UK researchers found that vitamin D levels affect the expression of genes relating to a range of diseases.

What did the study examine?
Researchers from the University of Oxford studied the effect of vitamin D on human gene expression.

They identified 2,276 sites on the genome where the vitamin could bind to DNA. These binding sites were grouped around genes which have been linked to MS, Crohn's disease, lupus and arthritis, as well as leukaemia and colorectal cancers.

The researchers also found 229 genes showing significant changes in expression in the presence of vitamin D. Among these were two genes that have been implicated in Crohn's disease and type-1 diabetes.

What are the implications?
Vitamin D deficiency has already been strongly linked with MS, arthritis and type-1 diabetes.

But the researchers believe the findings could help scientists understand the mechanisms underlying this connection.

The study has also strengthened the evidence for links between vitamin D deficiency and other diseases, they said.

Dr Sreeram Ramagopalan, the lead author of the research, pointed out that the study had only looked at gene expression in cells grown in the lab.

'There's nothing directly medically useful at present,' he said.

Hazel Nunn, health information manager at Cancer Research UK, said that clinical trials would still be needed to know whether boosting levels of vitamin D could help to prevent these conditions.

Can deficiency be reduced?
Dr Ramagopalan thinks that vitamin D deficiency could be tackled in two ways.

'Guidance on sun exposure needs to be updated,' he said. 'In Britain there are four to six months a year where we don't get the UV rays necessary for vitamin D production. Spending 10 minutes in the sun before putting on sun cream would help.'

He said that fortifying more foods with vitamin D could also reduce deficiency.

• Genomees Online 2010

Informing patients
Vitamin D alters the expression of genes related to a number of diseases, including cancer. Low levels of vitamin D may increase the risk of developing these diseases, but more research is needed. Enjoying the sun safely is the best way to get enough vitamin D, but oily fish and eggs are also good natural sources of vitamin D.