From the New York Times:
This year [...] Dr. Aaron Carroll and Dr. Rachel Vreeman of the Indiana University School of Medicine, offer six new medical myths for the holiday season. The latest set of myths, published this month in BMJ, are commonly believed by the general public and many doctors, said the researchers. However, a search of the medical literature shows these myths aren’t true or lack evidence to support them.
1. Sugar makes kids hyperactive. The researchers cite 12 controlled studies that couldn’t detect any differences in behavior between children who had sugar and those who did not. Even when kids had a diagnosis of hyperactivity problems or were said to be more sensitive to sugar, they did not behave differently whether they ate sugar-laden or sugar-free diets. In fact, the biggest effect of sugar may be on parents. Parents rate their children as being more hyperactive if they are told the child has consumed sugar — even when the child hasn’t really had any sweets.
2. Suicide increases over the holidays. Suicides are more common during warm and sunny times of the year, studies show. There is no evidence of a holiday peak in suicides.
3. Poinsettias are toxic. Among 22,793 poinsettia exposures reported to the American Association of Poison Control Centers, there were no deaths or significant poisonings. A study of poinsettia ingestion found that when rats were given doses equal to a person consuming 500 to 600 poinsettia leaves, the plant wasn’t toxic.
4. You lose most of your body heat through your head. This is the myth that Dr. Carroll and Dr. Vreeman believed to be true. They found out that the belief likely originated with an old military study where subjects wearing arctic survival suits lost most of their body heat through their heads. But that was because the head was the only bare part of their bodies. Typically, we don’t lose more than 10 percent of body heat through our heads. The bottom line is that any uncovered part of the body will lose heat, which is why wearing a hat, even when you’re bundled up everywhere else, is important.
5. Night eating makes you fat. Studies show an association between obesity and eating more meals, but that doesn’t mean eating at night causes obesity, the doctors point out. Eating more at any time of day will cause weight gain if it results in ingesting more calories than you need.
6. Hangovers can be cured. The researchers found no scientific evidence supporting any type of cure for alcohol hangovers. Because hangovers are caused by drinking too much alcohol, the only way to avoid one is to drink very little or not at all.
Next year, the doctors plan to provide more research on medical myths in their new book, Don’t Swallow Your Gum: Myths, Half-Truths, and Outright Lies About Your Body and Health, to be published by St. Martin’s Press.
Here’s a second, earlier list (from a 2007 BMJ article by the same authors). Each statement, explain Vreeman and Carroll, is also false:
- People should drink at least eight glasses of water a day.
- We use only 10 percent of our brains.
- Hair and fingernails continue to grow after death.
- Shaving hair causes it to grow back faster, darker or coarser.
- Reading in dim light ruins your eyesight.
- Eating turkey makes people especially drowsy.
- Cellphones create considerable electromagnetic interference in hospitals.
I’ll be looking out for Don’t Swallow Your Gums.
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10 responses
When I was studying cognitive neuropsychology, we spent a little bit of time on the “we only use 10 percent of our brains” myth, trying to figure out where it came from.
According to one explanation (and this is only one among several candidates) it came from PET studies that showed that AT ANY GIVEN POINT IN TIME only about 10% of your brain is “lit up”.
This, of course, is a meaningless statistic. At any given point in time, you are only using a small percentage of your muscles, as well. And in fact, if you tried to contract every single muscle in your body simultaneously, the result would certainly not be useful to anyone. It doesn’t mean you have “untapped resources”; it merely means different parts are in operation at different times.
OK, I swear I tried to use the internets to dig up some of the studies on sugar and hyperactivity in chidren. I couldn’t find a single one. If someone can find a public link to a write-up of an actual study, please post it.
The reason I’m interested is that I VERY much want to check the methodology on this “myth debunking.” Sure, sure, I know that introspective evidence isn’t worth anything, but like many other people I “know” I get more hyper and distractable when I’ve had a lot of sugar. So that makes me a little suspicious.
And in addition to that (very weak) reason, I also can imagine a large number of problems that could come up in testing this kind of hypothesis. For example:
- did they control for base rates of sugar in childrens’ diets? Take two children who regularly get a LOT of sugar, and they may show no difference in behavior when you give one sugar and the other one a placebo, because they have a “tolerance”. Do the same comparison with two children who are adapted to low-sugar diets, you may get a different result.
- in what environment did they measure hyperactivity? one theory about hyperactivity is that it is a reduction in the filter of irrelevant information, so that it’s really “distractability”. If you take two children, one who is more distractable and one who is less distractable, and lock them both in a plain boring room with no external stimuli, then you will not SEE a difference in their hyperactivity levels. It doesn’t mean there isn’t a cognitive change that would appear under normal “real world” conditions.
….. and so on. That’s just two examples.
Maybe I’m just clinging to my “folk psychology”, but I’m not going to jump on the “oh that’s been debunked!” bandwagon just yet with some of these.
@ Greg:
At an excellent lecture I attended on debunking neuroscience myths, the “We only use 10% of our brains” was a bastardisation of the quote that “I don’t think humans use 10% of their *potential*” (note the small difference!) I’ll try and find more details later on when I have better internet access…
I wonder if the sugar myth is more to do with other additives in sweet drinks and foods. I worked for some time on a paediatric ward and vividly recall one small boy who was admitted to investigate his hyperactive behaviour. The child was almost uncontrollable on admission but calmed down completely after withdrawing his usual fruit squash for a couple of days. His usual drink contained tartrazine (E102) and I recall the consultant being quite convinced that this additive could cause hyperactive behaviour in some children.
The first one about sugar I definantly have to dispute. Have you ever given candy to a classroom of children on Haloween? Oh boy try and teach afterward. The only debunking of sugar causing hyperactivity I’ve seen is from the Sugar Association (here is a link: http://www.sugar.org/consumers/sugar_myths.asp?id=42&fragment=0&SearchType=AND&terms=myths) I’m thinking tey are a bit biased but Wasp_Box brings up a good point.
I believe the joke goes that most of lose 10% of our body heat through the head, but it’s 75% for politicians.
Wearing a hat is still one of the best ways to stay warm in the cold, because the body burns a lot of energy to keep the brain warm. A warm hat helps your whole “core” stay warm.
@Tomato Addict
you basically rephrased the exact same myth. dont you understand?
@aaaaaaaaaaaaaaaaaaa
No, you don’t get it.
The head is the only uncovered part of the body in Winter, for instance - so you do lose most of your body heat through your head THEN.
They basically say the same thing…
This is not “a myth” issue - it’s more “observational” intelligence issue. People take things for granted but that’s normal and sholdn’t be part of a “intelligent” debate, let alone myth debunking success
With many “myths”, like the “sugar high” myth. We must take into account the ‘Nocebo’ effect, just like a placebo having a positive effect a certain number of people, if you tell people that eating sugar will make them hyper-active the effect will be real to some. Children are especially susceptible to such suggestion.
See the posting on Junkfoodscience for more on this; http://junkfoodscience.blogspot.com/2009/09/how-some-food-can-make-us-sick.html
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