Vitamin D, believed to be useful to protect against cancer by
many people, may not be a strong anti-cancer agent except for colon
cancer, according to a new study published in the Journal of the
National Cancer Institute in Bethesda, Maryland.
"Over the past several years, a number of publications have
suggested that vitamin D can reduce deaths from various forms of
cancer," said Dr. Len Lichtenfeld, deputy chief medical officer of
the American Cancer Society. "This is a further bit of evidence
that leads us to call for further investigations before we make
recommendations for the general population."
Dr. D. Michal Freedman, from the National Cancer Institute in
Bethesda, Maryland, and his colleagues analyzed data from the third
national Health and Nutrition Examination Survey to examine the
relationship between levels of circulating vitamin D in the blood
and cancer mortality in a group of 16,818 participants aged 17 and
older.
After about a decade of follow-up, 536 participants had died of
cancer. Cancer mortality was not related to the level of
circulating vitamin D for the overall group, nor was it related
when the researchers looked at the data by sex, race, or age.
The only possible exception is that high blood levels of vitamin
D do seem to correlate with a reduced risk of death from colon
cancer.
An editorial published with the study, written by experts
including Johanna Dyer, DSc, RD, of the Office of Dietary
Supplements at the National Institutes of Health, 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."
(Agencies via Xinhua News Agency October 31, 2007)