“Should you brush your teeth before or after meals?”, “Do you wash your hands before using the restroom, or after?”, “Does skipping breakfast actually help you concentrate?”. These questions are not unique to one school or one country. Teenagers in South Korea, Japan, the United States, Europe, and Southeast Asia ask the same things on online forums and social media. The confusion does not come from a lack of interest, but from the fact that different countries teach different ‘correct’ answers and those answers collide online.
In South Korea and Japan, public health campaigns have long emphasized brushing immediately after meals. Posters in school health offices often repeat the message: brush right after eating. In contrast, many dental guidelines in the United States and the United Kingdom advise waiting 20 to 30 minutes after consuming acidic foods or drinks. Brushing too soon in an acidic environment can temporarily weaken tooth enamel.
Yet across countries, one pattern remains consistent: actual teen behavior. Observations and surveys show that many adolescents brush for less than a minute—often around 40 seconds. The debate over when to brush often overshadows the more pressing issue of how and how long teens actually brush.
In many countries, including South Korea, handwashing education focuses almost entirely on washing hands after using the restroom. In contrast, countries such as the United States and Germany also emphasize washing hands before entering the restroom, since hands already carry bacteria from phones, desks, and door handles.
This difference reflects not hygiene standards, but what kind of risk each culture emphasizes: personal cleanliness versus preventing the spread of contamination. As a result, teenagers often grow up believing that the method they learned is the only correct one.
In South Korea and Japan, skipping breakfast is common due to early school start times and long commutes. In some Western countries, breakfast is treated as part of academic preparation, with schools even providing morning meals.
Within this contrast, the idea that “skipping breakfast makes your mind clearer” spreads easily online.
Research, however, paints a more complex picture. Regular meals help stabilize energy levels and mood, and recent studies suggest that eating patterns are linked to the gut microbiome, which can influence fatigue and cognitive performance. Short-term sensations of alertness do not always reflect long-term effects on the body.
In tropical regions, multiple showers a day are common due to heat and humidity. In parts of Europe, nighttime showers are often part of a sleep routine. In South Korea, morning showers are associated with alertness, while evening showers are linked to stress relief.
These routines are shaped less by personal preference and more by climate, commute times, and late-night study culture. Many health habits that appear to be individual choices are, in reality, responses to environmental conditions.
In the United States and Europe, there is growing debate over restricting energy drink sales to adolescents. The concern is not caffeine alone, but high sugar content and consumption patterns.
Across countries, a similar behavior appears during exam periods: teenagers consume energy drinks late at night to stay awake. Over time, this habit disrupts sleep cycles and places stress on oral and overall health. The risk lies not in a single ingredient, but in repeated behavior.
Advice on post-exercise nutrition varies by country, but experts generally agree that context matters. The type and intensity of exercise, along with individual needs, all play a role.
For teenagers, school schedules, cafeteria hours, and access to food often dictate what is realistically possible. Once again, health behavior is shaped less by motivation than by structure.
Many of the health “rules” we accept as common sense are not the result of ignorance, but of education systems, cultural norms, and daily living conditions. Digital media brings these different standards together, leaving teenagers to navigate conflicting advice.
Reexamining small health myths is not simply about correcting facts. It is about understanding how young people around the world make choices within the environments they are given—and recognizing health as a shared, structural issue rather than a purely individual responsibility.
By. Chanhyuk Lee