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Despite what you may have heard, drinking eight glasses of water a day isn't the key to good health. Also, neglecting to wear a coat on a cold day won't make you sick. And — you might want to sit down for this — pregnancy doesn't last nine months.
Health-related myths are often repeated as fact, even though any diligent Google search will reveal the truth behind these fallacies. Here are 26 of the most common medical myths, debunked.
Myth: Vaccines can cause the flu (and autism).Slide 2 of 51
Myth: Vaccines can cause the flu (and autism).
Although the body can develop a low-grade fever in response to any vaccine, rumors that a flu shot can cause the flu are "an outright lie," said Dr. Rachel Vreeman, co-author of "Don't Swallow Your Gum! Myths, Half-Truths, and Outright Lies about Your Body and Health" (St. Martin's Griffin, 2009).
The flu shot does contain dead flu viruses, but they are, well, dead. "A dead virus cannot be resurrected to cause the flu," Vreeman told Live Science in 2010. As for vaccines causing autism, this myth was started in 1998with an article in the journal The Lancet. In the study, the parents of eight (yes, only eight) children with autism said they believed their children acquired the condition after they received a vaccination against measles, mumps and rubella (the MMR vaccine). Since then, rumors have run rampant despite the results of many studies. For example, a 2002 study in The New England Journal of Medicine of 530,000 (yes, a whopping 530,000) children found no link between vaccinations and the risk of a child developing autism.
Unfortunately, the endurance of this myth continues to eat up time and funding dollars that could be used to make advances in autism, rather than proving, over and over again, that vaccinations do not cause the condition, said Vreeman, who also researches pediatric conditions.Slide 3 of 51
Myth: Supplements always make you healthier.Slide 4 of 51
Myth: Supplements always make you healthier.
Vitamin supplements may be not only ineffectual but even dangerous, studies have shown. For example, a study published in 2016 showed that some older women who take calcium supplements may face an increased risk of dementia. And in a huge review of 20 years of supplement research published in 2015, researchers found that taking high doses of vitamins may be linked with an increased risk of cancer.
Aside from these possible long-term risks, reports have suggested that supplements can cause damage in the short term too. A report published in 2016 found that a man in Pennsylvania who took Ayurvedic herbal supplement developed lead poisoning. Another report, also published in 2016, showed that a 4-year-old boy in England went to the ER after taking a slew of "natural" supplements, and developing a condition called vitamin D toxicity.
"The FDA does not require supplements to be regulated in the same way that drugs are, which can be a real problem," Vreeman said in 2010. As a result, the safety of many supplements has not been rigorously studied. Furthermore, supplement bottles can sport unsubstantiated claims and even make errors in dosage recommendations, she said.
It's a better idea to get your vitamins and other nutrients from eating real food, rather than taking a pill, she said.
"A vitamin pill is not the answer," Vreeman said. "Eating more healthily in general is the answer."Slide 5 of 51
Myth: Cold weather makes you sick.Slide 6 of 51
Myth: Cold weather makes you sick.
"This myth is common around the world, but it is just not true," Vreeman told Live Science. Studies have shown we may feel more cold symptoms — real or imaginary — when we are chilled (after all, a cold is called a "cold" for a reason), but the temperature itself does not make us more susceptible to viruses. This has been known since at least 1968, when a study in The New England Journal of Medicine showed what happened when researchers exposed chilly people to the rhinovirus (one cause of the common cold).
It turned out that whether they were shivering in a frigid room or in an icy bath, people were no more likely to get sick after sniffing cold germs than they were at more comfortable temperatures.
Vreeman said that cold air also does not make a difference in people's recovery time from a cold. In fact, although the research is in its early stages, "it is possible that being exposed to cold may even help your body in some way," she said.
However, its unclear how chilly conditions might affect the germs themselves. Research has shown that two common causes of colds — rhinoviruses and coronaviruses — may thrive at colder temperatures, and that the flu may spread most effectively under cold, dry conditions.
Some scientists speculate that colds are more common in cooler months because people stay indoors more, interacting more closely with one another and giving germs more opportunities to spread.Slide 7 of 51
Myth: We use only 10 percent of our brains.Slide 8 of 51