Patients with bowel cancer with high levels of vitamin D in their body are more likely to survive the disease, Scottish research suggests.
An Edinburgh University team found that patients with the highest levels of vitamin D in their blood had half the risk of dying from the disease compared to those with the lowest levels of the vitamin over the study period of almost nine years.
The researchers now plan to test whether taking vitamin D tablets during treatment for bowel cancer could increase patients’ chances of survival.
Vitamin D is often called the “sunshine vitamin” as most of it comes from skin exposure to the sun. It can also be obtained to a lesser extent in the diet, from foods such as oily fish and eggs.
In recent years, a growing amount of research has linked vitamin D with a potentially decreased risk of a number of illnesses, including multiple sclerosis and heart disease. But the new study, published in the Journal of Clinical Oncology, is the first to correlate blood levels of vitamin D in bowel cancer patients after their diagnosis with their long-term survival prospects.
The researchers tested blood samples from almost 1,600 patients after surgery for bowel cancer.
The greatest benefit of vitamin D was seen in patients with “stage two” cancer, at which the tumour may be quite large but the cancer has not yet spread.
The researchers said the results showed vitamin D was associated with a much better chance of cancer survival, although the nature of this relationship was not clear.
They are now aiming to set up a clinical trial to test whether taking vitamin D tablets in combination with chemotherapy can improve bowel cancer survival rates.
Professor Malcolm Dunlop, from the Medical Research Council human genetics unit at Edinburgh University, said: “Our findings are promising but it is important to note that this is an observational study.
“We need carefully designed, randomised clinical trials before we can confirm whether taking vitamin D supplements offers any survival benefit for bowel cancer patients.”
Death rates from bowel cancer are slightly higher in Scotland than in the rest of the UK, at 18.7 deaths per 100,000 of the population compared with a UK rate of 16.
In the past, low levels of vitamin D in the Scottish population, caused by a lack of sunshine, have been potentially linked to higher levels of illnesses such as MS.
But researcher Dr Evropi Theodoratou said their study was not able to determine whether this could also be linked to poorer survival from bowel cancer in Scotland.
“These types of studies provide only circumstantial evidence and we need well-designed and adequately powered trials before we can conclude that vitamin D offers survival benefit to colorectal cancer patients,” she said.