Every year, millions of people follow advice based on myths they’ve heard since childhood-myths that sound plausible, come from trusted sources, or are repeated so often they feel like truth. In healthcare, these myths don’t just cause confusion-they can lead to poor decisions, delayed care, or even harm. The good news? Most of them have been thoroughly debunked by science. The challenge? They keep coming back.
Myth: You Need to Drink Eight Glasses of Water a Day
This one’s everywhere. From school textbooks to fitness apps, you’re told to drink eight glasses of water daily to stay healthy. But there’s no scientific basis for this number. Dr. Heinz Valtin, a kidney specialist at Dartmouth Medical School, reviewed over 100 peer-reviewed studies in 2002 and found zero evidence supporting the eight-glass rule. Your body doesn’t need a fixed amount-it needs enough to replace what you lose through sweat, urine, and breathing.
Water comes from more than just your bottle. Fruits, vegetables, soups, coffee, and tea all contribute. A healthy adult in a moderate climate typically gets enough hydration through food and drink without forcing themselves to count glasses. Overhydration can even be dangerous, especially for older adults or those with kidney issues. The real signal? Thirst. If you’re not thirsty and your urine is light yellow, you’re likely fine.
Myth: You Lose 70-80% of Your Body Heat Through Your Head
This myth started with a 1950s U.S. military study where subjects wore Arctic survival gear-except their heads were exposed. Naturally, they lost a lot of heat through their heads. But that’s because their heads were the only uncovered part. If you go outside in winter wearing only a swimsuit, you’ll lose heat equally from every exposed area.
Modern research shows the head makes up about 7-10% of your total body surface area. That means it loses roughly that same percentage of heat-not 70%. Covering your head helps, but so does covering your hands, neck, or feet. The idea that your head is a special heat-loss hotspot is misleading. It’s not that your head is extra leaky-it’s that people forget to cover it.
Myth: Chewing Gum Stays in Your Stomach for Seven Years
Parents have used this one to scare kids into spitting out gum since the 1950s. The truth? Your digestive system doesn’t break down gum the way it breaks down food, but it doesn’t get stuck either. The base of chewing gum is indigestible, yes-but your gut moves it along just like any other indigestible material, like corn husks or fiber.
According to Dr. Ian Tullberg, a family medicine specialist at UCHealth, gum passes through your system in two to four days. There’s no evidence of it sticking to your stomach lining or causing blockages in healthy people. The only real risk? Swallowing large amounts of gum repeatedly in a short time, especially in young children with smaller digestive tracts. But one piece? It’s gone before you forget you chewed it.
Myth: Sugar Makes Kids Hyperactive
It’s a classic scene: a child eats candy at a birthday party, then runs around like a maniac. Parents blame sugar. But over 23 double-blind, controlled studies-including a major 2021 meta-analysis in JAMA Pediatrics-have found no link between sugar intake and increased hyperactivity in children.
So why does it feel true? Because context matters. Parties are exciting. Kids are excited. Parents expect sugar to cause chaos, so they see it even when it’s not there. This is called confirmation bias. Worse, the sugar industry spent decades funding research and lobbying to keep this myth alive, as documented in Archives of Internal Medicine in 2016. The real issue? Processed foods high in sugar often replace nutrient-dense meals, leading to poor energy regulation-not hyperactivity.
Myth: We Only Use 10% of Our Brain
This myth has been repeated in movies, ads, and self-help books for nearly a century. The idea that we’re only tapping into a fraction of our brain’s potential sounds empowering-until you look at the science.
Neuroscientists have used fMRI and PET scans for decades. These tools show that every part of the brain has a function-even during sleep. There’s no dormant 90%. Damage to almost any area causes measurable deficits. If we only used 10%, brain injuries would be far less serious. The myth likely came from a misinterpretation of psychologist William James’ writings in the 1920s, which were about untapped potential, not brain anatomy.
What’s really happening? Your brain is always active. Some areas fire more during specific tasks, but even resting, your brain uses 20% of your body’s energy. You’re using 100%-just not all at once.
Myth: Superfoods Like Acai or Goji Berries Are Miracle Cures
“Superfood” isn’t a scientific term. It’s a marketing label. Goji berries, acai bowls, chia seeds, and kale are nutritious-but they’re not magic. The European Food Information Council reviewed decades of research and found no evidence that these foods offer unique health benefits beyond what a balanced diet provides.
Blueberries, spinach, and apples have similar antioxidant levels. A bowl of acai smoothie doesn’t reverse aging or burn fat. It’s just fruit with sugar and calories. The real problem? People buy expensive superfoods thinking they’re making a health breakthrough, while ignoring basics like eating vegetables, limiting processed foods, and staying active.
There’s no single food that can fix poor habits. Nutrition isn’t about finding the next miracle ingredient-it’s about consistency, variety, and balance.
Why Do These Myths Stick Around?
It’s not just ignorance. Myths survive because they’re simple, emotionally satisfying, or tied to identity. “Sugar makes kids hyper” lets parents blame the candy, not their own routines. “Eight glasses a day” gives people a clear, easy rule to follow. “We only use 10% of our brain” makes you feel like you’ve got untapped power.
Also, myths spread faster than facts. A 2022 MIT study found that misinformation on social media spreads six times faster than corrected information. Even when people see a myth debunked, they often remember the myth more clearly-especially if the correction is poorly framed.
This is called the familiarity backfire effect. Repeating the myth-even to refute it-can make it feel more true. That’s why experts now recommend the “truth sandwich”: state the fact, briefly mention the myth with clear labeling (e.g., “Some people believe…”), then restate the fact.
How to Spot and Fight Health Myths
Not every myth is dangerous, but when it comes to health, even small misunderstandings can add up. Here’s how to tell fact from fiction:
- Check the source. Is it a university, government health agency (like CDC or WHO), or peer-reviewed journal? Or is it a blog, influencer, or product ad?
- Look for evidence. Does it cite studies? Are those studies real and recent? A single anecdote isn’t proof.
- Ask: “Who benefits?” If a product claims to “cure” something with a miracle ingredient, it’s likely selling you something.
- Be wary of absolutes. “Always,” “never,” “everyone,” “the only way”-these are red flags. Biology is rarely that simple.
When in doubt, talk to your doctor or pharmacist. They’re trained to separate myths from medical facts-and they’ve heard them all before.
What’s Changing in Patient Education?
Healthcare institutions are finally catching on. In 2023, 68 U.S. hospitals added myth-busting sections to their patient education materials-up from just 12 in 2020. The American Hospital Association says patients who get myth corrections are 31% more likely to follow treatment plans.
Organizations like the WHO’s Myth Busters initiative have corrected over 2,300 myths in 187 countries. Google now shows “About This Result” boxes next to search results, pulling in fact-checks from trusted sources. And AI tools like MIT’s TruthGuard are being tested to predict new myths before they go viral.
The goal isn’t to shame people for believing myths. It’s to make accurate information easy to find, understand, and trust.
Final Thought: Knowledge Is a Habit, Not a One-Time Fix
Debunking a myth once doesn’t erase it from someone’s mind. Research shows it takes 3 to 5 exposures to the correct information, in different contexts, before a belief truly shifts. That’s why patient education needs to be ongoing-not just a pamphlet at the clinic.
Ask questions. Double-check claims. Share corrections kindly. The most powerful tool against myths isn’t a fancy app or a viral video-it’s a curious, skeptical, and informed mindset.
Is it true that you need to drink eight glasses of water every day?
No, there’s no scientific evidence supporting the eight-glass rule. Hydration needs vary by person, activity level, climate, and diet. Water comes from food and other drinks too. Thirst and light yellow urine are better indicators than counting glasses.
Does chewing gum stay in your stomach for seven years?
No. While your body can’t digest the gum base, it passes through your digestive system in two to four days, just like other indigestible materials. It doesn’t stick to your stomach or intestines unless swallowed in very large amounts over time.
Can sugar cause hyperactivity in children?
No. More than 20 controlled studies, including a 2021 meta-analysis in JAMA Pediatrics, found no link between sugar intake and hyperactivity. The belief persists due to cultural expectations and confirmation bias-not science.
Do we only use 10% of our brain?
No. Modern brain imaging shows all parts of the brain are active at different times. Even during rest, your brain uses significant energy. The 10% myth is a misunderstanding from outdated psychology and has been thoroughly disproven by neuroscience.
Are superfoods like acai or goji berries better than regular fruits and vegetables?
No. “Superfood” is a marketing term, not a scientific one. Acai and goji berries are nutritious, but they don’t offer unique benefits that can’t be found in common foods like blueberries, spinach, or apples. A balanced diet is more effective than any single “miracle” food.
Why do health myths spread so easily?
Myths stick because they’re simple, emotionally satisfying, or confirm what people already believe. They spread faster than facts online, especially when tied to identity, culture, or profit. Even debunking can backfire if done poorly-repeating the myth without clear labeling can reinforce it.
How can I tell if a health claim is true?
Check the source: Is it a university, government agency, or peer-reviewed journal? Look for citations, not anecdotes. Be skeptical of absolute claims (“always,” “never,” “miracle cure”). If a product is being sold, ask: Who benefits? When in doubt, talk to a healthcare professional.
