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Most doctors are dubious about the merits of supplements, pointing out that many of them have no evidence to suggest that they are safe, or that they work as advertised. If that sounds like fussiness, it is actually the voice of bitter experience. Medicine is full of treatments that looked good on paper, but turned out to be useless—or even harmful—in the real world.
This week’s column
is about one recent example: vitamin D. Doctors already knew that the “sunshine vitamin” was vital for a healthy body. A lack of vitamin D famously leads to rickets, in which bones soften and deform. But a string of studies—some observational, some trials in cells or lab animals—suggested it might have other benefits, too, from helping to prevent some cancers to treating multiple sclerosis.
The column goes into the details. But suffice it to say that, when scientists tested vitamin D supplements on tens of thousands of people, none of those hoped-for benefits materialised. The theory was good. The initial studies were sound. But the idea that vitamin D supplements were good for you seems to have been simply wrong.
The uncomfortable reality is that despite all the modern wonders of MRI scanners, molecular biology, genetic studies and robot surgery, the human body is still so poorly understood that the only way to reliably tell whether a medicine or a supplement actually works is to try it and see—and to do so rigorously, in a well-run clinical trial. That will not stop the supplement industry claiming all sorts of benefits for its latest product. But it ought to give its customers pause when deciding whether to believe them.
Do you take vitamin D supplements? Vote in our poll below and let us know. And tell us what other supplements you take that you think are worth it at
wellinformed@economist.com.
We might feature you in next week’s newsletter.
Last week we asked whether the
growing body of evidence
suggesting that drinking very hot beverages increases the risk of oesophageal cancer will change how you take your tea and coffee.
Almost a third (28%) said they would now wait for their drinks to cool a bit. An even larger number said they would not need to change their behaviour as they already like their brews lukewarm. A defiant 22%, however, said they would drink them as hot as ever, with another 10% saying they wanted to see more research before making any changes.
Several of you, including
Mark,
Richa,
and
Sean
said they would let their drinks cool down from now on, or even stop drinking hot beverages altogether. Writing from Jakarta,
Frederik
says he usually waits for his coffee to cool as the “aroma and flavours become more pronounced” as the temperature drops.
Peter
in Sydney, however, says he can’t drink lukewarm coffee but has “survived 83 years without esophageal cancer”. In North Carolina,
Stanley
says he is 67, drinks two cups of hot coffee each morning “hot from the brewer”, and sees no reason to change now. Until next week. | 
