By Lindsey Tanner
The Associated Press
Published: February 24, 2009
A study in nearly half a million older men and women bolsters
evidence that diets rich in calcium may help protect against some cancers.
The benefits were mostly associated with foods high in calcium, rather than
calcium tablets.
Previous studies have produced conflicting results. The new research
involved food questionnaires from participants and a follow-up check of
records for cancer cases during the subsequent seven years. This research
method is less rigorous than some previous but smaller studies.
But because of its huge size - 492,810 people and more than 50,000 cancers -
the new study presents powerful evidence favoring the idea that calcium may
somehow keep cells from becoming cancerous, said University of North
Carolina nutrition expert John Anderson, who was not involved in the study.
The study was run jointly by the National Institutes of Health and AARP. The
results appear in Monday's Archives of Internal Medicine.
National Cancer Institute researcher Yikyung Park, the study's lead author,
called the results strong but said more studies are needed to confirm the
findings.
Duke University nutrition researcher Denise Snyder said the results support
the idea that food rather than supplements is the best source for nutrients.
Participants were AARP members aged 50 to 71 who began the study in the
mid-1990s. A total of 36,965 men and 16,605 women were later diagnosed with
cancer. There were more than 10 different kinds of cancer, the most common
being prostate, breast, lung and colorectal.
Compared with people who got little calcium, those who consumed the most had
the lowest chances of getting colon cancer. Those in that highest category
got on average 1,530 milligrams a day among men and 1,881 milligrams daily
among women. The recommended amount for older people is 1,200 milligrams,
and getting much more than that didn't result in any greater protection.
Adults can get that amount from four cups of milk or calcium-fortified
orange juice.
Men who got the most calcium from food were about 30 percent less likely to
get cancer of the esophagus, about 20 percent less likely to get head and
neck cancer and 16 percent less likely to get colon cancer, when compared to
men who got low amounts of calcium.
Among women, those who got the most food-based calcium were 28 percent less
likely to get colon cancer than low-calcium women.
In men, calcium supplements only seemed to help protect against colon
cancer; for women, supplements meant a lower risk for liver cancer, which is
rare.
Some previous studies have linked diets high in calcium with prostate cancer
but the current study found no such risk.
Adults who ate the most calcium also tended to be healthier overall than the
others.
Northwestern University preventive medicine instructor Patricia Sheean
called the results impressive. But she noted that all those in the study,
AARP members, may have been healthier and wealthier than the general U.S.
population so it's not clear if the results would apply to the wider
population.