Does Calcium Intake Promote Prostate Cancer?
In the past, studies carried out in European and North American populations found a high consumption of dairy products being linked to increased risks of developing prostate cancer. Though the evidence is not clear, some studies suggest the calcium in milk being the causative factor. More recently, results published in the American Association for Cancer Research journal, Cancer Research, discovered that even relatively low levels of calcium consumption may increase prostate cancer risk among Chinese men.
The lead researcher of the study was the assistant professor of epidemiology at Colorado State University, Lesley M. Butler, PhD. The results of this study support the concept that calcium does play a role in enhancing the risk of prostate cancer development. However, this study is the first of its kind to report an association at such low levels of calcium consumption, and among primarily non-dairy foods including soy, grains and green vegetables.
Dairy products do not at all account for a large portion of an Asian diet. Therefore, the majority contributions of calcium intake in Asian populations come from non-dairy foods such as tofu, grains and vegetables like broccoli, kale and bok choy. Because of this, people exposed to more of these foods that are sources of calcium in an Asian diet were speculated to be at an increased risk for prostate cancer by Butler and his colleagues. Data from over 27,000 Chinese men between the ages of 45 to 74 living in Singapore from the Singapore Chinese Health Study were used by the researchers to evaluate the association between dietary calcium and prostate cancer risk.
The population-based prospective Singapore Chinese Health Study was funded by the U.S. National Institutes of Health, National Cancer Institute between 1993 and 1998. A total of 298 of these men were diagnosed with incident prostate cancer. Researchers at Colorado State University, the National University of Singapore, along with the University of Minnesota assessed the participants’ baseline diet. According to the results, those who consumed 658 mg vs. 211 mg of total calcium a day showed a 25% increased risk of prostate cancer. Also, since it has been suggested that calcium is absorbed more in smaller individuals, men with lower than average BMI were found to have a twofold increase in prostate cancer risk. Butler states that they are somewhat surprised that their finding was consistent with previous studies even though most of them were done in Western populations with diets high in calcium from dairy sources. This adds more evidence to the growing notion that calcium is a cause of prostate cancer.