A team of scientists from Canada and Britain say the sunshine vitamin influences more than 200 genes. That discovery includes genes related to cancer and autoimmune diseases such as multiple sclerosis.
This newest research is in the journal Genome Research.
Most vitamin D is made by the body as a natural byproduct of the skin's exposure to sunlight.
Researchers say vitamin D deficiency is getting worse as people spend more time indoors.
Vitamin D can be taken as a supplement and can also be found in fatty fish such as salmon, herring and mackerel.