New research has been released showing that a large daily dose of vitamin D can dramatically lower the risk of people developing common cancers. The findings have been given a cautious welcome by cancer charities. US researchers found the "natural" form of the vitamin, known as D3, could dramatically reduce the chances of developing breast, ovarian and colon cancer, as well as others.

But Cancer Research UK said the evidence is "complex and confusing". "There is evidence to suggest that the vitamin plays a role in keeping cells healthy," spokeswoman Sara Hiom said.

"But further research is needed to understand what role vitamin D may play in preventing cancer in humans."

The study concluded that taking 1,000 international units (IU) of the vitamin daily could lower an individual's cancer risk by half.

D3 is normally produced in the skin by the action of sunlight but is also obtained from certain foods.

Dietary sources are limited, however. A glass of milk, for instance, contains only 100 IU of the vitamin.

The research was published in the American Journal of Public Health after case studies going back 25 years.