Those with the highest levels have half the risk of dying from the cancer compared to those with the lowest levels of the vitamin, a new study has found.
Researchers from the University of Edinburgh tested blood samples of nearly 1,600 bowel cancer patients after surgery.
The greatest benefit was seen in those with stage 2 cancer, where the tumour was growing but hadn't spread.
Three-quarters of the patients with the highest levels of the vitamin were still alive five years later, compared with just two-thirds of those with the lowest levels.
Now the researchers want to give cancer patients vitamin D supplements to see if it will help keep them alive.
(Source: University of Edinburgh)