NEW YORK — The amount of calcium and vitamin
D in the diet appears to have little or no impact on the risk of
prostate cancer, but the consumption of low-fat or nonfat milk
may increase the risk of the malignancy, according to the
results of two studies published in the American Journal of
Epidemiology.
Dietary calcium and dairy products have been
thought to increase the risk of prostate cancer by affecting
vitamin D metabolism. Data from several prospective studies have
supported an association, but many other studies have failed to
establish a link.
To explore this topic further, Dr. Song-Yi
Park, from the University of Hawaii in Honolulu, and colleagues,
analyzed data from subjects enrolled in the Multiethnic Cohort
Study. This study, conducted between 1993 and 2002, included
adults between 45 and 75 years old, were primarily from five
different ethnic or racial groups, and lived in California or
Hawaii.
A total of 82,483 men from the study
completed a quantitative food frequency questionnaire and
various factors, such as weight, smoking status, and education
levels were also noted, Park’s group said.
During an average follow-up period of eight
years, 4,404 men developed prostate cancer. There was no
evidence that calcium or vitamin D from any source increased the
risk of prostate cancer. This held true across all racial and
ethnic groups.
In an overall analysis of food groups, the
consumption of dairy products and milk were not associated with
prostate cancer risk, the authors found. Further analysis,
however, suggested that low-fat or nonfat milk did increase the
risk of localized tumors or non-aggressive tumors, while whole
milk decreased this risk.
Dr. Yikyung Park, from the National Cancer
Institute at National Institutes (NIH) of Health in Bethesda,
Maryland, and colleagues investigated the relationship of
calcium and vitamin D and prostate cancer in 293,888 men
enrolled in the NIH-American Association of Retired Persons Diet
and Health Study, conducted between 1995 and 2001 in a similar
analysis. The average follow-up period was six years.
No link between total or supplemental dietary
calcium and the total number of non-advanced prostate cancer
cases was noted. Total calcium intake was tied to advanced and
fatal disease, but both associations fell short of statistical
significance.
Similar to the first study’s findings, skim
milk was linked with advanced prostate cancer. Calcium from
non-dairy food, by contrast, was tied to a reduced risk of
non-advanced prostate cancer.
"Our findings do not provide strong support for the
hypothesis that calcium and dairy foods increase the risk of
prostate cancer. The results from other large...studies, with
adequate numbers of advanced and fatal prostate cancers, may
shed further light on this question," Park’s team concludes. –
Reuters
