Effect is strongest for women, study finds, doesn't extend to other malignancies
MONDAY, Feb. 23 (HealthDay News) -- High dietary intake of calcium may reduce the incidence of colorectal cancer, especially for women, but has no apparent effect in reducing other malignancies, a U.S. National Cancer Institute study finds.
Why calcium should influence cancer risk differently in women versus men isn't clear, said Yikyung Park, a staff scientist at NCI who led the study. "One can speculate that hormonal or metabolic factors contribute to this difference," she said.
Park and her colleagues relied on data for nearly 500,000 men and women who participated in the U.S. National Institutes of Health-AARP Diet and Health Study. Participants filled out a food questionnaire when they enrolled and then were followed for an average of seven years.
"In both men and women, dairy food and calcium intakes were inversely associated with cancers of the digestive system," the researchers reported in the Feb. 23 issue of the Archives of Internal Medicine.
The top one-fifth of women with the highest intake averaged 1,881 milligrams of calcium per day. This group experienced a 23 percent lower risk of colon cancer than those women in the lowest fifth of intake, who averaged 494 milligrams daily. The comparable reduction for men was 16 percent.
The U.S. Institute of Medicine recommends a daily calcium intake of 1,200 milligrams for adults 50 and older, roughly the amount found in three cups a day of the dairy products that are the main sources of calcium. Other sources of calcium include sardines and green, leafy vegetables.
Calcium has been shown to reduce abnormal growths and induce normal turnover of cells in the gastrointestinal system, the report noted.
The study was done because "calcium has been hypothesized to play different roles in different cancer sites, but testing has been incomplet
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