"The Internet has given people the ability to send everyone on their e-mail lists wild stories that end up mushrooming around the world in a matter of hours," says Rich Buhler, creator of Truthorfiction.com, a website devoted to debunking false e-mail rumors. But relax: Most of those health scares hitting your in-box are a misreading of facts or a deliberate twisting of the truth.
Drink eight glasses of water a day
In 1945, the U.S. Food and Nutrition Board told people to consume eight glasses of fluid daily. Before long, most of us believed we needed eight glasses of water, in addition to what we eat and drink, every day. The Truth: Water's great, but you can also whet your whistle with juice, tea, milk, fruits, and vegetables -- quite enough to keep you hydrated. Even coffee quenches thirst, despite its reputation as a diuretic; the caffeine makes you lose some liquid, but you're still getting plenty.
Stress will turn your hair gray
The carpool, the spilled milk, the deadlines. Who doesn't believe that stress can shock her (or his) locks? The Truth: "Too much stress does age us inside and out," says Dr. Nancy L. Snyderman, author of Medical Myths That Can Kill You. It ups the number of free radicals, scavenger molecules that attack healthy cells, and increases the spill of stress hormones in your body. So far, though, no scientific evidence proves a bad day turns your locks silver.
Reading in poor light ruins your eyes
It's the commonsense refrain of mothers everywhere -- reading under the covers or by moonlight will ruin your eyesight. The Truth: "Reading in dim light can strain your eyes," Snyderman explains. "You tend to squint, and that can give you a headache. But you won't do any permanent damage, except maybe cause crow's-feet." Your overtired eyes can get dry and achy, and may even make your vision seem less clear, but a good night's rest will help your peepers recover just fine.
Coffee's really bad for you
Surely something 108 million Americans crave so much each morning couldn't possibly be good for you? Wrong. The Truth: Too much may give you the jitters, but your daily habit has a lot of positives. "Coffee comes from plants, which have helpful phytochemicals that act as antioxidants," says Stacy Beeson, a wellness dietitian at St. Luke's Boise Medical Center in Boise, Idaho. Drinking joe gives your brain a boost, too. And, despite the jolt of energy it provides, coffee has no effect on heart disease.
Feed a cold, starve a fever
The old wives' tale has been a staple since the 1500s when a dictionary master wrote, "Fasting is a great remedie of feuer." The Truth: "Colds and fevers are generally caused by viruses that tend to last seven to 10 days, no matter what you do," says Dr. Rachel Vreeman, a fellow in Children's Health Services Research at the Indiana University School of Medicine in Indianapolis. "And there is no good evidence that diet has any effect on a cold or fever. Even if you don't feel like eating, you still need fluids, so put a priority on those." If you're congested, the fluids will keep mucus thinner and help loosen chest and nasal congestion.
Fresh is always better than frozen
Ever since scientists honed in on the benefits of antioxidants, the mantra has been "eat more fresh fruits and veggies" -- implying that frozen is second-rate. The Truth: "Frozen can be just as good as fresh because the fruits and vegetables are harvested at the peak of their nutritional content, taken to a plant, and frozen on the spot, locking in nutrients," Beeson says. And, unless it's picked and sold the same day, produce at farmers' markets -- though still nutritious -- may lose nutrients because of heat, air, and water.
Eggs raise your cholesterol
In the 1960s and 1970s, scientists linked blood cholesterol with heart disease -- and eggs (high in cholesterol) were banished to the chicken house. The Truth: Newer studies have found that saturated and trans fats in a person's diet, not dietary cholesterol, are more likely to raise heart disease risk. And, at 213 milligrams of cholesterol, one egg slips under the American Heart Association's recommendation of no more than 300 milligrams a day. "Eggs offer lean protein and vitamins A and D, and they're inexpensive and convenient," Beeson says.
Get cold, and you'll catch a cold
It must be true because your mother always said so. Right? The Truth: Mom was wrong. "Chilling doesn't hurt your immunity, unless you're so cold that your body defenses are destroyed -- and that only occurs during hypothermia," Vreeman says. "And you can't get a cold unless you're exposed to a virus that causes a cold." The reason people get more colds in the winter isn't because of the temperature, but it may be a result of being cooped up in closed spaces and exposed to the spray of cold viruses.
Your lipstick could make you sick
In 2007, an environmentalist group, the Campaign for Safe Cosmetics, had 33 lipsticks tested for lead. Although there's no lead limit for lipstick, one-third of the tubes had more than the limit allowed for candy. The Truth: "The reality is that lead is in almost everything," says Dr. Michael Thun, head of epidemiological research for the American Cancer Society. "It's all around us. But the risk from lead in lipstick is extremely small." In fact, lead poisoning is most commonly caused by other environmental factors -- pipes and paint in older homes, for instance.