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Jul. 09, 2011

Swimming After Eating (And Other Common Summer Health Myths)

by Kaitlyn Gerber

Click to enlarge images

By Kaitlyn Gerber, Carleton College

With the warmer weather comes a variety of so-called "health tips" for surviving the summer months. But which of these are really true, and which are simply urban myths?

Myth#1: Swimming less than an hour after eating is dangerous.

This common claim has kept many swimmers out of the water throughout the decades. Theoretically, it’s possible: digestion requires large amounts of blood to provide oxygen, so swimming directly after a large meal could lead to muscle cramps if there is not enough blood left over to supply muscles with oxygen. However, experts have since concluded that this legend is simply that – a myth. Recreational swimmers may get the occasional calf cramp, but there has never been a documented case of drowning due to food-related cramps. In fact, at least one study that examined all drownings in the United States found that fewer than one percent of all drownings occur within an hour after the person ate a meal.

Much more dangerous, however, is swimming after consuming an alcoholic beverage. According to the CDC, alcohol use and intoxication is associated with up to half of all adolescent and adult deaths that occur while swimming recreationally. “No swimming after eating” would be more appropriately phrased as “no swimming after drinking.”

Myth #2: Sunburns will “fade to a tan.”

Many people (including, until recently, this author) believe that they it is natural to burn before getting a suntan, since burns eventually fade into tan. However, in actuality, sunburns and suntans are completely different. A sunburn means that the tissue in the skin has been overexposed to UV light, causing burning and inflammation. A suntan, on the other hand, is a result of moderate UV exposure, which causes skin cells called melanocytes to release a pigment called melanin. Melanin is a darker pigment that absorbs UV light, protecting the skin from UV damage. This melanin, in turn, causes the skin to look darker, or more tan. A sunburn will not fade into a suntan because it indicates damage, and does not stimulate melanin release.

Myth #3: People with darker skin do not need to use sunscreen.

People with naturally darker skin have more melanin in their skin, so their skin is more prone to absorb damaging UV rays, protecting them from sunburns. However, it is still possible for darker-skinned people to get sunburned when overexposed to the sun. In fact, while cancer rates for those with darker skin are much lower than for people with fair skin, the death rate from skin cancer is actually higher for people with dark skin, because they are less likely to notice or be aware of skin cancer signs. Overall, it is unsafe for anyone to be in the sun for too long without any sort of protection against UV rays.

Myth #4: Salty sea water is good for cleaning cuts and other wounds.

We’ve always been told that the salt in sea water will help clean cuts. However, many experts tend to disagree. Although home-made salt water is good for disinfecting cuts, sea water contains many germs and impurities that can actually cause harm if they enter the body through an open wound or sore. People who have “compromised” immune systems, due to medications, health conditions such as diabetes, or even a common cold need to be careful when swimming with exposed wounds. Harmful bacteria are especially common in ocean areas near fisheries, farms, golf courses, or stormwater drains, because runoff often contains nutrients that promote bacterial growth. Tropical waters can also host some harsh bacteria, because warmer water encourages bacteria to grow.

This doesn’t mean, of course, that you shouldn’t go swimming if you have a skinned knee or scraped elbow. But it’s important to clean cuts properly with antiseptic or a homemade salt solution once you get out of the water.

Curious about any other common summer health "facts" that you want to see investigated? Let us know!

_____________________________\

Kaitlyn Gerber will be a sophomore at Carleton College, where she plans to major in biology. Originally from Ridgefield, CT, she likes soccer, reading, and science, especially ecology and astronomy.

About Kaitlyn Gerber

The views expressed are those of the author and are not necessarily those of Science Friday.

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