BOSTON, MASSACHUSETTS. Several studies have found that a high intake of calcium from dairy products increases the risk of prostate cancer. Other studies have found no such correlation. Now researchers at the Harvard Medical School weigh in with the results of a major study that confirms the correlation. The study involved 20,885 male American physicians who were enrolled in 1984. During 11 years of follow-up 1012 of the men developed prostate cancer including 411 cases of advanced prostate cancer. The physicians completed food frequency questionnaires to determine their intake of calcium- containing dairy products (whole milk, skim milk, cheese and ice cream). About 57 per cent of the calcium obtained from dairy products originated from skim milk which contains 307 mg of calcium per serving (8 oz glass). A thorough statistical analysis of the data collected showed that men who consumed more than 600 mg/day of calcium (equivalent to two glasses of skim milk) had a 32 per cent greater risk of developing prostate cancer, after adjusting for other potential risk factors, than did men who consumed 150 mg/day of calcium or less.
The researchers believe that a high intake of calcium suppresses the synthesis of 1,25-dihydroxyvitamin D-
3, an important hormone believed to be protective against prostate cancer. They point out that another large
study found that calcium from supplements also increases prostate cancer risk.