Vitamine
D tegen kanker.*
Volgens een Amerikaans onderzoek reduceert voldoende vitamine D de kans op het krijgen van pancreaskanker wel met bijna de helft.
100 gram tonijn geeft al de helft van de benodigde dagelijkse hoeveelheid vitamine D. Een paar keer per week een kwartier buiten zijn in de zon geeft al een voldoende hoeveelheid vitamine D.
Consumption of Vitamin D tablets was found to cut the risk of pancreatic
cancer nearly in half, according to a study led by researchers at Northwestern
and Harvard universities.
The findings point to Vitamin D's potential to prevent the disease, and is one
of the first known studies to use a large-scale epidemiological survey to
examine the relationship between the nutrient and cancer of the pancreas. The
study, led by Halcyon Skinner, Ph.D., of Northwestern, appears in the September
issue of Cancer Epidemiology Biomarkers & Prevention.
The study examined data from two large, long-term health surveys and found that
taking the U.S. Recommended Daily Allowance of Vitamin D (400 IU/day) reduced
the risk of pancreatic cancer by 43 percent. By comparison, those who consumed
less than 150 IUs per day experienced a 22 percent reduced risk of cancer.
Increased consumption of the vitamin beyond 400 IUs per day resulted in no
significant increased benefit.
"Because there is no effective screening for pancreatic cancer, identifying
controllable risk factors for the disease is essential for developing strategies
that can prevent cancer," said Skinner.
"Vitamin D has shown strong potential for preventing and treating prostate
cancer, and areas with greater sunlight exposure have lower incidence and
mortality for prostate, breast, and colon cancers, leading us to investigate a
role for Vitamin D in pancreatic cancer risk. Few studies have examined this
association, and we did observe a reduced risk for pancreatic cancer with higher
intake of Vitamin D."
Skinner, currently in the Department of Population Health Sciences at the
University of Wisconsin School of Medicine and Public Health, and his colleagues
analyzed data from two long-term studies of health and diet practices, conducted
at Harvard University. They looked at data on 46,771 men aged 40 to 75 years who
took part in the Health Professionals Follow-up Study, and 75,427 women aged 38
to 65 years who participated in the Nurses' Health Study. Between the two
studies, they identified 365 cases of pancreatic cancer. The surveys are
considered valuable for their prospective design, following health trends
instead of looking at purely historical information, high follow-up rates and
the ability to enable researchers like Skinner to incorporate data from two
independent studies.
Pancreatic cancer is a rapidly fatal disease and the fourth-leading cause of
death from cancer in the United States. This year, the American Cancer Society
estimates that 32,000 new cases of cancer will be diagnosed. About the same
number of people will die this year from the disease. It has no known cure, and
surgical treatments are not often effective. Except for cigarette smoking, no
environmental factors or dietary practices have been linked to the disease.
In addition to Vitamin D, the researchers also measured the association between
pancreatic cancer and the intakes of calcium and retinol (Vitamin A). Calcium
and retinol intakes showed no association with pancreatic cancer risk, although
retinol is an antagonist of Vitamin D's ability to influence mineral balances
and bone integrity.
For that reason, further research is necessary to determine if Vitamin D
ingestion from dietary sources, like eggs, liver and fatty fish or fortified
dairy products, or through sun exposure might be preferable to multi-vitamin
supplements, which contain retinol.
The potential benefits of vitamin D for pancreatic cancer were only recently
established by other laboratory studies. Normal and cancerous pancreas tissue
contain high levels of the enzyme that converts circulating 25-hydroxyvitamin D
into 1,25-dihydroxyvitamin D, the vitamin's active form. Other studies have
shown an anti-cell proliferation effect of 1,25-dihydroxyvitamin D, potentially
inhibiting tumor cells.
"In concert with laboratory results suggesting anti-tumor effects of
Vitamin D, our results point to a possible role for Vitamin D in the prevention
and possible reduction in mortality of pancreatic cancer. Since no other
environmental or dietary factor showed this risk relationship, more study of
Vitamin D's role is warranted," Skinner said.
###
Skinner's colleagues in the study include Dominique Michaud, Edward Giovannucci,
Walter Willett and Graham Colditz of Harvard, and Charles Fuchs of the
Dana-Farber Cancer Institute.
The mission of the American Association for Cancer Research is to prevent and
cure cancer. Founded in 1907, AACR is the world's oldest and largest
professional organization dedicated to advancing cancer research. The membership
includes more than 24,000 basic, translational, and clinical researchers; health
care professionals; and cancer survivors and advocates in the United States and
more than 60 other countries. AACR marshals the full spectrum of expertise from
the cancer community to accelerate progress in the prevention, diagnosis and
treatment of cancer through high-quality scientific and educational programs. It
funds innovative, meritorious research grants. The AACR Annual Meeting attracts
over 17,000 participants who share the latest discoveries and developments in
the field. Special Conferences throughout the year present novel data across a
wide variety of topics in cancer research, treatment, and patient care. AACR
publishes five major peer-reviewed journals: Cancer Research; Clinical Cancer
Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer
Epidemiology, Biomarkers & Prevention. Its most recent publication, CR, is a
magazine for cancer survivors, patient advocates, their families, physicians,
and scientists. It provides a forum for sharing essential, evidence-based
information and perspectives on progress in cancer research, survivorship, and
advocacy.
(Sept. 2006) (Opm. Behalve op tijd lopen in de zon is voeding zoals vette vis en eieren een prima bron van vitamine D.)