Higher levels of vitamin D leads to lower cancer risk

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CANCER DIGEST – April 7, 2016 – Researchers at University of California, San Diego School of Medicine report that the higher the levels of a marker for vitamin D in the blood, the lower the risk of cancer. The findings are published in the April 6, online issue of the journal PLOS ONE.

The new  study aimed to determine what level of 25-hydroxyvitamin D in the blood was required to effectively reduce cancer risk. 25-hydroxyvitamin D is the main form of vitamin D in the blood. Vitamin D has been linked to lower risk of cancer since the 1980s, but what the level needs to be to provide the protection has been controversial.

The researchers employed a non-traditional approach, pooling analyses of two previous studies of different types: a randomized clinical trial of 1,169 women and a prospective cohort study of 1,135 women. A clinical trial focuses upon whether a specific test or treatment is safe and effective. A prospective study looks for outcomes during the study period, in this case incidence of cancer among participants. By combining the two studies, the researchers obtained a larger sample size and a greater range of blood serum levels of 25-hydroxyvitamin D or 25(OH)D.

They found that women with 25(OH)D concentrations of 40 ng/ml or greater had a 67 percent lower risk of cancer than women with levels of 20 ng/ml or less. The age-adjusted cancer incidence was 1,020 cases per 100,000 person-years in the Lappe cohort and 722 per 100,000 person-years in the GrassrootsHealth cohort. Cancer incidence declined with increased 25(OH)D. 

Many vitamin D supporters currently advocate 800 to 1,000 IUs daily; more for persons older than 70 and pregnant or lactating women.