A study has linked vitamin D deficiency with an increased risk for cancer and autoimmune diseases like MS, lupus and rheumatoid arthritis (RA).

Vitamin D deficiency is connected with conditions such as rickets, which causes softness or weakening of the bones. However, this recent study by lead author Dr. Sreeram Ramagopalan from the Wellcome Trust Centre for Human Genetics at Oxford University and his colleagues further implicates vitamin D in other serious illnesses.

Vitamin D interacts with our genes through the vitamin D receptor. This receptor binds to the human genome at specific locations and in this way influences how a gene is expressed. In the study, the researchers used DNA sequencing technology to map vitamin D receptor binding throughout the human genome and found more than 2000 places where this binding happened. They discovered that the vitamin D receptor binding is enhanced at specific areas of the human genome that is associated with autoimmune diseases like type I diabetes, MS, RA and Crohn's disease, as well as certain cancers, including leukemia and colorectal cancer. These illnesses are caused by a combination of genetic and environmental factors and vitamin D deficiency appears to be a major environmental factor in increasing the risk of developing such disorders. The study also found sites for vitamin D receptor binding in areas of the genome that contain genetic changes more common in people from Europe and Asia. This offered support for the theory that lighter skin and hair color evolved as populations moved to more northern and less sunny areas in order to maximize vitamin D absorption from the sun.

What does this mean in a practical sense? Dr. Ramagopalan is quoted as saying ‘There is now evidence supporting a role for vitamin D in susceptibility to a host of diseases. Vitamin D supplements during pregnancy and the early years could have a beneficial effect on a child's health in later life." Some countries (e.g., France) have started public health measures to help protect pregnant women and small children against vitamin D deficiency.

How to Assess Your Vitamin D Level and Increase Your Levels

It is estimated that 1 billion people worldwide do not get enough vitamin D. In the US, as many as 70% of children and adults are D deficient. The cause of this is a combination of not enough sun exposure and a diet low in vitamin D. Certain medications may also impact vitamin D absorption and kidney and liver disease can also lead to vitamin D deficiency.

Finding out whether your vitamin D levels are low is a matter of a simple blood test called the 25-hydroxy vitamin D test. Access to getting the test may become an issue, though. Due to vitamin D deficiency increasingly being implicated in many health conditions and the subsequent popularity of the test, Medicare has proposed vitamin D testing restrictions. In the Canadian province of Ontario, the provincial public health insurance OHIPdecided in late 2010 to only cover the cost (about $50) for a small number of medical disorders.