Did your mother ever tell you to eat your spinach so that you could grow muscles like Popeye? Were you ever warned that if you frowned, you'd be ugly for the rest of you life? Do you believe that if you swim right after eating, you'll get cramps?
Is there any truth to old medical folklores? ACSH Advisor Manfred Kroger, Ph.D., Professor of Science, Technology and Society at The Pennsylvania State University, states that most such folklores are false. "Some of these tales stem from three thousand years ago....But there's always a bit of fire to the smoke," says Dr. Kroger. What makes American medical folklore particularly fascinating, says Carol Ann Rinzler, M.A., author of Feed a Cold, Starve a Fever: A Dictionary of Medical Folklore and more than ten other books, is that its sources are multitudinous and geographically diverse.
We asked Dr. Kroger and several health professionals to comment on some folkloric recommendations, warnings, and beliefs:
Wait for one hour after eating before you swim.
"While common sense dictates avoiding vigorous physical activity after a large meal, wading in an ocean or a swimming pool after eating is safe," says gastroenterologist and ACSH scientific advisor Michael Kirsch, M.D. ACSH director Reimert T. Ravenholt, M.D, M.P.H., adds: "This advice has been around for many decades....I've never seen any really solid evidence of harm from moderate swimming after moderate eating, but I would certainly recommend against swimming after eating a heavy meal with alcohol."
Don't go outdoors with your hair wet, or you'll catch a cold.
Dennis J. Cunniff, M.D., an infectious-disease specialist at the New Jersey Medical School, Newark, describes the common cold as a seasonal ailment "unrelated to wet heads or lack of proper clothing." Cold viruses, he states, "are passed primarily by sneezing or contact with another person's mouth or hands." Concerning whether going outdoors with wet hair does any harm, ACSH's Dr. Ravenholt, an epidemiologist, adds: "There would be no harm in going outside with wet hair during summer. But you'd be a fool to go out with wet hair during an arctic winter. Your hair would freeze, and chilling has some implications for increased respiratory illness."
Wearing tight hats causes hair loss.
Probably not, says Alice Gottlieb, M.D., Director of Clinical Research at the Robert Wood Johnson Medical School in New Brunswick, New Jersey. But, says Gottlieb, "if you pull your hair, wear it in a ponytail, or wear it in cornrows, it can cause hair loss."
If you contort your face, it will stay contorted.
If you continually frown over many years, perhaps you will develop permanent wrinkles in your brow, says Dr. Gottlieb. "But if you just make a stupid face for a few minutes, it's untrue." According to Rinzler, "Our faces really do 'freeze' (or wrinkle) into a pattern of creases we create whenever we smile, frown, talk, and so on. While there is no way to avoid wrinkles entirely as we get older, it is trite but true to point out that smiling which uses fewer muscles than frowning really does make fewer wrinkle lines."
If you cross your eyes, you may stay cross-eyed.
False, says James G. Gorman, Jr., D.O., Assistant Professor of Ophthalmology at the University of Medicine and Dentistry of New Jersey-School of Osteopathic Medicine. According to Dr. Gorman, keeping your eyes crossed for a while may cause a temporary spasm of the eye muscles, but this condition usually passes shortly. The condition called "cross-eye" is usually one that begins at birth and is unrelated to crossing the eyes voluntarily.
Don't read in the dark.
Good advice, says Dr. Gorman. As one ages, he explains, one needs more light to see clearly. "A young person may be able to read in the dark, but it can cause undue strain on the eyes," states Dr. Gorman.
Don't sit too close to the television, or you'll lose your eyesight.
Watching television at close range does not necessarily cause, but may indicate, health problems, states Dr. Gorman. "Sometimes children want to be close for sound, but maybe the child has difficulty seeing the screen from a distance and can only see clearly when up close," he explains.
If you have a fever, apply a cloth soaked in rubbing alcohol to your forehead.
According to infectious-disease specialist Dr. Cunniff, rubbing alcohol on the forehead won't moderate a fever or even prevent its worsening, but it should cool the forehead and thus contribute to comfort. ACSH director Dr. Ravenholt states: "Alcohol evaporates quickly and tends to decrease body temperature. But this would have no particular value for a moderate fever. . . . [I]f the person has a very high fever [however], above 103 degrees, the alcohol swabbing might have some value in making both the patient and family feel better."
Cracking your knuckles will make them bigger.
Barry Poris, Ed.D., who chairs the Physical Education Department at Long Island University's Brooklyn campus, states that cracking knuckles neither enlarges them nor does any harm. Chiropractic reformer John Badanes, D.C., Pharm.D., partially agrees:
[T]here is no evidence that habitual knuckle-cracking leads to arthritis....This, however, doesn't mean that [people] can't injure their finger joints in their popping-enthusiasm by spraining capsular ligaments and/or cracking cartilage surfaces within these synovial joints. But casual and habitual popping doesn't appear to lead to anything much more than...more knuckle cracking.
Dr. Badanes cites a controlled study published in the May 1990 issue of Annals of the Rheumatic Diseases. The researchers had investigated the relationship between habitual knuckle cracking and hand health in 74 symptomless patients aged at least 45. They had concluded that, although the incidence of arthritis of the hand among the habitual knuckle crackers and among the non-knuckle-crackers had been similar, habitual knuckle cracking results in "functional hand impairment": hand swelling and lower grip strength.
Says orthopedic surgeon John Waller, M.D., who is affiliated with New York City's Lenox Hill Hospital:
What happens when you crack your joints and it's usually people who are double-jointed or loose-jointed who tend to do this is that [you]...literally open up the joint and...[create] a negative pressure in the joint, and nitrogen comes out of the blood and pops into the joint. And that's what makes the pop. That's why you can't do it to the same joint twice in a short period of time....
Parents don't like this habit, and they tell their kids not to crack their knuckles because they'll get arthritis, to try to scare them out of it.
Swallowed gum will make your stomach walls stick together.
This is just silly, states food scientist Dr. Kroger. Chewing gum is partially digestible, he says. "The chickle...and other food additives [in chewing gum], when they hit the stomach acid which is like toilet-bowl cleaner will probably liquefy." He adds:
There is no such danger, nor has any such danger ever been demonstrated....[though] some other foods or powders...have clogged up the passageway leading into the stomach [the esophagus]. If certain tablets aren't swallowed properly with water, they may get stuck in the esophagus. But that is a very dry area and if [the deposit] builds up, access to the esophagus may be gone. But chewing gum won't stick to the esophagus, because we don't swallow a pound at a time.
Toasting bread lowers its calories.
False, according to Dr. Kroger. He explains:
The color and flavor change. But the only thing that happens in the toaster is that the water disappears. It's the same with [grapes and raisins]. They are totally identical in nutrients and calories, and differ only in weight, because we've removed the water. And even the grape changes color a little bit. It's darker because of oxidation. And that's what the browning of toast is.
Oatmeal "sticks to your ribs."
Dr. Kroger states that oatmeal is not especially conducive to increases in body weight. It is oatmeal's inexpensiveness and fiber content that distinguish it.
Drinking coffee or tea will "stunt your growth."
"There's no evidence that it [coffee or tea] stunts growth either in humans or in animals," says Dr. Kroger. "Now if you don't eat a balanced diet and you drink coffee, you will have stunted growth. But it will be the result of not eating properly."
Susan Narod, M.I.A., is a freelance medical writer who lives in New York City.
(From Priorities, Vol. 9, No. 4)