Many of us have tried-and-true rules for avoiding illness. But if you subscribe to the theory that heading outside with wet hair will make you sick, bubbles in fizzy drink can make your bones brittle or chili peppers can cause stomach ulcers, think again. Those ideas just aren't true, says a new book that explores popular health myths.
According to Don't Cross Your Eyes ... They'll Get Stuck That Way, there's no evidence that getting chilled increases the risk for catching a cold; studies find no link between bone weakening and carbonation; and capsaicin, the heat-inducing substance in chili peppers, has actually been shown to reduce ulcer-causing acid in the stomach, not increase it.
As for mothers who admonish their children about the dangers of intentionally crossing their eyes, not so fast. Yes, doing it for an extended period of time can strain eye muscles, perhaps even resulting in eye spasms, but it's a myth that your eyes will get stuck in that position, write Aaron Carroll and Rachel Vreeman, the two paediatricians and Indiana University School of Medicine researchers in a follow-up to their 2009 hit, Don't Swallow Your Gum! Myths, Half-Truths and Outright Lies About Your Body and Health.
Ready to lose some myths? Read on.
• Why are these health myths so widely accepted?
Vreeman: Some have an element of truth, like the idea that eggs give you high cholesterol. Eggs do have a significant amount of cholesterol in them, but it's the link between the egg and the high level of cholesterol in your blood that is a lot more sketchy. Other myths you hear from experts or people you trust, your mother or your doctor, even. When we hear things from people we trust, we seem to be willing to hold on to them.
• Many myths are costly in time, energy and money.
Vreeman: Cold remedies are a great example of that. In the book we look at all sorts of things that people put forward as potential ways to prevent or cure colds, including echinacea and vitamin C, none of which work. People spend all kinds of money on these products in the hope that it's going to stop them from getting sick or it's going to make them better quicker when they have a cold.
Carroll: I have no trouble with people who want to try home remedies or things that are relatively inexpensive, if it's not going to work. But when we medicalise some of these, or start charging people for them, then it gets to be more of an issue. Using cool mist to treat croup is an example. Hospitals [in the US] will put children in croup tents or put mist in front of them and charge you for it when there have been no studies showing a benefit.
• Your book is a fun read but includes detailed references to scientific research. Why?
Carroll: Myths are perpetuated because people with authority keep repeating them without thinking through exactly what the evidence is that holds them up. We try to show that evidence and then allow people to draw their own conclusions.
• Were there things you personally believed but now know otherwise?
Vreeman: Absolutely. One was the idea that you should stretch before exercising. I run and you hear that you should stretch first all the time. I've never been a huge stretcher, but I was shocked to see the number of studies that actually pointed to the idea that stretching did nothing to prevent injuries, it did nothing to prevent muscle soreness in people, and it may even make you perform worse.
Another was the idea that you should uncover a wound to help it heal. I'd heard that from my mother and from fellow doctors. So I was really surprised to see all the science that says uncovering a wound may actually make it heal more slowly and make it more likely to scar.
Carroll: My son would eat nothing but cheese if I allowed him, and I was always telling him that eating too much cheese would make him constipated. So finding out there's really no good evidence implicating cheese in causing constipation was shocking to me. Certainly there are people who have dietary issues with milk and dairy, but those issues usually have more to do with diarrhoea, bloating or discomfort, not constipation.
• A few remedies actually live up to their reputation. For example, aloe vera really is a good treatment for burns.
Carroll: That was one I was sure was going to turn out to be a myth, another one of those home remedies that doesn't really work. But there have been very good randomised controlled studies published in the medical literature which show it actually does help many kinds of burns to heal, and often faster than even the medicines we normally use.
• You say cellphone users can relax about brain cancer risk, even though the World Health Organisation recently labelled cellphones "possibly carcinogenic."
Carroll: The Who analysis used data that was published long enough ago that we were able to incorporate it into the book. It changes none of our conclusions. Billions of people use cellphones. If there were a major association between cellphone use and brain tumours, we'd really be expecting to see a rise in brain cancers, and we're just not seeing that.
