BOSTON, MASSACHUSETTS. Several studies have found a link between a high
consumption of milk and cheese and the risk of prostate cancer. Now researchers
at the Harvard Medical School report that men with a high calcium intake have a
higher risk of developing prostate cancer. Their study began in 1986 and
included over 47,000 male health practitioners. The participants completed food
frequency questionnaires in 1986, 1988, 1990, 1992, and 1994. Between 1986 and
1994 a total of 1792 cases of prostate cancer were diagnosed among the men with
423 of the cases being of an advanced nature. After adjusting for other factors
affecting prostate cancer risk the researchers concluded that men with a calcium
intake of 2000 mg/day or more have a 2.97 times higher risk of developing
advanced prostate cancer and a 4.57 times higher risk of developing metastatic
prostate cancer than do men with an intake of 500 mg/day or less. Both calcium
from food and calcium from supplements increased the risk. Milk consumption
increased the risk of prostate cancer significantly with men drinking more than
two glasses per day having a 60 per cent higher risk of advanced prostate cancer
and an 80 per cent higher risk of metastatic prostate cancer than did men who
did not consume milk.
The researchers also found that fructose protects against the development of
prostate cancer. Men who consumed more than 70 grams/day had half the risk of
developing advanced prostate cancer than did men who consumed only 40 grams/day
or less. The main sources of fructose in the study were fruits, carbonated
beverages, and sweet bakery products. A high fruit intake as such was also
found to be protective with men consuming five servings a day having a 37 per
cent lower risk of advanced prostate cancer than men who only consumed one
serving a day or less. The researchers speculate that calcium interferes with
the formation of 1,25-dihydroxycholecalciferol, the biologically active form of
vitamin-D which has been found to suppress the development of prostate tumors.
Somewhat surprisingly, they did not find any relationship between prostate
cancer risk and vitamin-D intake from foods or supplements between the range of
less than 150 IU/day to more than 800 IU/day. They conclude that increased
fruit consumption and avoidance of a high calcium intake by middle-aged and
older men may reduce the risk of prostate cancer.
|