The Medical Minute: Debunking 'old wives' tales' about health

August 10, 2012, Pennsylvania State University

They’ve been repeated for decades, maybe even hundreds of years – so long that even some physicians have ceased to question their accuracy. Lurking in magazines, children’s books, and on unsuspecting tongues, their clichéd form is often too catchy to be questioned. They are what we oftentimes refer to as "old wives' tales."

Before the advent of online health information sites, there were still many sources that willingly provided medical advice - most notoriously, the group of grandmothers, family friends and other elderly acquaintances fondly referred to as “old wives.”  And although these individuals themselves may be trustworthy, not all of their medical anecdotes are. 
 
In this edition of the Medical Minute, a group of physicians from Penn State Hershey Medical Center tackle a few of these common beliefs.
 
The phrase: “Chewing gum takes seven years to digest.”
 
According to Dr. Craig Hillemeier, chair of pediatric medicine and medical director, Penn State Hershey Children’s Hospital, gum is just as digestible as this popular falsehood. Everything -- including chewing gum -- goes through the gastrointestinal tract in three to four days whether it’s fully digested or not.
 
The phrase: “Shaving speeds , or makes hair grow fuller and darker.”
 
Dermatologist Dr. Michael Ioffreda, says hair that has never been cut has a fine, tapered end - and freshly cut hair attains a blunt, squared-off tip that is thicker than a tapered hair. The result is that a grouping of such hairs would appear fuller and darker. This fallacy, like the appearance of cut hairs, is just an illusion.     
 
The phrase: “Cracking your knuckles can cause arthritis.”
 
Orthopedic hand surgeon Dr. Michael Darowish, explains that while it hasn’t been proven that knuckle cracking definitely does not cause arthritis, it’s unlikely. As joints are stretched, such as when someone cracks their knuckles, the space within the joint increases. Because the joint is a closed space, this increase in volume is associated with a loss in pressure, which causes gases to come out of the fluid in the joint and “pop.”
 
However, researchers have never been able to relate knuckle cracking to forming arthritis – it’s related to age, trauma, genetics, and other systemic diseases, not environmental causes like knuckle cracking. A California physician, Dr. Donald Unger, cracked the knuckles on his left hand every day for over 60 years, but did not crack the knuckles on his right hand. He found no difference between the two hands, and was awarded the 2009 (Ig) Nobel Prize for his findings.
 
The phrase: “Drinking coffee can stunt growth.”
 
According to behavior and developmental pediatrician Dr. Cheryl Tierney, this myth was started decades ago when it was thought that caffeine in coffee may be a risk factor for bone loss; however, much of the previous research that linked caffeinated beverages and osteoporosis were made in people that also had low calcium intake, which is clearly linked to reduced bone health. These people were more likely replacing calcium-rich milk with coffee or caffeinated sodas. 
 
So, if coffee will not stunt your child's growth, should you still limit their consumption? Yes, you should. This is because of the other side effects that come with caffeine including stomach aches, nervousness, shakiness, trouble sleeping and irritability.
 
The phrase: “Wait an hour after you eat before swimming.”
 
Dr. Hillemeier says that while there is no evident danger in swimming after eating, it might be best to wait for comfort’s sake. After eating there is increased to the stomach, to facilitate digestion. But exercise causes increased blood flow to other muscles, so exercising immediately could reduce the relative blood flow to the stomach and possibly cause cramping.
 
And as for apples? Apples and other fruit, in moderation, can be a good part of a healthy diet. By eating apples in combination with other healthful foods, it may be possible to moderate illness and other medical problems that may spark the need to visit a doctor.  

Explore further: Losing weight, keeping it off might require distinct skill sets

More information:
The Medical Minute is a weekly health news feature brought to you by Penn State Milton S. Hershey Medical Center.

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