The sunshine vitamin

Even in Canada, most of us can get enough vitamin D during the summer simply by getting outside for 10 or 15 minutes daily in the midday sun. But when winter returns, should you start popping megadoses of vitamin D supplements to keep your levels up? After all, a recent meta-analysis added protection from cold and f lu infections to the list of potential benefits. But a new study by researchers at Liverpool John Moores University in Britain, published in Medicine & Science in Sports & Exercise, offers a note of caution: professional athletes who took 70,000 IU of vitamin D per week suffered adverse effects that, in some cases, left them with lower vitamin D levels than those taking lower doses. A typical drugstore supplement contains 1,000 IU; Graeme Close, the senior author of the study, suggests a default of 2,000 IU per day in the winter for those living in the northern hemisphere, and “sensible sun exposure” in the summer.