Annually, doctors in the U.S. diagnose more than 200,000 prostate cancer cases. According to the National Cancer Institute, more than 32,000 of those men die from the disease. In 2000, Chan and colleagues reported that men with low intakes of calcium developed fewer cases of prostate cancer in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study. The American Institute for Cancer Research independently concluded that limited evidence exists to suggest that milk or dairy products cause prostate cancer. The panel further concluded that diets high in calcium may increase the risk of prostate cancer.
Calcium in Dairy Products
Second to fortified cereals, dairy products including milk, cheese, and yogurt boast the highest dietary calcium sources, according to the United States Department of Agriculture. A breakfast of one cup of milk with a calcium fortified cereal exceeds the dietary reference intake of 1,200mg of calcium per day. In a Finish report by Mitrou and colleagues, researchers found a 26 percent increase in risk of prostate cancer when men consumed 1,000 to 1,499mg of calcium daily compared to men that consumed less than 1,000mg of calcium. The risk of prostate cancer rose with each increase in total calcium intake.
Calcium and Vitamin D
Vitamin D helps to regulate blood calcium levels. Therefore, elevated levels of calcium reduce the formation of active vitamin D. According to a review by Trump and colleagues, vitamin D serum levels impact the growth and differentiation of cancers. Additionally, vitamin D reduces the growth of supporting blood vessel networks to tumors and induces death of the cancer cells. Elevated levels of calcium may inhibit the positive effects of adequate vitamin D levels.
Dairy, Calcium and IGF-1
According to the American Institute for Cancer Research, milk or calcium intake increases serum insulin-like growth factor, IGF-1. IGF-1 affects important regulators of cancer including: cell growth, differentiation and metastasis. A review paper by Lima and colleagues states that the positive association between serum IGF-1 and prostate cancer is well established by the literature. Therefore, milk or calcium increases total IGF-1, which raises the risk of prostate cancer.
Calcium or Dairy
Discerning whether calcium alone or as a component of dairy products is responsible for the increased risk of prostate cancer proves difficult. Green leafy vegetables, soy and some grains contain up to one third of your daily calcium requirement. Green leafy vegetables and soy reduce your risk of developing prostate cancer according to the National Cancer Institute. Future research will determine whether calcium alone is responsible for increasing the risk of prostate cancer or whether calcium is simply a biomarker of dairy intake.
References
- "Cancer Causes Control"; Diet and Prostate Cancer Risk in a Cohort of Smokers, with a Specific Focus on Calcium and Phosphorus (Finland); JM Chan, et al.; Oct. 2000
- "Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective"; American Institute for Cancer Research; 2007
- National Cancer Institute: SEER Stat Fact Sheets: Prostate
- "Cancer Journal"; Vitamin D: considerations in the continued development as an agent for cancer prevention and therapy; DL Trump, et al.; Jan. 2010
- "International Journal of Cancer"; A Prospective Study of Dietary Calcium, Dairy Products, and Prostate Cancer Risk (Finland); PN Mitrou, et al; Jun. 2007
- "Archives of Brazilian Endocrinology and Metabolism"; IGF-1, Insulin, and Prostate Cancer; GA Balarini Lima, et al. Nov. 2009
