HOW TO PREVENT CANCERS

As is clear from a number of our recent posts, there's some long-brewing controversy in academic and public health circles about the potential benefits and risks of raising the recommended daily amounts of vitamin D.  One main camp believes that there is pretty solid evidence that daily vitamin D intakes of 1000 - 2000 IU could have significant health benefits - lowering the risk of osteoporosis, heart disease, cancer, even early death.  The other main camp believes that the current evidence only backs bone-health benefits, which come at lower daily amounts of vitamin D, and that other benefits have yet to be demonstrated.

Despite all its good press of late, vitamin D's health benefits have been challenged recently, most notably in an Institute of Medicine (IOM) report at the tail end of 2010 and in a Perspective piece in the New England Journal of Medicine yesterday (link).  That the two papers have similar conclusions - vitamin D has bone health benefits but no demonstrated benefits for chronic diseases like heart disease and cancer - isn't too surprising.  The latest Perspective paper was written by three of the committee members on the earlier IOM report.

In our response to that IOM paper we wrote that:

The IOM report takes a typically conservative approach to assessing studies of potential benefits and potential risks related to vitamin D intake, as well as to the blood levels of vitamin D that qualify as “sufficient.” Such an approach often minimizes potential benefits while highlighting potential risks.  This can help safeguard the nation’s health from the zeitgeist of diet crazes, but when it comes to vitamin D it seems more like a missed opportunity. (Are the New Recommendations on Vitamin D a Missed Opportunity?) 

In a nutshell, this captures our thoughts on the Perspective paper as well, which focuses on the potential links between vitamin D and cancer risk.

Looking at colon cancer alone, there is good evidence that people with higher circulating vitamin D levels can have as little as half the risk of developing colon cancer as those with lower vitamin D levels (International Agency for Research on Cancer 2008).

For a supplement that has a lot of potential benefit and little risk at levels that could bring this benefit, do we really need to wait 5 or more years until more definitive data might be available?

Related CNiC Posts
Are the New Recommendations on Vitamin D a Missed Opportunity?

Vitamin D and cancer - update

References Cited
International Agency for Research on Cancer (2008). Vitamin D and Cancer. Lyon, International Agency for Research on Cancer.

In the news last month were details of a large Harvard-based randomized clinical trial that will be testing the potential of vitamin D and fish oil supplements to prevent cancer and heart disease (study site). Called the VITAL study -- from the somewhat forced “VITamin D and OmegA-3 TriaL” – the study plans to recruit 20,000 older men and women beginning January 2010 to be in one of four study groups. One group will take both a vitamin D supplement (2,000 IU) and an omega-3 supplement (1g) each day. One group will take placebos of both each day. And the other two groups will take a combination of supplements and placebos.

Vitamin D has certainly been in the news a great deal over the last couple of years for its possible disease prevention qualities. And while the evidence for benefit has been compelling, most of it has come from observational studies. The VITAL study, and other similar planned trials, should help offer some more definitive information about vitamin D’s benefits, and any risks.

Vitamin D article by the prevention team in Woman & Cancer Magazine: Shedding Light on Vitamin D and Cancer by Graham Colditz, MD, DrPH and Hank Dart, SM