Demand soars for vitamin D

CBC News - Health - Demand soars for vitamin D: "Some consumers and doctors are becoming convinced vitamin D can help reduce the risk of a long list of diseases, despite a lack of gold-standard research proving it.

A growing body of research suggests that supplements of the so-called sunshine vitamin may reduce the risk of multiple sclerosis, diabetes and breast and prostate cancers.

But much of the research comes from observational studies rather than placebo-controlled trials — the highest standard in health research. Such rigorous trials to prove vitamin D's preventive benefits are expensive, and since vitamins can't be patented, pharmaceutical companies have no financial incentive to do the research."