Vitamin D helps to control a gene variant that is known to increase the risk of multiple sclerosis (MS), the results of a new study indicate.
MS affects the brain and the spinal cord. Around 6,000 people in Ireland have the disease and it is currently the most common neurological disease affecting young Irish adults. Unfortunately there is no cure and the condition is characterised by a slowly progressing disablement.
Vitamin D is necessary for good bone health. Sunshine is the primary source of this vitamin, with the body producing it as a result of the action of sunlight on the skin. It can also be found in fortified foods and supplements.
While the causes of MS are unclear, it is widely acknowledged that both environmental and genetic factors play a role. Previous studies have shown that populations from Northern Europe have an increased risk of developing the condition if they live in areas receiving less sunshine. This supports a direct link between deficiency in vitamin D and an increased risk of developing MS.
The largest genetic effect by far comes from the region on chromosome six containing the gene variant known as DRB1*1501 and from adjacent DNA sequences.
Now UK and Canadian researchers have established a direct link between DRB1*1501 and vitamin D.
They found that proteins activated by vitamin D in the body bind to a particular DNA sequence lying next to the DRB1*1501 variant, in effect switching the gene on.
"In people with the DRB1 variant associated with MS, it seems that vitamin D may play a critical role. If too little of the vitamin is available, the gene may not function properly.
“We have known for a long time that genes and environment determine MS risk. Here we show that the main environmental risk candidate – vitamin D – and the main gene region are directly linked and interact,” the researchers explained.
They believe that vitamin D deficiency in mothers or even in a previous generation may lead to altered expression of DRB1*1501 in offspring.
The researchers from the University of Oxford and the University of British Columbia suggested that this gene-environment interaction may affect the ability of the thymus, a key component of the immune system, to perform its regular tasks.
"Our study implies that taking vitamin D supplements during pregnancy and the early years may reduce the risk of a child developing MS in later life. Vitamin D is a safe and relatively cheap supplement with substantial potential health benefits. There is accumulating evidence that it can reduce the risk of developing cancer and offer protection from other autoimmune diseases,” they added.
Details of these findings are published in the journal, PloS Genetics.