Among Chinese men, calcium consumption -- even at relatively low levels and from non-dairy food sources such as soy, grains and green vegetables -- may increase prostate cancer risk, according to results published in Cancer Research, a journal of the American Association for Cancer Research.
"Our results support the notion that calcium plays a risk in enhancing the role of prostate cancer development," said lead researcher Lesley M. Butler, Ph.D., assistant professor of epidemiology at Colorado State University, Fort Collins, Colo. "This study is the first to report an association at such low levels and among primarily non-dairy foods."
Some studies conducted in North American and European populations have linked high consumption of dairy products to an increased risk of prostate cancer. A few studies have suggested that calcium in milk is the causative factor, however the evidence is not clear.
In an Asian diet, non-dairy foods like tofu, grains and vegetables such as broccoli, kale and bok choy are the major contributors of calcium intake. Therefore, Butler and colleagues speculated that people who are exposed to those calcium-rich food sources in an Asian diet may also be at increased risk for prostate cancer.
Using data from the Singapore Chinese Health Study, the researchers evaluated whether dietary calcium increased prostate cancer risk in a population of 27,293 Chinese men aged 45 to 74 years, with low dairy consumption. The study was restricted to men who belonged to two major dialect groups of Chinese people living in Singapore: the Hokkiens and the Cantonese.
The Singapore Chinese Health Study, funded by the U.S. National Institutes of Health, National Cancer Institute, is a population-based prospective study initiated between 1993 and 1998.