It's not like we'd argue with our grandmas or moms -- but, really, does going outside with wet hair give you a cold? Josh Kosowsky, M.D., who works at Boston's Brigham and Women's Hospital and co-authored "When Doctors Don't Listen" (www.whendoctorsdontlisten.com), did some research and came up with answers for us.
Going outside with a wet head gives you a cold:
"I want to believe this because experientially it feels like it's true. But it turns out it's not. Short periods of being outside with wet hair or scalp won't give you a cold."
Indoor tanning boosts your vitamin D:
"Exposure to sunlight does promote vitamin D, but is ultraviolet light in a tanning bed the same thing? The risk of skin cancer from using them makes it a bad idea."
Eating carrots improves your vision and turns your skin orange:
"Both of these are true. That doesn't mean eating a bushel of carrots every day gives you X-ray vision and you'd need to eat ridiculous amounts to turn orange. But carrots do contain beta-carotene, which the body turns into vitamin A, which is necessary for healthy vision."
Standing by a microwave gives you cancer.
"This one has been pretty much debunked. The likelihood of radiation leaking from a microwave oven is trivial."
Cracking your knuckles gives you arthritis:
"I tell my kids this all the time simply because it's really annoying! But there's no known correlation."
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Food dropped on the floor is OK to eat before five seconds pass:
"You don't need to be a doctor to work that out. There's nothing legitimate about it. But much of what we eat is contaminated by bacteria. Our hands have bacteria. Our stomach acid kills most bacteria."