Medical Myths Exposed

[johnnymk]

http://news.bbc.co.uk/2/hi/health/7153880.stm

THE SEVEN MEDICAL BELIEFS
Drink at least eight glasses of water a day
We use only 10% of our brains
Hair and fingernails continue to grow after death
Reading in dim light ruins your eyesight
Shaving causes hair to grow back faster or coarser
Mobile phones are dangerous in hospitals
Eating turkey makes people especially drowsy


Some claim drinking eight glasses of water a day leads to good health, while reading in dim light damages eyesight.
Others believe we only use 10% of our brains or that shaving legs causes hair to grow back thicker.

But a review of evidence by US researchers surrounding seven commonly-hold beliefs suggests they are actually "medical myths".

Some are utterly untrue, while others have no evidential proof, the British Medical Journal reports.

Researchers from the Indiana University School of Medicine in Indianapolis hunted medical literature for evidence on each claim.

They found no evidence supporting the need to drink eight glasses of water a day.

In fact, studies suggest that adequate fluid intake is often met by drinking juice, milk, and even caffeine-rich tea and coffee.

Data also suggests drinking excessive amounts of water can be dangerous.

The belief that we only use 10% of our brains appears to be completely untrue.

Studies of patients with brain damage suggest that damage to almost any area of the brain has specific and lasting effects on mental, vegetative and behavioural capabilities.

Absence of evidence does not necessarily mean absence of effect

Brain imaging studies also show that no area of the brain is completely silent or inactive.

And the belief that hair and fingernails continue to grow after death may be an optical illusion caused by retraction of the skin after death.

The actual growth of hair and nails requires a complex interplay of hormonal regulation not present after death.

Again, illusion may be to blame for the belief that shaving hair causes it to grow back faster, darker, and coarser, report author Rachel Vreeman told the BMJ.

The stubble resulting from shaving grows out without the finer taper seen at the ends of unshaven hair, giving the impression of thickness and coarseness.

Again, expert opinion is that reading in dim light does not damage your eyes. And there is little evidence to support the banning mobile phones from hospitals on the basis of electromagnetic interference.

Finally, eating turkey - and the tryptophan amino acid it contains - does not make people especially drowsy.

Indeed, turkey, chicken and minced beef contain similar amounts of tryptophan.

The researchers explained: "Any large meal can induce sleepiness because blood flow and oxygenation to the brain decrease, and meals rich in protein or carbohydrate may cause drowsiness. Wine may also play a role."

Dr David Tovey, editor of Clinical Evidence journal, said: "The difficulty is it is often hard to disprove a theory.

"On the flip-side, absence of evidence does not necessarily mean absence of effect.

"Where reliable evidence becomes really important is in helping people make serious decisions about harms and risks.

"Many of these 'myths' are innocuous. However, we are still finding evidence that runs contrary to current practice and what we expect."

He gave the example of the relatively recent U-turn in advice over sleeping positions for babies to cut cot deaths.

Experts now recommend babies are positioned on their backs when sleeping to reduce the risk of sudden infant death.

[zenbooty]

I always took the "10% of our brains" factoid to mean we never use more than 10% of our brains at any one time. I could be wrong, I guess.

Nah.

[zippyjuan]

In fact, studies suggest that adequate fluid intake is often met by drinking juice, milk, and even caffeine-rich tea and coffee.


Be aware that cafeine is a diuretic which can take water out of your system. Beverages containing lots of sugars (including sodas and fruit drinks) can cause your body to move them more quickly through your system meaning you may abosrb less of the water in them. If you regularly consume caffeine, your body can adjust to the effect though.

I believe that the "ten percent of the brain" refers to the percent of the brain used for conscious activities like thinking. It is constantly doing other things like monitoring body functions and tracking the world around us.

[Memo]

Eh, this article is trash. There's nothing in it that common sense and about 2 seconds of thought haven't already told you.

[ShawnLee]

Eh, this article is trash. There's nothing in it that common sense and about 2 seconds of thought haven't already told you.
I agree generally, but mainly disagree about the brain use thing. I heard until I was well into high school about the 10% thing, and this from teachers who supposedly knew better.

Even some profs from college passed on this "knowledge" until I corrected them afterwards. Especially considering the pop culture surrounding this belief (stories or movies about people who acquire special abilities because they can use more than 10% of their brains), I'm all for teaching people about this.

Correct me if I'm wrong (anyone), but I understand that the 10% comes from a misunderstanding about how the brain functions and that only a certain part of it is involved in actual applied cognitive thinking while other parts of it control mood, automatic body regulation such as heat regulation and heartrate and breathing, while other parts do still other things.

[WhiskeyPapa]

Hair and fingernails continue to grow after death


Does anyone actually believe this? It seems I see it pop up on these types of lists quite regularly, but I've never once in my life heard someone say "I always thought that was true."

I think it was probably something really stupid people believed 100 years ago, and for some reason still lives on as one of the "common misconceptions" that really isn't that common.

[chrissy]

I was told when I was a kid that hair and nails continue to grow. it didn't seem true then, but I know a bunch of us believed it at that time.

[Napoleon54]

Correct me if I'm wrong (anyone), but I understand that the 10% comes from a misunderstanding about how the brain functions and that only a certain part of it is involved in actual applied cognitive thinking while other parts of it control mood, automatic body regulation such as heat regulation and heartrate and breathing, while other parts do still other things.

The body's autonomic functions (heartrate, breathing, etc) require practically zero processing power and are controlled by the medulla oblongata and brain stem... these are things even worms can do. The human brain consumes a huge portion of the body's resources- nutrition, oxygen, etc. The brain is biologically a very expensive organ. What do we need all that brain for? We never would've developed brains of this size if they didn't give us a powerful survival advantage. Even things like coordination and visual processing, things one might think are highly resource intensive, are done largely by the cerebellum. What's the value of having a huge cerebrum, aka "grey matter"? As far as I know, we don't really know nearly as well as we'd like to. Memory? Language? Social interactions? There's a lot we don't know about the brain, what it does, and how it does it. IMHO there's a lot of biologically costly tissue in our heads that doesn't have a well-understood biological justification.

I mean... the fact that it's there is proof that it must be important for some reason... but exactly what that is, is a huge question (at least IMHO). Aside from cognative function, self-awareness, etc, the brain functions of humans and other animals are very similar. However, comparing humans to other animals, there are substantial differences in brain size (relative to body size) and the amount of the body's resources that are devoted to the brain. The major difference between humans and animals is cognative function, so one would assume that that's what our brains are needed for.