Sometimes even doctors are duped, say Rachel C Vreeman and Aaron E Carroll
Physicians understand that practicing good medicine requires the constant acquisition of new knowledge, though they often assume their existing medical beliefs do not need re-examination. These medical myths are a light hearted reminder that we can be wrong and need to question what other falsehoods we unwittingly propagate as we practice medicine. We generated a list of common medical or medicine related beliefs espoused by physicians and the general public, based on statements we had heard endorsed on multiple occasions and thought were true or might be true. We selected seven for critical review:
We use only 10% of our brains
The belief that we use only 10% of our brains has persisted for over a century, despite dramatic advances in neuroscience. Some sources attribute this claim to Albert Einstein, but no such reference or statement by Einstein has ever been recorded. This myth arose as early as 1907, propagated by multiple sources advocating the power of self improvement and tapping into each person’s unrealised latent abilities. But this really makes little sense—what is the other 90% supposed to be doing? Nothing? C'mon!
Evidence from studies of brain damage, brain imaging, localisation of function, microstructural analysis, and metabolic studies show that people use much more than 10% of their brains.
Eating turkey makes people especially drowsy
The presence of tryptophan in turkey may be the most commonly known fact pertaining to amino acids and food. Scientific evidence shows that tryptophan is involved in sleep and mood control and can cause drowsiness.
The myth is the idea that consuming turkey (and the tryptophan it contains) might particularly predispose someone to sleepiness. Actually, turkey does not contain an exceptional amount of tryptophan. Turkey, chicken, and minced beef contain nearly equivalent amounts of tryptophan, while other common sources of protein, such as pork or cheese, contain more tryptophan per gram than turkey.
Other physiological mechanisms explain drowsiness after meals. Any large solid meal (such as turkey, sausages, stuffing, and assorted vegetables followed by Christmas pudding and brandy butter) can induce sleepiness because blood flow and oxygenation to the brain decreases, and meals either high in protein or carbohydrates may cause drowsiness. Accompanying wine may also play a role.
People should drink at least eight glasses of water a day
The advice to drink at least eight glasses of water a day can be found throughout the popular press, but there is no medical evidence showing that eight glasses is the proper amount. Just bunk! Even though I'm pretty sure water is very good for you—just don't drink excessive amounts of it, since that can be dangerous, resulting in water intoxication, hyponatraemia, and even death.
Reading in dim light ruins your eyesight
The fearful idea that reading in dim light could ruin one’s eyesight probably has its origins in the physiological experience of eye strain. Suboptimal lighting can create a sensation of having difficulty in focusing. It also decreases the rate of blinking and leads to discomfort from drying, particularly in conditions of voluntary squinting. The important counterpoint is that these effects do not persist.
The majority consensus in ophthalmology, as outlined in a collection of educational material for patients, is that reading in dim light does not damage your eyes. Although it can cause eye strain with multiple temporary negative effects, it is unlikely to cause a permanent change on the function or structure of the eyes. Hundreds of online expert opinions conclude that reading in low light does not hurt your eyes.
Hair and fingernails continue to grow after death
Morbid information about the body captures the imagination and reinforces medical mythology. Johnny Carson even perpetuated this myth with his joke, "For three days after death, hair and fingernails continue to grow, but phone calls taper off." To quote the expert opinion of forensic anthropologist William Maples, "It is a powerful, disturbing image, but it is pure moonshine. No such thing occurs."
Shaving hair causes it to grow back faster, darker, or coarser
Another common belief is that shaving hair off will cause it to grow back in a darker or coarser form or to grow back faster. It is often reinforced by popular media sources and perhaps by people contemplating the quick appearance of stubble on their own body. Pure BS.
Strong scientific evidence disproves these claims. As early as 1928, a clinical trial showed that shaving had no effect on hair growth. More recent studies confirm that shaving does not affect the thickness or rate of hair regrowth. The new hair has not yet been lightened by the sun or other chemical exposures, resulting in an appearance that seems darker than existing hair.
Mobile phones create considerable electromagnetic interference in hospitals
After publication of a journal article citing more than 100 reports of suspected electromagnetic interference with medical devices before 1993, the Wall Street Journal published a front page article highlighting this danger. Since that time, many hospitals banned the use of mobile phones, perpetuating the belief. Despite the concerns, there is little evidence.
Much of this information was originally published in Mixed messages: Medical myths by Rachel C Vreeman, fellow in children’s health services research & Aaron E Carroll, assistant professor of paediatrics
BMJ Publishing Group
http://www.bmj.com/cgi/content/short/335/7633/1288
Thursday, March 19, 2009
Medical Myths
A list of common medical or medicine related beliefs espoused by physicians and the general public
