A new study, published inthe Journal of the
American Medical Association looked at whether supplementing
with calcium and vitamin D reduces cancer risk.
Increasing vitamin D levels may lower the risk for developing
cancer, according to a study conducted by Creighton University
with cooperation from the University of California San Diego.
The results of the study were released today in the Journal of
the American Medical Association. The study, funded by the
National Institutes of Health, is a randomized clinical trial
of the effects of vitamin D supplementation on all types of
Related: Getting Enough Vitamin D
The four-year study included 2,303 healthy postmenopausal women
55 years and older from 31 counties in Nebraska. Participants
were randomly assigned to take either 2000 international units
(IU) of vitamin D3 and 1500 mg. of calcium or identical
placebos daily for 4 years. The vitamin D3 dose was about three
times the US government’s Recommended Dietary Allowance (RDA)
of 600 IU for adults through age 70, and 800 IU for those 71
Women who were given vitamin D3 and calcium supplements had 30
percent lower risk of cancer. This difference in cancer
incidence rates between groups did not quite reach statistical
significance. However, in further analyses, blood levels of
vitamin D, specifically 25-hydroxyvitamin D (25(OH)D), were
significantly lower in women who developed cancer during the
study than in those who remained healthy.
The average 25(OH)D level in the women’s blood at the beginning
of the study (33 nanograms/milliliter, ng/mL) was higher than
the usual target levels that currently range from 20-32 ng/ml,
according to different sources. This suggests that higher
vitamin D levels than are currently recommended are needed for
substantially decreasing risk of cancer.
“This study suggests that higher levels of 25(OH)D in the blood
are associated with lower cancer risk”, said principal
investigator Joan Lappe, PhD, RN, Creighton University
Criss/Beirne Professor of Nursing and Professor of Medicine.
“The study provides evidence that higher concentrations of
25(OH)D in the blood, in the context of vitamin D3 and calcium
supplementation, decrease risk of cancer.”
These results contribute to a growing body of scientific
findings, including results of a similar randomized controlled
clinical trial preceding this one in Nebraska women, that
indicate that vitamin D is a critical tool in fighting cancer.
It is also of value in preventing other diseases, according to
Other Creighton researchers involved in the study included
Robert Recker, M.D., Dianne Travers-Gustafson, Ph.D., R.N., and
Patrice Watson, Ph.D. University of California San Diego
Professors Cedric F. Garland, Dr.P.H., F.A.C.E. and Edward D.
Gorham, Ph.D., were co-investigators. Professor Robert P.
Heaney of Creighton University, who died August 6, 2016, played
a key role in inspiring and planning this study. Heaney was the
acknowledged world expert on the physiology of vitamin D and
calcium and their relationship to several major diseases.
According to Lappe, most cells in the body need vitamin D to
function properly. Without adequate vitamin D, normally
functioning cells can convert to malignant cells.
Cedric Garland, a co-investigator at the University of
California San Diego said “This is the most important
scientific study of this century to date”.
The study was open to all ethnic groups, but most of the
participants were Caucasian, which Lappe said matched the
population in the rural counties in Nebraska. She said further
studies are needed to determine if these research results apply
equally to men and to other ethnic groups.
“While people can make their own vitamin D3 when they are in
the sun near mid-day, sunscreen blocks most vitamin D
production. Also, due to more time spent indoors, many
individuals are lacking adequate levels of vitamin D compounds
in their blood,” Lappe said. “The results of this study lend
credence to a call for more attention to the importance of
vitamin D in human health and specifically in preventing
cancer” Lappe said.
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