enemy aircraft at night. Publicity surrounding carrots and the supposed superior eyesight of British pilots offered a convenient explanation for their effectiveness.
Carrots were also promoted as a useful food during wartime rationing.
The story had a scientific basis, but only up to a point. Carrots contain beta-carotene, which the body converts into vitamin A. This vitamin is essential for normal vision, particularly in low-light conditions. A deficiency can cause night blindness.
However, eating extra carrots will not give someone extraordinary night vision if that person already gets enough vitamin A.
The distinction between correcting a deficiency and improving an already healthy person’s eyesight is important. The first is supported by science; the second is not.
The wartime carrot story illustrates how a little scientific truth can lend credibility to a much bigger claim. Although the precise role of propaganda in creating the myth is debated, the association between carrots and exceptional night vision proved remarkably durable.
Sometimes, a myth survives because it contains just enough truth to sound convincing.
And sometimes, it does not need a wartime cover story at all. A clever marketing campaign can do the job.
Breakfast: the most important meal — or the best-selling one?
For generations, people have been told that breakfast is “the most important meal of the day”. Skipping it has often been portrayed as an unhealthy habit, particularly for children.
But how firmly is this familiar rule supported by nutritional science?
One part of the story involves John Harvey Kellogg, a physician who ran the Battle Creek Sanitarium in Michigan, and his brother, Will Keith Kellogg, who helped turn breakfast cereal into a commercial success. Their work contributed to the growth of the breakfast cereal industry and the promotion of cereal as a convenient, wholesome food.
As breakfast products became increasingly commercialised, advertising helped reinforce the idea that a proper morning meal was essential to starting the day well.
However, it would be too simplistic to attribute the entire breakfast-is-best message to cereal manufacturers. Breakfast has long been part of many cultures, and its importance has also been discussed in nutritional and public-health research.
What science does not establish is that breakfast must be the most important meal for every person, regardless of age, health, lifestyle or dietary needs. Research on breakfast and health is complex, and findings can vary according to the outcome being studied and the people involved.
For some people, breakfast is an important opportunity to obtain essential nutrients and maintain energy levels. Others may follow different eating patterns that suit their circumstances.
The lesson is not that breakfast is unnecessary or that cereal advertising is inherently misleading. It is that a universal nutritional rule deserves closer examination before it is accepted as scientific fact.
Perhaps the real marketing success was not simply selling breakfast cereal, but helping establish a particular idea of what a healthy morning should look like.
Marketing has also helped shape another familiar health target — one that now follows us around on our wrists.
Why 10,000 steps?
Today, fitness trackers turn walking into a daily countdown. Every step brings us closer to that familiar target of 10,000, and reaching it can feel like completing a health requirement.
But why 10,000? Why not 8,000 or 12,000?
The answer takes us to Japan in the 1960s, when a pedometer called Manpo-kei, roughly translated as “10,000-step meter”, was marketed as a way to encourage people to walk more. The round number made an appealing, memorable fitness goal.
The target was not originally established by research demonstrating that every person needed exactly 10,000 steps a day to remain healthy. Its popularity grew from a combination of a simple message, a marketable product and the appeal of a clear daily goal.
Subsequent research has found that walking regularly offers substantial health benefits, but those benefits do not begin only when a person reaches 10,000 steps. Studies suggest that lower daily step counts can also be associated with better health outcomes, with the relationship varying according to factors such as age and the outcome being measured.
For some people, 10,000 steps may be a useful and achievable target. For others, particularly those who are older or have mobility limitations, a lower goal may be more appropriate.
The important thing is to remain physically active in ways that suit one’s health and circumstances.
So, the next time your smartwatch congratulates you for reaching 10,000 steps, enjoy the achievement. Just remember that it is a popular fitness target, not a magical biological finish line.
When familiar advice meets scientific evidence
Apples are nutritious. Carrots provide nutrients essential for normal vision. Walking regularly benefits health. Breakfast can be a valuable part of a balanced diet.
None of these facts needs to be discarded simply because the familiar slogans surrounding them have been exaggerated or oversimplified.
The real question is how we distinguish sound advice from claims that have become accepted through repetition rather than evidence.
Health recommendations can originate in many places: scientific research, clinical experience, cultural traditions, commercial campaigns and even wartime information strategies. Some may eventually find support in scientific evidence; others may need to be revised as our understanding improves.
That is why science journalism matters. Journalists must look beyond familiar claims, trace their origins, examine the available evidence and explain what researchers know — as well as what remains uncertain.
A catchy slogan may help people remember a message, but memorability is not proof of scientific validity. Nor does the involvement of a scientist, university or health-related company automatically make a claim reliable.
Readers deserve more than repetition. They deserve context, evidence and an honest explanation of uncertainty.
Perhaps that is the real lesson behind the apple, the carrot, breakfast and the 10,000-step target: health advice does not become scientific simply because we have heard it a thousand times.
And like characters in a fairy tale, familiar health slogans can live happily ever after in the public imagination — even when the scientific evidence tells a more complicated story.
About the Author : Yves Ng Xin Yi is pursuing a bachelor’s degree in Biomedical Science at Universiti Kebangsaan Malaysia. The writer is participating in The Petri Dish Fellowship Writing Lab.
