Getting more vitamin D could reduce the risk dying from cancer, research has suggested.
Experts said that doctors should prescribe time outdoors or a daily pill.
The main source of vitamin D is sunlight, and some foods, including oily fish such as salmon, sardines and mackerel as well as red meat and eggs.
But a shocking 75% of Brits are lacking in the vitamin.
The medics examined ten clinical trials of 79,000 people with an average age of 68 for at least four years.
Those given vitamin D tablets instead of a placebos were 13% less likely to develop cancer and die from it.
During autumn and winter Brits are advised to take a supplement containing 10 micrograms of vitamin D.
Lead researcher Tarek Haykal, of Michigan State University, said: “I would like to see more oncologists and primary care doctors consider prescribing vitamin D for their patients as it carries many benefits with minimal side-effects.”
Dr Rachel Shaw, of Cancer Research UK, said: “Vitamin D may improve prognosis when cancer develops.
“More research is required. It’s important that cancer patients consult their doctor before taking vitamin supplements.”
