Dr. John Faul:

I thank the Deputy for an astute question. The effects of vitamin D are essential. It is a vitamin, which is a vital amine. It is required for someone to be alive. The original studies, which we cannot do in humans, were done in animals at the turn of the century and involved withdrawing animals from sunlight and nutrient vitamin D. One of the problems with human studies is that even if we tell people not to take vitamin D supplements, if they go out in the sunshine, they will get vitamin D. Dr. McCartney said that what is done in animal studies would be unethical in human studies. If one withdrew animals from sunshine and gave them a particular diet such as that the famous single-grain experiment, which involved giving animals either corn, oats or wheat, they would not survive. The animals who did the best were those fed corn. It was worked out by scientists at the time - Steenbock et alin Wisconsin, details of which I can share with the committee - that it involved ultraviolet radiation of the food itself. Even irradiating the food with ultraviolet light let the animals survive and thrive. If one did not do this, the animals would be infertile and would not thrive.

The effects of vitamin D are thought to be beneficial in humans. In fact with regard to the entire cereals industry in the US involving companies like Kellogg, Quaker Oats bought the patent for irradiating cereals so it could say there was vitamin D supplementation of its cereals. As the members are aware, Quaker Oats is a well-known cereal manufacturer in the US. It was based on that scientific knowledge that vitamin D is good for us and people should take it on a daily basis.

Regarding the question about Guillain-Barré syndrome, I agree with my colleagues that we do not have enough data on that. What we can tell the Deputy is that in the case of animals, on whom we can do experiments, animals that are vitamin D-deficient or vitamin D knockout mice have enhanced autoimmune encephalitis, an immune response that leads to a form of neurologic disease, which is the classic model. We would guess from the models of animals that it would be worse if one was vitamin D-deficient. Obviously, Guillain-Barré syndrome is uncommon and is very difficult to predict but that is what we would say.

We would also say that multiple sclerosis is similar to vitamin D deficiency and has been associated with it. I can send the members papers on this. If someone is vitamin D deficient, he or she is much more likely to get multiple sclerosis, which is a very similar type of neurologic disease to Guillain-Barré syndrome. I know it is not quite the same syndrome but it is a very similar type of neurologic disease that is affected by the immune system. I do not think fears of Guillain-Barré syndrome should push us off giving vitamin D supplementation to our patients.