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Calcium is the most abundant mineral in the human body. Approximately 98 percent of the estimated 1,000 grams of calcium in the body can be found in bone, 1 percent in teeth, and the remaining amount in the blood and other fluids.
Calcium is the primary component of bone, but even the small amount in the bloodstream is critical for proper heart function, nerve conduction, muscle contractions, blood clotting, and muscle tone. Studies also show that calcium may play a role in reducing the risk of colon cancer and lowering blood pressure.
For about a decade, a growing number of studies have shown a relationship between consumption of dairy foods and/or calcium and the development of prostate cancer. In 2001, for example, the Harvard School of Public Health published the results of a study in which the researchers had followed 20,885 US physicians for 11 years. (Chan 2001) During that time, 1,012 men developed prostate cancer. When the investigators looked at how much calcium in the form of dairy products the men normally consumed, they found that those who averaged more than 600 mg calcium daily had a 32 percent higher risk of prostate cancer than those who regularly consumed 150 mg or less. The American Cancer Society notes that there is evidence that high intake of calcium, mainly through supplements, has been linked with a greater risk of prostate cancer, especially aggressive cancer.
More recent studies have continued to see a link between calcium supplement intake and an increased risk of prostate cancer. In a study conducted by Gary G. Schwartz, PhD, from Wake Forest University Baptist Medical, and Halcyon G. Skinner, PhD, MPH, of the University of Wisconsin, it was reported that men who had high-normal levels of serum calcium (calcium in their blood) at a nearly threefold increased risk for developing fatal prostate cancer when they were compared with men who had a lower average calcium level (calcium with the normal range).
To arrive at this conclusion, the authors evaluated data from the first NHANES survey (National Health and Nutritional Examination Survey, NHANES I) and from a follow-up NHANES conducted years later. The data was gathered from 2,814 men who had their serum calcium levels recorded an average of ten years before some of the men developed prostate cancer. In the follow-up survey, the investigators found 85 cases of prostate cancer, which included 25 deaths from the disease. They also found that the men who had the highest calcium levels were more likely to die of the disease than men who had the lowest levels. (Schwartz 2008)
Schwartz and Skinner conducted several follow-up studies that reaffirmed their original findings and also considered the role of parathyroid hormone (PTH). In the November 2009 issue of Cancer Epidemiology, Biomarkers & Prevention, they reported that their “findings support the hypothesis that serum calcium and serum PTH stimulate prostate growth in men without clinical prostate cancer.” (Skinner 2008) In Future Oncology, Schwartz authored another article entitled “Is serum calcium a biomarker of fatal prostate cancer,” and noted that “Increases in extracellular serum calcium causes a decrease in apoptosis [cell death] and an increase in proliferation and migration of metastatic prostate cancer cells. Thus high levels of calcium in serum may promote the growth of potentially fatal cancer.” (Skinner 2009)
In a more recent study published in the March 2010 issue of Prostate, researchers found a twofold increased risk of prostate cancer associated with an increased intake of dairy products. The investigators analyzed data from 197 men who had prostate cancer and an equal number of controls, all of whom answered questions about their consumption of more than 200 different foods. Of all the dairy foods the men ate, milk was the only one significantly associated with an increased risk of prostate cancer. Among the foods associated with a decreased risk of prostate cancer were legumes, fish, nuts, and vitamin E. (Raimondi 2010)
Results from the European Prospective Investigation into Cancer and Nutrition (EPIC) study provide the most recent findings. EPIC is being conducted in 10 European countries and is studying the dietary factors associated with various types of cancer. The study population includes 519,978 participants (366,521 women and 153,457 men), most of whom are 35 to 70 years old. In the September 2010 issue of the European Journal of Cancer, investigators reported on their findings to date. Regarding prostate cancer, they noted that a high intake of dairy protein and calcium from dairy products was associated with an increased risk of prostate cancer. (Gonzalez 2010)
The bottom line when it comes to calcium and prostate health is that men who consume high amounts of calcium and/or dairy foods are at an increased risk of prostate cancer. Because some calcium is necessary for bone and overall health, the wise approach is to get enough calcium—but not too much—and to get it primarily from foods, not supplements. The recommended intake of calcium is 1,200 mg daily.
See also
Calcium Increases Prostate Cancer Risk in African American Men
Calcium, Dairy and Prostate Cancer Risk
References
Chan JM et al. Dairy products, calcium, and prostate cancer risk in the Physicians’ Health Study. Am J Clin Nutr 2001 Oct; 74(4): 549-54.
Gonzalez CA, Riboli E. Diet and cancer prevention: contributions from the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Eur J Cancer 2010 Sep; 46(14): 2555-62
Raimondi S et al. Diet and prostate cancer risk with specific focus on dairy products and dietary calcium: a case-control study. Prostate 2010 Mar 15
Schwartz GG. Is serum calcium a biomarker of fatal prostate cancer? Future Oncology 2009 Jun; 5(5): 577-80
Skinner HG, Schwartz GG. The relation of serum parathyroid hormone and serum calcium to serum levels of prostate-specific antigen: a population-based study. Cancer Epidemiol Biomarkers Prev 2009 Nov; 18(11): 2869-73
Skinner HG, Schwartz GG. Serum calcium and incident and fatal prostate cancer in the National Health and Nutrition Examination Survey. Cancer Epidemiol Biomarkers Prev 2008 Sep; 17(9): 2302-5
