Vitamin D study suggests no mortality benefit for older women

November 01, 2011

PROVIDENCE, R.I. [Brown University] -- Doctors agree that vitamin D promotes bone health, but a belief that it can also prevent cancer, cardiovascular disease and other causes of death has been a major health controversy. Consistent with advice issued last fall by the Institute of Medicine, a new study finds that vitamin D did not confer benefits against mortality in postmenopausal women after controlling for key health factors such as abdominal obesity.

"What we have is clinical trial evidence that for the most part vitamin D doesn't seem to be helpful for conditions where people thought it might," said study lead author Charles Eaton, professor of family medicine and of epidemiology in the Warren Alpert Medical School of Brown University and a physician at Memorial Hospital in Pawtucket, R.I. "The best we can tell is that there isn't an association. Once we took into account these other factors, high levels didn't provide a benefit and low levels didn't put you at risk."

In the study, published online Oct. 26 in the American Journal of Clinical Nutrition, Eaton led an analysis of data from 2,429 postmenopausal women aged 50 to 79 who participated in the broad-based Women's Health Initiative study, in which Eaton and many co-authors were investigators. They tracked blood levels of vitamin D in the women and their mortality over a 10-year period. They not only looked at death from all causes but also focused on cancer and cardiovascular disease.

In all, 225 of the women died, including 79 from cardiovascular disease and 62 from cancer.

Eaton said he expected to find some protective effect against such mortality from vitamin D, and at first glance -- controlling only for age, ethnicity, and whether women took part in a calcium and vitamin D supplement trial -- that's what the data showed. But what was apparent in the data was that the women with the lowest levels of vitamin D also had a lot of other negative health indicators. The team therefore controlled for several more key health factors, such as smoking, history of cardiovascular disease, history of cancer, alcohol consumption, and waist circumference. The additional controls, especially waist circumference, which is a measure of abdominal obesity, eroded the statistical significance of vitamin D's seemingly protective effects down to nothing.

The one exception was that women with thinner waistlines (less than 35 inches) and with the lowest vitamin D levels seemed to have a greater risk of "all-cause" mortality within the 10-year analysis period. That result, however, was right on the borderline of statistical significance.

"If you are thin, this data suggest that maybe low vitamin D levels are potentially harmful and you should talk to your doctor about what to do about them," Eaton said.

Eaton said he and his co-authors can only speculate about why abdominal obesity was an especially important and powerful factor to control for in their analysis. In the study they note that abdominal obesity is associated with several negative health indicators that may overwhelm any modest benefit vitamin D might have. They also point out that fat tissue can store vitamin D, possibly meaning that women with larger waistlines are storing more of the vitamin than their blood serum levels alone would reveal.

More research into the connections between abdominal fat and the health effects of vitamin D could help resolve the question, Eaton said. He also said that a major new trial of vitamin D supplements and health called "VITAL" is getting underway and will likely inform the broader controversy about what vitamin D is good for.

For now, Eaton said, "there's not enough evidence to do anything about our vitamin D levels if it's not in regard to bone health."
-end-
The other authors on the paper are Anne McTiernan and Alicia Young of the Fred Hutchinson Cancer Research Center in Seattle; Matthew Allison of the University of California-San Diego; Jennifer Robinson of the University of Iowa; Lisa Martin of the George Washington University Medical Center; Lewis Kuller of the University of Pittsburgh; Karen Johnson of the University of Tennessee; J. David Curb of the University of Hawaii; Linda Van Horn of Northwestern University; Simin Liu of the University of California-Los Angeles; and JoAnn Manson of Harvard Medical School.

The Women's Health Initiative was funded by the National Heart, Lung and Blood Institute.

Brown University

Related Cancer Articles from Brightsurf:

New blood cancer treatment works by selectively interfering with cancer cell signalling
University of Alberta scientists have identified the mechanism of action behind a new type of precision cancer drug for blood cancers that is set for human trials, according to research published in Nature Communications.

UCI researchers uncover cancer cell vulnerabilities; may lead to better cancer therapies
A new University of California, Irvine-led study reveals a protein responsible for genetic changes resulting in a variety of cancers, may also be the key to more effective, targeted cancer therapy.

Breast cancer treatment costs highest among young women with metastic cancer
In a fight for their lives, young women, age 18-44, spend double the amount of older women to survive metastatic breast cancer, according to a large statewide study by the University of North Carolina at Chapel Hill.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Stress in cervical cancer patients associated with higher risk of cancer-specific mortality
Psychological stress was associated with a higher risk of cancer-specific mortality in women diagnosed with cervical cancer.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Moffitt Cancer Center researchers identify one way T cell function may fail in cancer
Moffitt Cancer Center researchers have discovered a mechanism by which one type of immune cell, CD8+ T cells, can become dysfunctional, impeding its ability to seek and kill cancer cells.

More cancer survivors, fewer cancer specialists point to challenge in meeting care needs
An aging population, a growing number of cancer survivors, and a projected shortage of cancer care providers will result in a challenge in delivering the care for cancer survivors in the United States if systemic changes are not made.

New cancer vaccine platform a potential tool for efficacious targeted cancer therapy
Researchers at the University of Helsinki have discovered a solution in the form of a cancer vaccine platform for improving the efficacy of oncolytic viruses used in cancer treatment.

American Cancer Society outlines blueprint for cancer control in the 21st century
The American Cancer Society is outlining its vision for cancer control in the decades ahead in a series of articles that forms the basis of a national cancer control plan.

Read More: Cancer News and Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.