Personal Health

Health Is Not About How Much You Weigh: 10 Popular Health Myths You Probably Believe, Debunked

You'll be surprised to learn what's good for you and what's not.

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Old medical wives’ tales never die. We hear them all the time. “Feed a cold, starve a fever” (uh, uh, light, balanced nutrition for both, please). “Chocolate causes acne” (nope, bacteria cause acne). Here are 10 more medical myths that need to be put to rest.

1. Avoid dairy when you have a cold

A long-time perceived “truth” is that dairy products like milk and cheese are to be avoided when you have a cold because they increase the mucous your body is already over-producing. Add this to the long list of medical myths that are just that, myths. The truth is there has not been any scientific connection found between milk products and runny noses.

Jennifer Collins, an assistant professor and a doctor specializing in allergy, asthma and immunology at the New York Eye and Ear Infirmary says, "I have patients who swear that milk makes them produce more mucous." Despite this, Collins has never been able to find a single piece of credible research supporting this perception. Indeed, a study in Australia of 60 cold sufferers found no relationship between drinking milk and increased production of mucous. 

2. Vaccines cause autism

The mother of all medical whoppers. Can we put this dangerous and erroneous claim to bed once and for all? The study that got this myth rolling has been unequivocally shown to be flawed. Vaccines do not cause autism, or any other developmental disorder.  They do prevent potentially serious illnesses like polio, measles, mumps, and whooping cough. People buying into this anti-vax myth, by avoiding vaccines for their children or themselves, are contributing to the comeback of diseases once thought conquered.

3. Cold weather causes colds

Many kids have heard it: “Bundle up! It’s freezing outside!  You’ll catch your death of cold!” Actually, mom or dad, no. Cold weather does not cause colds. Cold viruses cause colds. The truth is that you are more likely to catch a cold indoors than outdoors. When it is chilly outside, people stay indoors, in closer proximity to other people. The heat is on, drying up your mucous membrane, the lining in your respiratory system that helps protect you from viruses and germs. 

Your dry mucous membrane makes you more susceptible to the virus your co-worker just inadvertently left on the doorknob to the conference room. You turn the knob to get into the room, unconsciously touch your face, and boom. You are about to have a runny nose. It wasn’t the cold weather outside that gave you that runny nose, it was the doorknob virus. 

So go on outside, dress for your own comfort. In fact, take a long walk in the cold weather, because exercise helps strengthen your immune system, which will help protect you from those sneaky doorknobs. (Don’t forget to wash your hands a lot and keep your hands away from your eyes and nose, which are the most common entry points for the cold virus.)

4. Shaving makes your hair grow back thicker and darker

Debunking this one is going to make your teenage son, who is trying to grow that hipster goatee, frustrated. Nope, shaving does not make your hair grow back any thicker or darker or faster. As far back as 1928, tests were conducted on shavers that zapped this myth, yet still it persists. When you shave, the hair grows back with a blunt edge which, as it wears down, may give the appearance of being thicker. Also, because the new hair has not been bleached by the sun, it may at first seem darker. But it isn’t thicker or darker (at least not for long) than the hair it replaced. So Junior can stop shaving so much. His whiskers will get there with time, not razor burn.

5. You need to drink 8 glasses of water a day

Want to stop visiting the bathroom so often? Stop buying into the myththat you should shrink eight glasses of water a day. According to Rachel Vreeman in the British Medical Journal, “There is no evidence to suggest that you need that much water.”  This medical myth may have evolved from a 1945 recommendation from the Food and Nutrition Board of the National Research Council, which recommended approximately “1 milliliter of water for each calorie of food,” which would amount to roughly 2 to 2.5 quarts per day (64 to 80 ounces). However, often overlooked is that the recommendation said fluids could be obtained from many sources, including juice, coffee, tea, fruits, vegetables, etc.

So cut down on the water. Maybe sub in a couple apples and a carrot or two. That way you will get the fluids you want, some nutrition to boot, and save yourself trips to the bathroom, including ones in the middle of the night that can deprive you of sleep.

6. Humans only use 10 percent of our brains

It’s very admirable to want to improve yourself, and be the best you can be, but do not fall for this popular claim. It’s just not true. The notion that 90 percent of our brains go unused grew out of early-20th-century snake oil salesmen who were trying to sell potions that supposedly made you smarter. Amazing how lies gain a life of their own. Countless MRIs, CT scans and imaging scans have been done of the brain, and found that there are no parts of our brain that are slacking off. Our brains, just like the rest of the organs of our body, are always firing. Even studies of individual brain cells reveal no inactivity. They are all busy little brain beavers.

7. Reading in the dark will damage your eyes

We never want to discourage our kids from reading, even under the blanket after lights-out. So don’t be worried about Sally’s eyes in that dim under-the-cover light, because it is a myth that reading in low light damages your eyesight. This myth probably came from the fact that you can get eyestrain from low-light reading, which can affect the clarity of your vision temporarily. However, a night’s rest and your eyes are as good as new. There is no evidence that any permanent damage can be done by this practice. Read away, young Sally. 

8. Eating turkey makes you sleepy

How many of us, after that big Thanksgiving dinner, have slowly plodded to the bedroom, loosened the pants, and taken a nice long nap? Don’t raise your hand. There are too many of you to count. From this has come the myth that eating turkey makes you drowsy. 

Researchers for years were convinced that this was true, and they pointed to an amino acid in turkey called tryptophan, which is a chemical known to make you sleepy. Trouble is, further research showed that turkey doesn’t have any more tryptophan than chicken or any other poultry. The likely cause of your drowsiness is the wine or beer you had with your turkey dinner, or maybe the spike in blood sugar after that second piece of pecan pie. Don’t make the poor turkey take the blame; it already made the ultimate sacrifice.

9. If you are overweight, you are unhealthy

Looks can deceive and there is a lot of concern about obesity these days.  he truth of the matter is that the key to health is not your weight, it's your fitness level. Even if you are overweight, if you exercise regularly, as was shown in a study of over 25,000 men over 23 years, published in the journal Applied Physiology, Nutrition and Metabolism, your chance of dying is half that of a “normal” size out-of-shape man. That normal guy is at a much higher risk of death than from having type 2 diabetes, high blood pressure, or even smoking. This is not to say that being overweight is a good thing, as other complications can come from it, but staying physically active can stave off health problems even if you are overweight.

10. Wait 30 minutes after eating before swimming

You just finished your lakeside picnic lunch and now the kids want to jump into the water. No, you say: you have to wait 30 minutes after eating before swimming. You don’t want to get cramps and drown, do you? Sorry, you’re perpetuating a myth. This untruth grew from the idea that the stomach needs energy to digest food, and therefore the body diverts blood from the muscles to the core to aid in the process. The lack of blood to the muscles causes muscle cramps and increases risk of drowning. 

Problem is, while this process does happen to a small degree, the amount of blood diverted isn’t enough to cause cramping. There’s plenty of blood to go around. No one is saying you should eat a huge meal and then start swimming laps, but don’t sweat in the hot sun. Dive on in with the kids. The water’s fine.

Larry Schwartz is a Brooklyn-based freelance writer with a focus on health, science and American history.