Reinhold Vieth, [a] professor at the University of Toronto's Department of Laboratory Medicine and Patho-biology, ... is among the most knowledgeable people in the world on the subject of vitamin D. In the US and Canada, official vitamin D policy is set by the Institute of Medicine. And in the opinion of Vieth, the current recommendations - 200 International Units per day for people under 50, 400 for people aged 51-70, and 600 for those 71 and older - are outrageously low. Vieth and other vitamin D advocates have good reason to think there will be minimal changes made to dietary guidelines. Last December, the World Health Organisation's International Agency for Research on Cancer issued a 465-page report that concluded there was no need to raise vitamin D recommendations. The evidence favouring vitamin D is probably as good as the evidence that shows smoking is bad for you," Vieth says, explaining that just as smoking is correlated with certain cancers, so are low vitamin D levels. "But when these government officials see the same kind of evidence that deals with vitamin D as they see with smoking they go, 'Oh wait a minute. We can't really trust this.'" Vieth pauses, as though he can barely stand to talk about such a miserable state of affairs. "It's easy to say 'don't do something - don't smoke'. It's very hard to say 'take this. Take vitamin D.'"