Lower Vitamin D brings higher colorectal cancer risk

The large group of researchers who completed this study published recently in the British Journal of Medicine set out "To examine the association between pre-diagnostic circulating vitamin D concentration, dietary intake of vitamin D and calcium, and the risk of colorectal cancer in European populations." There were no less than 520,000 participating subjects from 10 countries. The results were clear-cut: "25-(OH)D concentration showed a strong inverse linear dose-response association with risk of colorectal cancer." [25-(OH)D is the active form of vitamin D that we measure with blood tests.] Interestingly, however, they also found that "Dietary vitamin D was not associated with disease risk." What does this mean? It highlights a very important point: it is not possible to judge whether you have enough vitamin D in your system by what you consume. There are marked differences in genetic and conditional need, and the only way to reliably know that you are adequate or optimal for vitamin D is by the blood test. The authors concluded: "The results of this large observational study indicate a strong inverse association between levels of pre-diagnostic 25-(OH)D concentration and risk of colorectal cancer in western European populations." The 'take home' message is that colon cancer is another in the long list of conditions for which vitamin D is important prevention—but you have to test to know where you stand.