Vitamin D May Not Cut Cancer Deaths
Study Shows No Link Between Vitamin D Level and Cancer Deaths -- Except for Colorectal Cancer
Oct. 30, 2007 -- Cancer researchers today reported that blood levels of vitamin D --
whether high or low -- may not help prevent adults from dying of cancer over a
But colorectal cancer may be the exception, according to the scientists, who
included D. Michal Freedman,
PhD, MPH, of the National Cancer Institute.
Vitamin D has attracted attention from researchers for its possible
Freedman's team studied data on more than 16,800 people aged 17 and older
who participated in U.S. health studies between 1988 and 1994.
In those studies, participants got a blood test to measure their blood level
of vitamin D.
Freedman and colleagues followed the participants through 2000. During those
12 years, 536 participants died of cancer.
Participants' vitamin D levels at the study's start didn't appear to affect
cancer mortality in general, regardless of age, sex, race, or other
However, people with high levels of vitamin D at the study's start were 72%
less likely than those with low levels of vitamin D to die of colorectal
Death rates for the other cancers that were studied, including lung cancer,
breast cancer, prostate cancer, other digestive cancers, non-Hodgkin's
lymphoma, and leukemia, weren't linked to vitamin D blood levels.
The study's limits include the fact that participants only had their vitamin
D level checked once. So it's not clear if their vitamin D level rose or fell
over the years.
Freedman's team had lots of data including which participants smoked and
exercised. But they can't rule out the possible influence of other factors.
The study appears in next week's edition of the Journal of the National
An editorial published with the study states that "the relationship
between nutritional factors and colorectal as well as other cancers is
complicated" and that the findings "must be put into the context of
total diet and lifestyle."
The editorial was written by experts including Johanna Dyer, DSc, RD, of the
Office of Dietary Supplements at the National Institutes of Health (NIH).