High vitamin D levels linked with decreased risk of colorectal cancer

As many as 3 in every 100 of the population of Europe will develop colorectal cancer during their lifetime, and much work is being done around the world to establish not only risk factors, but also protective factors for this disease.

Initial laboratory work had suggested that vitamin D may prevent the growth of colorectal cancers. However, epidemiological studies did not support this finding. These studies used questionnaires to estimate dietary intake of vitamin D.


A new study published in the BMJ now seems to confirm the link between high levels of vitamin D and a decreased risk of developing colorectal cancer. This was a large study, involving participants from 10 European countries and led by Professor Elio Riboli of Imperial College, London. He used the European Prospective Investigation into Cancer (EPIC) study to gather his data, which was based on detailed questionnaires and blood sampling.


The results released suggest that the individuals with the highest levels of vitamin D had a 40% lower risk of developing colon cancer. The results did not suggest a similar link with rectal cancer.


Interestingly, the link with vitamin D levels was not mirrored in individuals with a high intake of dietary vitamin D. Vitamin D comes both from the diet and from skin exposure to sunlight. Researchers now suggest that it may be the vitamin D from sunlight exposure that is providing this protective effect, although stress that excessive sun exposure can damage the skin and cause skin cancer.


It is not yet known whether the relationship between vitamin D levels and colon cancer is directly protective, and it is not known whether increased vitamin D in the diet confers these apparent effects.