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Calcium
voor minder kanker.*
Vrouwen
die per dag meer dan 800 mg calcium “eten” hebben wel 26% minder kans op
darmkanker.
Als
je die calcium ook nog eens haalt uit zowel voeding als supplementen dan
vermindert die kans wel tot 46%. Dit blijkt uit een grootschalige studie over
meer dan 10 jaar in Amerika. Uit eerdere studies is al gebleken dat deze
resultaten ook voor mannen gelden, met de opmerking dat mannen moeten oppassen
met melkprodukten omdat die meer risico op prostaatkanker kunnen geven.
Calcium
May Protect Women From Cancer
A
University of Minnesota Cancer Center study found that women consuming more than
800 milligrams of calcium each day reduced their risk of colorectal cancer by as
much as 26 to 46 percent. A 26 percent reduction in risk of colorectal cancer
occurred regardless of whether the calcium intake was from diet or supplement.
Among women who consumed high levels of calcium from both diet and supplements,
the risk reduction was almost double that observed for calcium from either
source by itself. The results of the study appear in this month's Cancer
Epidemiology, Biomarkers and Prevention journal. Andrew Flood, Ph.D.,
epidemiologist with the University of Minnesota Cancer Center and School of
Public Health, led the study in collaboration with the National Cancer Institute
(NCI).
The
study involved 45,354 women in the United States who did not have a history of
colorectal cancer. The women were categorized into groups according to
information they provided about their diets and lifestyles. The women averaged
61.9 years of age upon entering the study and they were followed in the study
for an average of 8.5 years. This study began in 1987 and closed in 1997. During
that time, 482 women in the study developed colorectal cancer.
"It
is especially notable that the risk reduction was present regardless of the
source of the calcium, and that simultaneously consuming high levels of calcium
from both diet and supplements further reduced risk," Flood said.
"These observations suggest that it was the calcium per se, and not merely
dairy products or some other variable that accounted for the reduction in
risk."
The
findings provide further evidence in a growing body of research that indicates a
link between calcium and prevention of colorectal cancer. This study is good
news for women because they comprise about half of the approximately 150,000
people in the United States diagnosed annually with colorectal cancer. The
cancer ranks as the second leading cause of cancer death, and the risk of
contracting it increases with age.
Flood
notes that more research needs to be done to understand why and how calcium
provides protection against colorectal cancer in some women.
"We
really don't know at this point," Flood said. "There are currently two
main theories. One is that calcium has the ability to neutralize secondary bile
acids that are produced during the digestion of fat and are highly irritating to
the cells in the lining of the colon. The evidence in support of this theory is
not very strong.
"An
alternate theory is that calcium has a direct impact on a whole series of
biochemical pathways within the cells that line the colon and rectum. These
pathways play important roles in regulating how these cells grow and mature and
thus, can be important components of the cancer process."
To
put the study results in perspective, Flood says consuming a diet rich in
calcium – one that provides at least 800 mg per day, which is actually lower
than the current recommended daily allowance of 1,200 mg per day--is a safe and
effective way for women to help guard themselves against colorectal cancer.
As
for the benefit of calcium for men, he said, "The results of this study are
consistent with other studies that show calcium reduces risk of colorectal
cancer in both women and men. A note of caution for men, however, is that dairy
foods, the primary source of calcium in the U.S. diet, have been linked in some
studies to increased risk of prostate cancer." (Febr. 2005)