2019 Medical Myths Busted

IU Day. All IU. All Day. Medical Myths—Busted! Dr. Aaron E. Carroll, MD, MS, IU Professor and "New York Times" blogger sits at a desk in front of a large window overlooking the Indianapolis skyline.

>> Another doctor named Rachel Vreeman and I wrote a paper a number of years ago now on medical myths that got way more publicity than we thought it would and we actually wound up writing a book and then 2 more after that on medical myths.

But a lot of what we try to focus on is beliefs that people are sure are true and they've been told by people they trust and often even understand why they think they are true but they're not and good research often proves that they're wrong.

Myth number 1. Drink 8 Glasses of Water a Day. Video footage of people drinking water.

The idea that we have to drink 8 glasses of water a day is I mean people just know it to be true, they just believe it.

They're told it by people they trust, they're told it by teachers, they're told it by nutritionists, they're told it by experts and even doctors and they're just no science behind that at all.

Most people think that the idea came from a nutrition counselor recommendation in the fifties, where a group of scientists got together and said "We think most people should have about 64 ounces or so of hydration a day" even though they really were just making that number up.

1950s black-and-white video footage of a man in a doctor's office drinking a glass of water as the doctor observes.

But what people don't remember is that there was sort of like a comma after that and it said "but you're going to get that in a normal diet" and most people on a good diet are going to get plenty of hydration.

Photos of fruits and vegetables.

This idea that you need 8 glasses of pure water a day is completely made up and there's no science or research behind it at all.

Myth number 2. Giving Sugar to Kids Makes Them Hyper.

First of all, I'm a pediatrician; I'm not going to advocate that we start giving kids sugar before bedtime.

But there's certainly a huge myth in the idea that sugar makes kids hyperactive or that sugar makes kids hyper.

And that is a myth in the sense that it's absolutely untrue.

There have been more randomized control trials or incredibly designed good trials to prove that sugar doesn't cause hyperactivity than probably almost any drug you've ever taken.

There's a review in the New England Journal of Medicine, I think they found at least 12 well-designed RCTs that looked at regular kids that looked at healthy kids that looked at kids with attention deficit hyperactivity disorder that looked at kids whose parents specifically said "My kid is hyper when he gets sugar." And the well-designed studies again and again and again show that sugar doesn't make kids hyper.

Myth number 3. Shaved Hair Grows Back Thicker and Darker. Video footage of a man shaving his face.

There's another myth that when you shave hair, it's going to grow back thicker, darker, or coarser than it did before.

This seems to apply more to women than to men who worry that if they shave hair where they don't want it, that somehow it's going to be worse than it was if they had left it alone.

This too is a myth.

When you do shave hair, when it first grows back and exits the skin, it can appear darker than it did before because it hasn't yet had time to be bleached by the sun.

When it first comes out, it might be thicker or feel coarser than it did before because it hasn't yet had time to rub against clothing and other things which will make it finer and which will make it less coarse.

But when it is done growing, it will be exactly the same as the hair that did before.

There again have been randomized controlled trials to prove this.

Myth number 4. Reading in the Dark Harms Eyesight. Photo of two young boys reading by the light of a small lamp.

There's widespread belief that reading in the dark or reading at night will hurt your eyes as if somehow you know that somehow could possibly be true.

So it is true that reading in the dark is harder than reading in light.

And when you work harder and any muscle works harder, after a while it starts to get tired and it starts to feel strain then it might actually hurt a little bit.

And when that happens, you should stop and then your muscles will be fine again.

But in the same way that when you run your legs might get tired and sometimes even hurt, doesn't mean you should never run again, it just means rest for a period of time and then you're going to be fine.

The same is true of eyesight.

Myth number 5. Eating Turkey Makes You Sleepy. A scene from the movie "A Christmas Story." A woman removes a turkey from the oven and sets it on a table. A man hovers over her.

>> Now it is well known throughout the Midwest that the old man is a turkey junkie.

>> The idea that turkey causes you to be sleepy is a complete myth and this is so engrained in our culture that everybody's even sure they know why turkey makes you sleepy, it's tryptophan, everybody just knows that.

And it is true that tryptophan is marketed as a sleep aid and tryptophan can make you sleepy but there's a few reasons why it has nothing to do with turkey.

The first is that turkey doesn't really have a lot of tryptophan in it.

It has no more tryptophan in it than chicken or ground beef.

It has significantly less tryptophan than pork products and cheese but nobody ever says a ham and cheese sandwich makes you sleepy, it's always turkey.

The second is if you buy tryptophan and you look on the box it will say on the side "Do not take this with food" because it's terribly absorbed with food, it needs to be taken on an empty stomach.

So the worst way to get the sleep-inducing effects of tryptophan would be to get it in a big meal like a Thanksgiving feast.

Several people sit around a long table as a woman carves a turkey.

There's nothing about this that's true.

There's lots of reasons why you might be sleepy on Thanksgiving.

Big meals in general can sometimes tend to make you sleepy.

Drinking alcohol can make you sleepy [inaudible] some people do and of course if you don't want to do the dishes, you know, there's another good reason to pretend that you're sleepy as well.