Sunday, February 10, 2008

7 Health Myths Even Doctors Believe

1. You should drink at least eight glasses of water a day.
This advice, often found in the popular press, probably originated from advice given in 1945 stating that a suitable allowance of water per day for adults is 2.5 liters (which is 10.14 cups). The statement also added that most of this quantity is found in food--but that part seems to have been forgotten. Thus, it's interpreted as eight glasses of water a day. Remember, drinking too much water can actually be harmful, resulting in water intoxication, hyponatraemia and even death.
2. We use only 10 percent of our brains.
Erroneously credited to Albert Einstein, this myth is cited by everyone from physicians to comedians. But they're wrong! MRI and PET scans show that there are no dormant, inactive areas of the brain. Detailed probing of the brain has never revealed the non-functioning 90 percent.
3. Fingernails and hair grow after death.
Johnny Carson even perpetuated this myth when he joked, "For three days after death hair and fingernails continue to grow, but phone calls taper off." Forensic anthropologist William Maples told the British Medical Journal, "It is a powerful, disturbing image, but it is pure moonshine. No such thing occurs." However, there is a biological basis for the myth. After death, the skin around the hair or nails can retract, giving the impression that the nails or hair have grown when in fact the contrasting soft tissues just shrink.
4. Shaved hair grows back faster, coarser and darker.
Clinical trials conducted as long as 80 years ago show that shaving has no effect on hair growth. More recent research proves that shaving doesn't affect the thickness or rate of hair growth. Because shaved hair lacks the fine taper seen on the ends of unshaven hair, it can appear to be more coarse. In addition, new hair hasn't been lightened by the sun, so it seems to be darker than existing hair.
5. Reading in dim light ruins your eyesight.
Moms have long maintained that children who try to postpone bedtime by reading under the covers with a flashlight will need glasses. That's not true. Poor lighting can make it seem as if your eyes can't focus and it makes them feel dryer, but in fact such light won't permanently harm your eyesight or damage the function or structure of the eyes. Any discomfort or strain is only temporary.
6. Eating turkey makes you drowsy.
Scientific studies do show that tryptophan, which is an amino acid present in turkey, is involved in sleep and mood control and can cause drowsiness. However, turkey doesn't contain enough tryptophan to knock you out. Bet you didn't know this: Turkey, chicken and ground beef contain nearly equivalent amounts of tryptophan, while pork and cheese have more than turkey! If you're sleepy after eating turkey, chances are you ate a lot more than just the meat. Any large meal can make you sleepy--with or without turkey.
7. Mobile phones are dangerous in hospitals.
Hospitals may be plastered with warning signs against using cell phones, but not a single death can be attributed to such use. However, less serious incidents causing false alarms on monitors, malfunctions in infusion pumps, and incorrect readings on cardiac monitors, have occasionally been reported, reports the British Medical Journal.