Vitamin D study
Good story in the Herald about a randomized trial of Vitamin D supplementation being run in New Zealand. Healthier people tend to have higher vitamin D levels in their blood, but for other vitamins this hasn’t turned out to mean that supplements are helpful. We don’t know for vitamin D, and we need to find out.
Long-time readers may remember that I’m betting against the vitamin, but I’d be very happy to be proved wrong.
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 »
You say we don’t know where vitamin D supplements work, except that there are already quite a lot of large randomized trials that have looked at the various outcomes (especially if you include trials of calcium and vitamin D), and pooled analyses of these trials show no benefit- at least for fracture, cancer and cardiovascular disease.
This trial will not be considered in isolation but as part of a systematic review/meta-analysis of existing results. The important question is whether it is large enough to substantially influence these pooled analyses. I suspect it is not. So even if the trial were to show effects of vitamin D, it is most likely the updated meta-analyses will still continue to show no benefit.
12 years ago
Yes, I suppose so.
It’s diabetes where new randomised evidence is most interesting. I suppose since the observational associations are really very strong, it’s possible that the meta-analyses already rule them out, too.
12 years ago