Seven Medical Myths Exposed

I have my own version of some of the myths. For example my myth is that we should drink eight cups of coffee a day to keep healthy and alert! My wife thinks I use only ten percent of my brain.
I am quite surprised at the reading in dim light myth. I always thought that was well established. I guess it is well established as a myth! The article is from the BBC.
'Medical myths' exposed as untrue

Some say we should drink at least eight glasses of water a day
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.

Medical myths

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

Dr David Tovey
Editor of Clinical Evidence journal

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 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

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.