Two or More Daily Glasses of Milk May Raise Ovarian Cancer Risks
May 5, 2000 (Boston) -- A milk mustache may not be the most appropriate
fashion statement for women concerned about their health, say scientists from
Harvard Medical School. The latest finding from an ongoing study of more than
80,000 nurses suggests that women who drink two or more glasses of milk a day
have a 44% higher risk of getting ovarian cancer than women who rarely drink
Switching to low-fat or skim milk may not help, says Kathleen M. Fairfield,
MD. Most of the milk drinkers in the nurses' study drank skim or low-fat milk.
While chugging milk increases the overall risk of getting any type of ovarian
cancer by 44%, it increases the risk for the most common type of ovarian cancer
-- called serous tumors -- by 66%, Fairfield says. Ovarian cancer, she says, is
the fifth most common cancer among American women.
Fairfield suggests that neither the fat nor the calcium content of milk
increases the risk. Lactose, or milk sugar, appears to be the most likely
culprit. Every 8-ounce glass of milk -- any type of milk--- contains about 11
grams of lactose.
In the body, lactose is broken down into two simple sugars -- glucose and
galactose. In this case, Fairfield says that she and her colleagues think it
may be the galactose that is in some way linked to cancer growth. That means
lactose-free milk wouldn't be a good substitute because it contains galactose,
Currently, women are advised to increase their consumption of dairy products
to protect against osteoporosis, and Fairfield says those "osteoporosis
recommendations are at just about the same consumption level that we are
associating with ovarian cancer." What's a woman to do?
Because these results have not yet been reviewed by other scientists or
published, Fairfield tells WebMD she is reluctant to make any recommendations.
When asked by another physician how she would advise a 45-year-old female
patient, Fairfield says she won't tell women who drink milk to stop. "But
if a woman is concerned about osteoporosis but isn't currently a milk drinker,
I am going to start her on calcium supplements."
The study involves 80,326 married nurses living in 11 states. When the
nurses entered the study in 1976, they ranged in age from 30 to 55. Beginning
in 1980, all participants were given detailed dietary questionnaires. Fairfield
and her co-authors reported on 16 years of dietary studies. The women were
asked about dairy product consumption and other sources of calcium.
"There were 301 cases of ovarian cancer diagnosed during the study
period; 174 were serous tumors," she says.
"We found that women were getting 57% of their dietary lactose from
low-fat or skim milk, 15% from whole milk, and 8% from yogurt," she says.
Fairfield says cheese doesn't contain high amounts of lactose. And "whole
milk accounts for only 15% of lactose because so little whole milk is