11 Craziest Health Myths

Q: Are dental fillings that contain mercury dangerous?

A: Probably not. These dental fillings contain a mix of mercury, silver, tin, and other metals; they release tiny amounts of mercury vapor when they are placed in or removed from teeth, as well as when a person chews. Some consumer groups claim this vapor could trigger health problems, including Alzheimer's disease, multiple sclerosis, and other chronic illnesses, particularly in children, although virtually every major US health organization has declared these fillings safe.
If you have amalgam fillings, the FDA doesn't recommend you have them removed. But if they break down or require replacing, request nonmercury material, such as resin composite or gold, recommends Prevention advisor Andrew Weil, MD.
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Q: I got an e-mail that lipsticks contain lead and can cause cancer. Should I be concerned?

A: An FDA analysis of 10 different lipstick brands did detect very low levels of lead (0.09 to 3.06 parts per million), but the amount is minimal, compared with other common sources, says LuAnn E. White, PhD, a toxicologist and professor of environmental health at the Tulane School of Public Health. The permissible level for paint is 90 ppm, for example. While the FDA doesn’t regulate lead in cosmetics, the Canadian government is trying to. Their proposed standard for maximum safe levels: 10 pm.
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Q: Do you really have to stop drinking while on antibiotics?

A: It's best to keep the wine bottle corked while you're on an antibiotics regimen, says pharmacist Richard Harkness. You can't predict how your body may react. Alcohol can interfere with the absorption of erythromycin or the efficacy of doxycycline, for example. With certain antibiotics or antifungals--like cefoperazone (Cefobid), ketoconazole (Nizoral), metronidazole (Flagyl), and tinidazole (Tinda_max)--even a sip of alcohol may lead to flushing, nausea, abdominal cramps, headache, low blood pressure, rapid heartbeat, and shortness of breath.
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Q: I keep getting e-mails about açai pills for weight loss. Is there anything to them?

A: No. There's no proof that supplements made with açai help with weight loss or have any other miracle benefits. The berry is very high in antioxidants (similar to those in blueberries and red grapes) and contains some heart-healthy fats, but more research is needed before it can claim to fight cancer, lower cholesterol, or do anything else, says Lona Sandon, RD, assistant professor of clinical nutrition at UT Southwestern Medical Center.
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Q: Can cracking your knuckles cause arthritis?

A: Nope. If you're suffering from osteoarthritis in your hands, it certainly has nothing to do with this nervous tic. One study at the former Mount Carmel Mercy Hospital in Detroit compared 74 people (age 45 and older) who had been chronic knuckle crackers for decades with 226 who always left their hands alone; researchers found no difference in the incidence of osteoarthritis between the two groups.
But there are reasons to stop this annoying habit: The same study found knuckle crackers to be far more likely to have weaker grip strength and greater hand swelling, both of which can limit dexterity. As for osteoarthritis, that's more likely due to genetics and increasing age.
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Q: Can thong underwear cause infections down there?

A: “I haven't heard any complaints of infections from my patients who wear thongs, and I'm not aware of any studies linking the two,” says Prevention advisor and ob-gyn Mary Jane Minkin, MD. But in theory, it's possible, because the thin strip of fabric that forms the back of the thong sits right over the anus and has a direct line to the vagina or urinary tract, making it a potential conduit for fecal bacteria.
What's more likely, however, is that a thong can create tiny cracks in the skin between the anus and the vagina or cause other irritation to the very delicate tissues down there. However, if your thong underwear doesn’t bother you, there's certainly no medical reason to stop wearing it.
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Q: Is it true that liquid eyeliner causes sinus infections?

A: This rumor presumes that eyeliner is able to drain into the sinuses, get trapped, and cause an infection, but that's not possible, says Richard Rosenfeld, MD, chairman of otolaryngology at Long Island College Hospital.Your natural tearing process can funnel bits of makeup into the tear ducts, but they drain into the nose and out the nostrils. If you develop eye irritation and sinus symptoms after wearing eyeliner, you probably had an allergic reaction.
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Q: Does Listerine mouthwash help keep mosquitoes away?

A: No. Although Internet postings swear it's true, scientists beg to differ. Our research has found that people who sprayed Listerine on their arms were just as likely to be bitten as those who didn't use any repellent, says Grayson Brown, PhD, a University of Kentucky public health entomologist. The myth persists thanks to a strong placebo effect and because Listerine has eucalyptol, an ingredient found in some botanical bug sprays. But the concentration in mouthwash (less than 1%) is too low to have an impact.
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Q: Can muscle really turn to fat?

A: No. Fat and muscle are different tissues, and one cannot morph into the other, says Wayne L. Westcott, PhD, Prevention advisor and fitness research director, Quincy College. But sometimes it may seem like they do. That's because you start to lose muscle mass in your 30s, especially if you don't strength-train. This can slow metabolism by 3% per decade. The fat usually shows up in the spots where you once had firm muscle, like the backs of your arms.
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Q: Is it really bad to use a cell phone in the hospital?

A: The jury’s out. There's a chance that a cell phone call in the wrong spot can cause ventilators, syringe pumps, or even pacemakers to pulse incorrectly, according to a 2007 Dutch study.
But those findings countered a Mayo Clinic study a year prior that found no instances of "clinically important" interference between cell phones and medical machines. In fact, Mayo researchers advised hospitals to revise or drop their cell phone bans.
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Q: Do colon detox products work, and are they safe?

A: No, and they can be dangerous, says Richard Harkness, a consultant pharmacist and author of five books on evidence-based natural medicine. "Colon cleansing" procedures are based on the faulty theory that fecal matter and toxins—such as parasites, pesticides, or chemicals—accumulate and stick to the colon wall, causing assorted ailments. In fact, fecal matter does not cling to the colon wall, and experts have found no evidence that toxins build up there.
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Between e-mail forwards, the Internet, and misinformed friends and relatives, it's become harder than ever to separate health fact from fiction. Whatever their origin, misleading health “hearsays” can cause unnecessary anxiety and distract you from wellness habits that truly deserve your time and energy.
Here, the biggest watercooler myths and what’s true, what’s misunderstood, and what’s just downright wrong.