Sunshine and Multiple Sclerosis – The Role of Vitamin D (Part 1)

By Brett Drummond

For a long time, it has been known that both genetics and the environment play a role in determining how likely a person is to develop multiple sclerosis (MS). As technology advances, more and more genes are being identified that are related to increasing an individual’s risk factor for MS. On the other hand, what environmental triggers are involved are still quite unclear.

Looking at the worldwide incidence of MS on a world map, one thing becomes immediately clear. The rate of people affected by the disease increases the further you move away from the equator. What’s more interesting about this is data suggesting that the risk associated with where in the world you live is only relevant for the first 15 years of your life. For example, if you were to live in a high risk area (e.g. Tasmania) until you were 20 and then move to somewhere nice and tropical on the equator, your risk of developing MS would still be at that high level. On the other hand, if you were to grow up near the equator and then move to Tasmania, you would still maintain that low level risk for the rest of your life.

This geographical phenomenon has recently been hypothesised to be related to sunlight exposure and therefore, levels of Vitamin D. The production of Vitamin D in our body begins through activation by UV light, which we get from the sun. Vitamin D has many roles in our body. These include maintaining appropriate levels of calcium and phosphate (important for growth and development of bones) and has many effects on the immune system (including playing a role in inflammation).

While Vitamin D is a nice way of explaining the different risks associated with geographical location, specific evidence for its role is still being produced. A recent population study did suggest that sunlight exposure during childhood did alter a person’s chance of developing MS. However, the most compelling piece of evidence so far links a genetic factor with our environmental factor. In our body, we have molecules on the surface of our cells (called MHC or HLA molecules) that play an important role in the immune system. These molecules are constantly presenting small pieces of proteins to the immune system so that it can maintain surveillance on whether or not we are sick. One of these molecules has been highly linked to developing MS – in fact, it confers the greatest genetic risk. It was recently found that this molecule can be triggered by Vitamin D.

Exactly how this may lead to a Vitamin D protective effect is still unknown. We will go into more detail with this and other evidence in future articles. We are still a long way off being able to definitely say that high levels of Vitamin D can protect against developing MS, though evidence is growing that it may play a role in both multiple sclerosis and other autoimmune diseases. This opens up the possibility of using Vitamin D supplements early in life as a way to decrease the risk of developing multiple sclerosis.