Cancer risk falls with higher levels of vitamin D

In the journal PLOS One, researchers from the University of California-San Diego (UCSD) School of Medicine report how they analyzed the link between vitamin D and cancer to determine what blood level of vitamin D was required to effectively reduce cancer risk.

The study included all invasive cancers, excluding skin cancer.

One of the authors, Cedric Garland, adjunct professor in the UCSD School of Medicine Department of Family Medicine and Public Health, says their study is the first to put numbers on this relationship, as he explains

"We have quantitated the ability of adequate amounts of vitamin D to prevent all types of invasive cancer combined, which had been terra incognita until publication of this paper."

Vitamin D, which is produced by the body through exposure to sunshine, helps the body control calcium and phosphate levels. It was Prof. Garland and his late brother Frank who first linked low vitamin D with cancer in the 1980s. They found people who lived at higher latitudes and thus had less access to sunlight had lower levels of vitamin D and were more likely to develop bowel cancer. Since then, further studies by the Garland brothers and others have found links between low vitamin D and other cancers, including cancers of the breast, lung and bladder.

Much debate about recommended level of vitamin D. The only accurate way to measure vitamin D in the body is to measure the level of 25-hydroxyvitamin D in the blood. The kidneys convert 25-hydroxyvitamin D into the active form that helps control calcium and phosphate levels.

There has been much debate in recent years about what the recommended blood levels of vitamin D should be. In 2010, the Institute of Medicine (IOM) recommended a target of 20 ng/ml for bone health, which could be met in most healthy adults (aged 19-70), with the equivalent of 600 IU of vitamin D each day.

Since then, other groups have argued that the target level should be higher, at 50 ng/ml or more.

In the new study, Prof. Garland and colleagues wanted to find out what blood level of vitamin D effectively reduces cancer risk.

They took an approach that is not normally used. They used the results from two different types of study: one a clinical trial of 1,169 women and the other a prospective study of 1,135 women. For some of their analysis, they kept the two data sets separate and compared them, and in another part, they pooled the data to create a larger sample.

source:medical new stoday