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We only use 10% of our brains

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The origins of this myth are unclear but neuroscientists are adamant that the majority of the human brain is in use for the majority of the time. Functional magnetic resonance imaging (fMRI) shows that this is true even when we are asleep or when we’re performing only very simple actions.

A heart attack is always accompanied by chest pain

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This is a particularly dangerous myth. While many heart attacks are accompanied by pain, others are not. Some heart attack victims describe pain in the neck, back or left arm, or tightness or squeezing in the chest, while others don’t even report this. Sweating, vomiting, and even an overwhelming feeling of doom are other common symptoms.

A defibrillator can restart a flatlining heart

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Whatever ER and other TV shows might have you believe, a flatlining heart cannot be restarted. If it’s flatlining, there’s no electrical activity and, just as you can’t jumpstart a car with a dead battery, you can’t use a defibrillator to restart a flatlined heart. CPR, followed by a high dose of adrenalin, is the only thing that might help.

Carrots improve night vision

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Carrots are rich in vitamin A, which is crucial for eye health and good vision. However, eating more carrots will not help you see better: this is a myth that dates to wartime Britain when government propaganda popularized the belief that it was a carrot-rich diet that allowed the RAF to locate Luftwaffe bombers rather than new radar technology.

The appendix has no function

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Frequently removed without much thought during abdominal operations for other reasons, recent scientific advances suggest that the appendix performs several valuable functions in the human body. It’s a reservoir for “good” bacteria that facilitate healthy digestion and is also thought to play an important role in the body’s immune function.

Tilt your head back to stop a nosebleed

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If you tilt your head back when you have a nosebleed, the blood will run down the back of your throat. You’re then likely to swallow it – and swallowed blood can irritate the stomach lining and induce vomiting. Instead, sit down, tilt your head forward and pinch the soft part of your nose together for at least ten minutes.

Large feet equate to larger private parts

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In a myth-busting that will please as many men as it disappoints others, there is no scientific statistically significant correlation between feet size and genitalia size. It seems likely that this is a myth created by a man with large feet. However, it’s worth noting that, when erect, shorter penises increase in length by almost twice as much as longer ones.

Feed a cold but starve a fever

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Whether you have a cold or a fever (or both!), your body needs sufficient nutrition – and fluids – in order to fight it off successfully. The origin of the myth may stem from the fact that fevers often suppress the appetite, making it harder to take in the necessary nutrients. Small, frequent meals may be easier to eat than larger ones.

Antibiotics can cure a cold

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The clue is in the name. Antibiotics work against bacteria by destroying their cell membranes and disrupting their replication. Colds are caused by viruses and, as viruses don’t have cell membranes, antibiotics are ineffective. Worse, giving unnecessary antibiotics is known to kill “good” bacteria that live naturally in the guts.

Eggs are bad for your cholesterol levels

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A single large egg contains around 186 mg of cholesterol – and all of this is found in the yolk. If you have normal blood cholesterol levels, eggs are very unlikely to affect this. And even if you have raised cholesterol, eating eggs might still be acceptable if your diet is otherwise low in the substance.

You’ll catch a cold if you go out in the rain

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Have you ever been warned that you’ll catch a cold if you go out in the rain? Although a cold is caused by a virus, which you can’t catch from the rain, there’s some truth behind this myth. Staying cold and damp for long periods of time can lower body temperature enough to affect the immune system and make you more susceptible to contracting a virus.

Sugar makes children hyperactive

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The myth that sugar makes children hyperactive stems from a single research study back in the 1970s. Since then, not a single other study has backed up the findings. On the other hand, sugar does cause rapid blood sugar spikes and subsequent equally dramatic crashes, which can make a child hungry and grumpy.

Flu shots give you flu

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Flu shots do not give you flu. There, we said it! The virus in the vaccination is inactivated, which means it cannot replicate in your body’s cells and, therefore, cannot give you flu. You may, experience a few hours of flu-like symptoms, including nausea and muscle aches. This is normal and is a sign that your body is learning to recognize the virus and prepare its immune response.

Men are more likely to have a heart attack than women

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Prior to menopause, the average woman has a lower risk of suffering a heart attack than the average man. After menopause, however, a woman’s risk profile increases to match a man’s. Unfortunately, many women do not experience the classic symptom of a heart attack – crushing chest pain – which means their heart attacks are more likely to be missed, sometimes with fatal consequences.

Yoga is always good for pain

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Despite the excellent PR, yoga isn’t always the solution for chronic pain. Whether or not it helps will depend on what’s causing the pain. In some cases, especially those involving joint problems, back pain or anything that stems from an injury, yoga may make matters worse. Consequently, it’s always sensible to seek medical advice beforehand.

Coffee helps you sober up

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Whatever your friends tell you, coffee won’t sober you up. No food or drink can do that. Instead, the only remedy is time – because that’s what’s needed to ensure the alcohol leaves your bloodstream. As a general rule of thumb, the body metabolises alcohol at a rate of about one unit per hour. However age, size and sex can all affect metabolism rates.

If you’re not sweating, you haven’t had a good workout

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Despite what you might think when you look around a gym, you can’t gauge the effectiveness of a work-out from how much someone is sweating. Some people naturally sweat much more than others. Other factors are also relevant: what someone is wearing, what the outside temperature or room ventilation is like, and so on.

You can stop a course of antibiotics once you feel better

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The only reason for stopping a course of antibiotics before you’ve finished it is if your doctor tells you to. Stopping a course too early risks a relapse of your illness and also contributes to the rise of antibiotic-resistant bacteria, which is a serious growing global problem.

Bright white teeth are healthy teeth

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Most people’s teeth are not pearly white. Indeed, they may not even be white at all. It’s quite common for healthy teeth to have a naturally yellowish hue. People who seek to change this via the use of bleaching products risk damaging their teeth, unless they do so under the supervision of a dentist.

You lose most body heat through your head

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Although you probably do feel warmer when you put on a hat, people actually lose heat proportionately across the surface of their skin. Children, whose head is larger in proportion to their body, do lose more heat through their head than an adult but even they will lose the majority of heat from elsewhere.

Vomiting means you have the flu

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Many people confuse influenza with “stomach flu”. True influenza rarely causes vomiting whereas it’s a major symptom of “stomach flu”. In reality, there’s no single illness called “stomach flu”; instead, people are referring to a gastrointestinal infection such as norovirus, rotavirus, Salmonella, or E. coli.

Broken hearts can’t kill you

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If you’ve ever shaken your head at the idea of the heroine in a Victorian novel dying of a broken heart, you shouldn’t be so cynical. Medical science has found proven links between mental health and heart attacks. For instance, the risk of suffering a heart attack following a traumatic event such as a bereavement is around double that of the risk in someone who isn’t grieving.

Thinner people are healthier people

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Have you ever heard of a “fat thin person”? Although someone may be visibly skinny, they can still have unhealthily high levels of fat deposits around their internal organs. They may also have high cholesterol, and both of these are risk factors for heart disease. Although it’s generally better to be thinner rather than fatter, good health means more than a measure of thinness.

Keep someone with concussion awake to keep them safe

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When dealing with someone with a concussion, medical advice is usually to keep them awake for the first five or six hours. This is to monitor them for potential signs of bleeding on the brain. After this period of time, however, sleep is best and, indeed, necessary for recovery. Keeping them awake can hinder this process.

Migraines are just bad headaches

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If you believe your migraine is “just” a headache, you could be denying yourself the help you need to avert future migraine attacks or deal with them more effectively. The causes of migraine are totally different from those of a headache, and the symptoms are more wide-ranging and potentially longer-lasting.

Rub frostbite to warm up

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If you’re unlucky enough to succumb to frostbite, your best chance of saving fingers, thumbs or the tip of your nose is knowing what to do – and what not to do. A natural response to extreme cold is to rub the affected area but, with frostbite, this will increase the damage to the affected skin.

Snoring is normal

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Snoring might be common but it definitely isn’t normal. Often a sign of sleep apnea, which is a form of temporarily obstructed breathing. It’s also a known risk factor for heart disease and potentially also for Alzheimer’s disease. As a result, it’s important to seek treatment if you’re a snorer – or married to one.

Heart attack risk comes down to “good” vs “bad” cholesterol levels

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It’s easy to dismiss your potential heart attack risk on the basis of “good” cholesterol levels. However, just as raised levels of “bad” cholesterol don’t automatically mean you’re heading for the cardiac ward, “good” cholesterol isn’t some sort of saviour. Heart attack risk is much more complex and includes many other factors including weight, activity and smoking.

Turkey helps you fall asleep

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Ever fallen asleep after your Thanksgiving dinner? Perhaps you told your family that it was turkey, rather than their company, that sent you to sleep. Unfortunately, although turkey meat contains an amino acid called tryptophan that can induce sleep, you’d have to eat five and a half pounds of turkey to feel the effects…

Running on a treadmill is better for your knees than the sidewalk

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Runner’s knee is a common complaint. However, whatever you’ve been told, switching to the treadmill instead of pounding the sidewalks won’t necessary alleviate the problem. Even though the treadmill’s surface is softer than the sidewalk, the main stress on your knees comes from the weight of your own body.

Eating less helps you lose weight

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Eating less seems to make good sense if you’re trying to lose weight. However, what you’re eating is at least as important as how much you’re eating. For instance, eating a diet rich in fiber, lean proteins and vegetables can enable you to eat a greater volume of food than the same number of calories consumed as fatty cuts of meat and donuts.

A six-pack means you’re in good shape

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A visible six-pack isn’t necessarily a sign of good health – especially if you’re female. For the abs to be visible, body fat has to be very low – and, in some cases, this will mean being too low to be healthy. In women, very low body fat can result in amenorrhea – when periods stop – and, in the longer-term, raise the risk of osteoporosis.

If there’s no pain, there’s no gain

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Contrary to the popular mantra, if you feel pain when you exercise, it’s a sign you should slow down or even stop what you’re doing. Inadvertent injury is easy during exercise and you can reduce your chance of suffering by listening to what your body is telling you. Continuing to exercise once you’re injured risks making that injury worse.

Detoxing is essential to cleanse your body

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If you believe Hollywood, detoxing is an essential part of the route to A-list stardom and an A-list body. However, whether you follow a detox diet, a juice diet or a cleansing diet, you’re kidding yourself. Your body is perfectly able to remove toxins all by itself, thanks to the work of the lungs, kidneys, and liver.

Humans shouldn’t eat dairy

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Although a significant proportion of adults are lactose intolerant, that doesn’t mean that dairy is automatically unsuitable for everyone. Eliminating dairy from the diet without replacing it with a suitable alternative risks long-term bone health. What’s more, even people who are lactose intolerant may find they can tolerate some forms of dairy, such as yoghurt.

Sleepwalkers shouldn’t be woken

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You’ve probably heard it said that sleepwalkers shouldn’t be wakened… but have you ever wondered why? In fact, there’s no real evidence to suggest that waking them is harmful. Quite the reverse: not waking a sleepwalker risks them getting into dangerous situations, such as driving a car while still asleep.

Some people need only a few hours sleep

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British Prime Minister Margaret Thatcher, also known as the ‘Iron Lady’, famously only survived on four hours of sleep per night. Although a very few people apparently benefit from a gene that genuinely allows them to thrive on four to six hours’ sleep, most people who claim to cope on such little shut-eye perform sub-optimally, regardless of how they feel.

Alcohol helps warm you up

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Your body’s natural response to the cold is to divert blood away from your skin and extremities to ensure that your brain and other vital organs stay warm. Alcohol does the opposite of this, which is someone who is inebriated is at greater risk of hypothermia than a sober person.

If you don’t have a bull’s eye mark, you don’t have Lyme’s Disease

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Although the bull’s eye rash is a classic sign of Lyme disease, it doesn’t appear in everyone who contracts the disease via the bite of an infected tick. Relying on the appearance of the rash before seeking treatment can result in long-term damage. You should also watch out for other common symptoms such as swollen lymph nodes and a fever.

You should pee on a jellyfish sting

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Yes, Chandler did it to Monica on Friends but, actually, Joey was wrong: peeing on a jellyfish sting isn’t a good idea. According to the American Red Cross, the urine can aggravate the stingers into releasing more venom. Instead, soak the affected area in warm water for 20 minutes or apply a hot pack wrapped in a towel.