Evidence indicates that excessive calcium intake may increase the risk of developing metastatic prostate cancer (advanced prostate cancer). A 1998 Harvard School of Public Health study of 47,781 men found those consuming between 1,500 and 1,999 mg of calcium per day had about double the risk of being diagnosed with metastatic prostate cancer as those getting 500 mg per day or less. Men taking in 2,000 mg or more had over four times the risk of developing metastatic prostate cancer as those taking in less than 500 mg.
Harvard researchers performed a follow up study of dairy product intake in 1,062 men. The study found a 50% increase in prostate cancer risk and a near doubling of risk of metastatic prostate cancer among men consuming high amounts of dairy products, likely due, say the researchers, to the high total amount of calcium in such a diet.
An even more recent study at Harvard that was published in October 2001 looked at dairy product intake among 20,885 men and found men consuming the most dairy products had about 32% higher risk of developing prostate cancer.
As is usual with prostate cancer we are again faced confusion. Clearly, excess calcium intake is linked to prostate cancer risk. However, calcium also has the ability to help prevent osteoporosis (weakening of the bones usually associated with aging), and possibly to lower risk of colon cancer. Those of us who are on a hormone blockade accelerate the bone loss process, which means we are even more susceptible to breaking our bones and to having jaw infections.
To add an additional wrinkle, the more calcium a person takes in through diet, the less the body produces of a kind of vitamin D — calcitriol — which has been shown to reduce replication of prostate cancer cells.
For people who do not have prostate cancer, on balance, moderation is probably the best strategy. Personally, I believe that if you have prostate cancer, the best route is to avoid calcium supplements and diary products. Small amounts of goat or sheep cheese can serve as an alternative to cow cheese. Also, you should consider adding calcitriol to your schedule of supplements.
You can read additional information about the effects of calcium supplements at:
Joel T Nowak MA, MSW