Increased blood levels of vitamin D may reduce the risk of colorectal cancer by 40 percent, says a study.
Using data from over half a million participants of the European Prospective Investigation into Cancer Study (EPIC) involving 10 European countries, the researchers analyzed dietary and lifestyle information obtained from questionnaires, and collected blood samples (1). The data showed that blood levels of vitamin D below a mid-level of 50 to 75 nanomoles per liter were associated with an increased risk of colorectal cancer, while blood levels above this were not associated with any additional benefits.
Additionally, higher consumption of dietary calcium, but not dietary vitamin D, was found to be associated with a reduced risk of colorectal cancer.
The potential benefits for the vitamin, alone or in combination with calcium, for colorectal health are somewhat controversial, with some studies reporting benefits while others report no results. Indeed, back in 2006 results from the Women's Health Initiative (WHI) stated that daily supplements of vitamin D and calcium 'had no effect' on the risk of colorectal cancer. The results were questioned however and independent cancer experts said at the time that the study had a complex design with potential confounders.
Colorectal cancer accounts for nine percent of new cancer cases every year worldwide. The highest incidence rates are in the developed world, while Asia and Africa have the lowest incidence rates. It remains one of the most curable cancers if diagnosis is made early.