Recent research suggests that a kid growing up in a home that's too sanitary may not get enough practice battling germs, which the immune system needs in order to learn how to properly react to bacteria and viruses that cause illness.
Too little exposure to germs can result in an immune system that doesn't know how to regulate itself, which in turn can lead to autoimmune disorders such as allergies or asthma, says Joel Weinstock, M.D., chief of gastroenterology and hepatology at Tufts University School of Medicine, in Boston. "When we're born, our immune system is a blank slate," he says. "As we grow, it learns from exposure."
This theory, called the hygiene hypothesis, has been making waves among health care professionals. This doesn't mean that cleanliness isn't important, but it's more complicated than most of us thought. There are bad germs, good germs, and some that can go either way. The trick is avoiding the bad while embracing the good. Read on for the do's and don'ts of hygiene.
Hands are the best friends a germ ever had, says Chuck Gerba, Ph.D., germ guru and professor of microbiology at the University of Arizona in Tucson. They're constantly moving, and they spread germs everywhere until you wash them off. Common sense says to wash your child's hands before meals and when they look dirty, but you should also suds up after leaving crowded areas where contagious germs linger.
With washing hands, how you do it is more important than what you do it with (but soap and warm water is the most effective combo): Rub those little paws together for 15 seconds, about as long as it takes to sing the ABC's twice. With squirmy toddlers, that's easier said than done. Elizabeth Donovan of Centreville, Virginia, always had a tough time getting her 2-year-old to wash for long enough-until she shook things up with fun soaps. "I let her make it messy by squirting lots of foam soap," Donovan says. Try a soap that's scented, shapeable, foaming, or that features your child's favorite TV character. For babies younger than 6 months, rub hands for 15 seconds with soap and a warm, wet, clean washcloth.
Antibacterial soaps aren't any more effective than ordinary ones at protecting from illness. Surprised? The FDA came to this conclusion in 2005, after Columbia University, in New York City, conducted a major study of soaps. Researchers tracked the effects of antibacterial soap versus regular soap for a year, finding no difference in the rate of fever, vomiting, or diarrhea among study participants. Remember, too, that antibacterial products kill -- you guessed it -- bacteria, but they don't kill viruses that lead to colds and flu.
On the other hand, alcohol-based sanitizers are extremely effective at killing both bacteria and viruses, and you can use them after changing a diaper in the park or at other times when a sink isn't available to wash hands. Pick one with 60 percent alcohol, and apply enough so that it covers the hands when rubbed in for 15 seconds. Sanitizers are safe for babies and kids but should be stored out of reach and applied only by a caregiver. And keep in mind: the alcohol in sanitizers kills germs, but it won't wash off dirt. So if baby's hands are visibly dirty, rub 'em down with a wet wipe first.
Kids today spend less time outside than ever before. We know the culprits: too much television and too many organized activities. TV viewing and less time outdoors are major contributing factors to obesity. But running around in a yard isn't just good for kids' waistlines, it also boosts immunity. So make time for your kids to crawl around in the grass, dig in the sand, and drive dump trucks in the dirt. Casual contact with organisms living in the soil will actually help your child's immune system grow stronger, teaching it how to fight off the harmful germs when they pop up, says Joel Weinstock, M.D., chief of gastroenterology and hepatology at Tufts University School of Medicine, in Boston.
When that buttered toast falls facedown on the floor, you want to know: Is it safe to eat? Paul Dawson, Ph.D., a professor of food science at Clemson University, in South Carolina, conducted a study in 2006 to find out. Dawson's team covered floors with lots of salmonella, dropped bologna and bread, and analyzed how many bacteria were transferred from the floor to the food over different lengths of time. The bad news? Plenty of bacteria hopped on over within the first five seconds -- not as many as after the food had been on the floor for a full 60 seconds but enough to potentially make someone ill. Since you can never be certain which invisible germs are lurking underfoot, play it safe and toss food when it takes a dive.
In most U.S. homes, you'd probably pick up fewer germs flushing a toilet than you would handling a cutting board. About 60 percent of kitchen cloths and sink faucets are heavily contaminated with a nasty combo of bacteria like E. coli and staph. On the flip side, only 15 percent of bathroom door handles and 30 percent of toilet flush handles contain harmful germs.
The problem isn't that we're not cleaning enough but that we aren't cleaning correctly, Gerba says. Getting rid of dirt doesn't always mean getting rid of germs. If you wipe down the kitchenwith a dishcloth that looks clean but has invisible salmonella growing all over it, all you've done is spread that salmonella far and wide. The most overlooked kitchen items are dishcloths and cutting boards. So change cloths at least once a week and put cutting boards in the dishwasher after each use. For floors, ask guests to leave shoes by the door. If you're worried about your little crawler, use only nontoxic floor cleaners.
You've probably noticed that children today seem to suffer from allergies and asthma more often than when you were little. Unheard of in the 1800s, allergies and asthma collectively affect about 9 percent of U.S. kids today. To help explain this increase, researchers at the University of Virginia conducted an extensive study and found that children raised for their first year of life in a home with two or more dogs or cats were almost 80 percent less likely to develop allergies than other kids. And scientists at the University of Cincinnati found that infants living in homes with several dogs are far less likely to wheeze than other babies are.
Other studies have found the same low rates of allergies and asthma among kids growing up on farms that have livestock.
Although this connection is clear, no one is sure of the explanation. Some scientists believe that frequent contact with pet dander or the bacteria found in animals' intestines trains a child's immune system to react correctly to foreign invaders. Which means: no allergies. Of course, genetics plays a big role too. So have a talk with your pediatrician before getting a pet if your family has a history of asthma or allergies.
"When I was pregnant, I swore I'd never let my son play with something that wasn't sanitized to the nth degree," says Kristen Chumley, a mom in Stevensville, Maryland. "Now my son loves to pick up dirt, leaves, and insects. I don't want to break his spirit." And there's no reason to. No matter how vigilant you are, kids get sick, and pretty often: on average, six to eight colds a year. The old adage "practice makes perfect" rings true when it comes to immunity.
Every germ your child encounters teaches his immune system how to fight unwanted invaders more powerfully and effectively. So long as a kid eats right, sleeps enough, and keeps up with his vaccines, he'll weather the colds, fevers, and stomach bug -- and grow stronger with each one. Once you've taken sensible precautions, go ahead and let it go. Enjoy watching your child share an ice cream with his sister -- or simply sift dirt in his palms.
We all want our kids to play nice, but not when it comes to slobbery sippy cups. Here's when it's safe, according to Lisa Salman, M.D., a pediatric infectious disease specialist at New York-Presbyterian Morgan Stanley Children's Hospital.
Originally published in the March 2010 issue of American Baby magazine.
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