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On Thanksgiving, we destroyed the myth that turkey makes you sleepy. But there are lots of holiday myths, and in this episode of Healthcare Triage, we take apart some more. These all come from a paper Aaron co-wrote in the BMJ. All the references for the studies he talks about are there:

Happy holidays!

John Green -- Executive Producer
Stan Muller -- Director, Producer
Aaron Carroll -- Writer
Mark Olsen -- Graphics
At Thanksgiving I spent some time railing against the myth that turkey makes you sleepy but that’s far from the only myth plaguing our holiday landscape so let’s kill some more. Welcome to Healthcare Triage.


Holiday Myth #1: Poinsettias are poisonous. I’ve never bought a poinsettia before, including this one, but evidently they’re pretty popular at this time of year. People seem to think though that they need to be concerned about kids, pets or even drunk adults around them because they’re toxic. Nope. In a study of 849,575 plant exposures reported to US poison control centers none, not one, of the 22,793 cases of poinsettia ingestion resulted in any significant issues. No-one died and the vast, vast majority of them didn’t need medical attention of any kind. In 92 of the cases children ingested substantial quantities of the plant but none needed medical treatment. Toxicologists all over the world have concluded that poinsettia exposures and ingestions can be treated without referral to a healthcare facility. But I know you’re not so easily convinced. You, and some rather sadistic researchers, are determined to find out how much of the plant you’d have to consume to make it dangerous. Those researchers, likely with your support, forced rats to eat the stuff until they died. Unfortunately they couldn’t find a toxic amount of poinsettia even after making the rats eat the equivalent of 600 leaves, that’s like a kilogram of the sap. I’m not telling you to go out and eat poinsettias, but stop worrying, they’re not poisonous.

Holiday Myth #2: You can cure a hangover with anything. It’s the holidays. If you’re not drinking already, more power to you. But there’s no way to cure a hangover. They’ve studied everything from aspirin and bananas to drugs and water. I know that you can do an internet search and find endless options for preventing or treating hangovers. You can even find “medical experts” touting magical cures. But here at Healthcare Triage we rely on science and no scientific evidence, none, supports any cure or effective prevention for alcoholic hangovers. There’s a great systematic review of randomized controlled trials, remember those, evaluating medical interventions for preventing or treating hangovers. They found no effective interventions in either traditional or complementary medicine. Yes, you can find a few small studies using unvalidated symptom scores that show minor improvements but these studies are flawed and without a good randomized controlled trial you can’t prove causality. The conclusion of the exhaustive review was that propranolol, tropisetron, tolfenamic acid, fructose or glucose and dietary supplements including borage, artichoke, prickly pear and Vegemite even all failed to cure hangovers effectively. There are some studies in rats that claim that a new hangover cure is on the horizon. But how the heck can you tell if a rat is hungover? Until they prove that these things work in humans you should beware, they’re not without risks. A study out of Australia found that a kudzu root containing “hangover cure”, and yes that’s in quotes, maybe linked to an increased risk of cancer. A hangover is caused by drinking too much.  Thus, the most effective way to avoid a hangover is to consume alcohol only in moderation or not at all. If you’re not gonna do that, just suck it up.

Holiday Myth #3: Suicides increase over the holidays. Holidays aren’t always fun, certainly not for everyone. They can sometimes bring out the worst in us. The combined stresses of family dysfunction and exacerbation's and loneliness and more depression over the cold, dark, winter months is commonly thought to increase the number of suicides. But while the holidays might be a difficult time for some, no good scientific evidence exists to suggest that there is a holiday peak in suicides. Let’s start with a study from Japan that looked at suicides between 1979 and 1994 that showed that the rate of suicide was lowest in the days before a holiday and highest in the days after it. In the United States on the other hand, a study of suicides over a 35 year period found no increase before, during or after holidays. Indeed, research suggests that people might actually experience increased emotional and social support during holidays. In the US again, rates of psychiatric visits decrease before Christmas and increase again afterwards. A smaller study of adolescents showed a peak in suicide attempts at the end of the school year, possibly reflecting a decrease in social support, but not around the holidays. Data from Ireland going from 1990 to 1998 also failed to connect suicides with the holidays. Irish women were no more likely to commit suicide on holidays than any other days. Irish men were significantly less likely to do so. It’s not the weather either. People aren’t more likely to commit suicide during the dark winter months. Around the world, suicides peak in warmer months and are actually lowest in the winter. Studies in Finland and in Hungary and in all kinds of other countries find that suicides are highest in the summer and lowest in the winter. Studies of suicides even from India show peaks in April and May. Studies from the US reflect this pattern as well with lower rates in November and December than in typically warmer months. Of course none of this evidence suggests that suicides don’t happen over the holidays, but they’re just not more likely. People should stop thinking they are.

Holiday Myth #4: You lose most of your body heat through your head. Yeah, that’s total crap. I bet some experts even told you this. I don’t care. Maybe you’ve even heard that the US army field manual for survival recommends this because, and I quote “40% to 45% of body heat is lost through the head”. If this were true, humans would be just as cold if they went without pants as if they went without a hat. But does anyone actually do that? No! And that’s not because of modesty, they could wear shorts. This myth probably began because of the military anyway. They did a study back in the day in which scientists put subjects in arctic survival suits, but no hat, and measured their heat loss in extremely low temperatures. Guess what, they got really, really cold. And because their heads were the only parts of the body that were exposed to the cold, they lost most of their heat through that part of the body. But that’s a terrible study, there were no controls. A better study would be to take people and stick various parts of their bodies in really cold water with different parts covered and uncovered and then see how much heat they lose in each case. Well someone did that study. I have no idea who volunteers for such stuff but they did it and in that controlled trial scientists found that there was nothing special about the head and heat loss. Any uncovered part of the body loses heat and will reduce the core body temperature proportionally. You lose heat through your head in the exact proportion that you head is to the rest of your body. So I guess if you have a really, really big head in proportion to your body, and I’m not pointing any fingers, you could try and make some argument about increased body surface area, but this myth would still be pretty much a lie.

It’s also not true that eating at night makes you fat, it was really due to that crock pot of Velveeta and sausage at your grandma’s house. Happy holidays.