Supplement pushing
The Herald has a Daily Mail story about vitamin D for making you generally feel better. It’s not so long ago that the NZ media had a lot of less supportive coverage on vitamin D — Ian Reid, Mark Bolland, and Andrew Grey won the Prime Minister’s Science Prize last year for their work showing that calcium and vitamin D aren’t all they’re cracked up to be.
The story does have some new evidence.
In the study, by a medical team in Edinburgh, volunteers were asked to cycle for 20 minutes. They were then given either a placebo or vitamin D and, two weeks later, were asked to cycle for 20 minutes again.
Though the Scottish study only had 13 participants, its lead author, Dr Emad Al-Dujaili, of Queen Margaret University, is convinced of its importance.
In fact, if you look up the conference book where the research was presented (it’s not published yet, just publicised) you see that only 8 of the 13 got vitamin D. Also, the data analysis didn’t compare the people getting vitamin D to the people getting placebo, it compared the people getting vitamin D before and after — making it no longer a controlled trial. You may remember Dr Al-Dujaili from our coverage of his pomegranate juice research, in similarly small studies that tended not to end up being published.
The piece ends
Grand claims are made for Vitamin D these days, but I will say this: I am going to carry on taking these supplements whole-heartedly because they really do make me feel better. And that is pure, unadulterated sunshine.
That’s a good enough reason for her to take them. It’s not a good enough reason to tell the world to take them, or to single out one tiny study of eight people in Scotland over all the larger randomised trials.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »