10 Health Lies You've Been Told Your Whole Life

A wise person once said, "Don't believe everything you hear" — and that's especially true when it comes to questionable health information you hear on the internet and social media. (Appropriately, that popular saying is likely a distortion of an often misattributed phrase written by Edgar Allen Poe, "Believe nothing you hear, and only one half that you see.”)

While a lot of health advice started with the best of intentions,  much of it also originated when medicine wasn't advanced as it is today or in some cases the advice was misinterpreted or distorted over the years. Some of these health myths have lingered long enough to become widely believed. Here are 10 health myths you've been told your entire life and why they're untrue.

It happens to the best of us. You're craving pizza, and then the universe decides to mess with you, so in a fit of clumsiness, you drop it. Naturally, you think, "If I pick it up before I count to five, the pesky bacteria won't have a chance." How fast can bacteria be, anyway?

Sorry to burst your bubble, but according to science, it's faster than five seconds. Researchers at Rutgers University in Newark decided to test the theory that it takes bacteria five seconds to reach dropped food. They dropped various items onto bacteria-covered surfaces to see how quickly germs would latch onto the food. The result? Disappointingly to many, bacteria transferred to the food instantly — in a split second. 

The researchers also discovered that different foods attract bacteria at different rates. For example, watermelon instantly picked up 97% of floor bacteria, making it as risky to eat after a split second as after 5 minutes, while bread initially absorbed only 0.1% but reached 10% contamination after 5 seconds. So next time you get clumsy and drop that French fry, better not risk it.

Related: How Long You Have To Safely Eat Unrefrigerated Foods

An age-old zombie movie trope of Gandalf-bearded skeletons with long fingernails was promoted as a scientifically backed fact. But, to the great disappointment of fans of the macabre, our hair and fingernails stop growing as soon as we are no more. Skin cells die within 24 hours of death because there's no oxygen from a living heartbeat to keep them alive. Your body also stops producing the necessary proteins for hair and nail growth. 

The illusion of post-mortem hairstyles and manicures comes from a biological phenomenon. As your body dehydrates after death, the skin shrinks. This shrinkage makes hair and nails appear longer, even though they haven't grown a single bit.

You've definitely heard the fear-mongering health myth that if you're not drinking eight glasses of water daily, you're probably human garbage, walking around dehydrated and likely to die of thirst. Well, not exactly. Aaron E. Carroll, co-author of a 2007 paper published in the BMJ on medical myths and the book "Don't Swallow Your Gum!: Myths, Half-Truths, and Outright Lies About Your Body and Health," writes in the New York Times that this so-called medical advice is based on no scientific facts whatsoever, but rather a misreading of a recommendation.

In 1945, the Food and Nutrition Board issued a report saying that people need about 2.5 liters, equal to eight glasses of water per day. But the report also states that 'Most of this quantity is contained in prepared foods.'

So, while hydration is essential to keep you healthy and vital, you don't have to count glasses throughout the day. Water can be consumed from other sources — fruits, vegetables, tea, coffee, and even beer contain water.

Related: Fitness Myths That Could Be Sabotaging Your Workouts

Let's say you swallowed a piece of gum in 1984, the year Ronald Reagan was re-elected as President. According to the myth, that gum would still be in your stomach until 1991, the second year of George H. W. Bush's term.

When we were kids, the worst thing that could happen was swallowing gum, because it would supposedly stay there for seven years. Fortunately, this is just a myth, and swallowed gum doesn't set up camp in your stomach.

Chewing gum, along with flavoring, sweeteners, and preservatives, is made of a gum base. Traditionally, this base was made from the sap of the Sapodilla tree. However, by the mid-20th century, it was increasingly replaced by FDA-approved natural or synthetic polymers, including butyl rubber. This ingredient is resistant to stomach acid and digestive enzymes in the intestines, which probably started the myth.

The fact that it cannot be broken down doesn't mean it just stays in your stomach rent-free. Since it is small enough, it will eventually find its way down the digestive tract. So, don't worry, an accidentally swollen gum will not make you part Wrigley. 

Related: 15 Things We've All Eaten That No One Wants to Admit

When you do or say something downright stupid, you can also rely on the comforting thought that you use only a limited portion of your intelligence, 10% to be precise. But although, comforting, this is a century-old myth that is nothing but an ignorant middle finger to advance neuroscience.

Extensive studies and research debunk this myth, and a number of brain imaging and microstructural analyses show that virtually every part of the brain has some activity, even when we’re resting or asleep. A simple effort like clenching and unclenching your hand requires activity in more than a tenth of the brain.

Also, if we used only 10% of our brains, damage to the other 90% wouldn’t impair us. In reality, even small amounts of brain damage can have profound effects on cognition, emotion, and motor functions.

Carrots can improve your eyesight, just as eating spinach can turn you into a cartoon jacked-up sailor. 

Carrots are very nutritious and packed with vitamins beneficial for your well-being. They contain Vitamin A in the form of beta carotene, which is good for eye health, but the idea that eating them can improve impaired eyesight is another scientifically unsupported myth that started as war propaganda.

During WWII, to mask the development of radar technology that helped the Royal Air Force (RAF) successfully combat German bombers, the Air Ministry issued press releases stating that British pilots were eating an excess of carrots to give them exceptional night vision. What started as a ruse turned into pseudo-medical advice, giving false hope to people with poor eyesight that eating a carrot could help them see better.

When it's cold outside, we make sure to put on a cozy hat because we've been told that most of our body heat escapes through our heads. But then why bother with pants and a jacket, you might wonder? Because this is nothing but a fable likely originating from outdated survival manuals or misinterpreted military experiments. For example, a U.S. Army survival manual from 1970 recommends covering the head when it is cold since '40 to 45 percent of body heat' is lost from the head.

The truth is, you can lose heat from any exposed part of your body, not just your noggin. If you go out in the cold without a hat, sure, you'll lose heat through your head—but that's because it's uncovered, not because it's a special heat-loss hotspot. The amount of heat you lose from any body part depends on its surface area and how well it's insulated.

The idea that sugar turns kids into bouncing balls of energy has been around for ages. However, plenty of studies consistently show no direct link between sugar consumption and hyperactivity. 

This myth probably sticks around because of confirmation bias — parents notice their kids’ excitement at parties (where sugary treats are abundant) and blame the sugar, ignoring other factors like the general party excitement.

In reality, if your kid is acting unhinged and all over the place it’s more likely the overall environment than a sugary snack. You should continue limiting the sugar consumption in your kid, but for health reasons that are beyond hyper enegery.

"'You'll catch your death in that cold" is something we've been hearing forever during the colder months. While it's common to associate murky weather with sniffing and coughing, research shows that cold weather doesn't make you sick — viruses do. Prolonged exposure to cold temperatures can weaken your immune system, making you more susceptible to the bacteria and viruses that cause illness.

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No, it's not smart to drink your pee, no matter how many times you've seen it in movies. Urine is not sterile. While it is generally free from harmful bacteria when urine leaves the kidneys, research shows it can pick up bacteria from the urinary tract and urethra on its way out. Even in healthy individuals, urine contains a diverse community of bacteria.

This myth might have started because, in certain medical contexts, fresh urine can be relatively clean compared to other bodily fluids. However, it's not completely sterile. So, let's flush this myth before you consider urine as a disinfectant."