April 5, 2008

Vitamin Use Greater In Those With Chronic Disease

A new study by the National Cancer Institute has found that people with one or more chronic illness are the primary factor behind the use of dietary supplements. Cancer survivors also contribute to the use of supplements, although not specifically as cancer treatments.

Dr. Melissa Farmer Miller, the study's lead author, told Reuters that its important for cancer patients to inform their physicians about any non-prescription medications or natural products they may be taking, as a lack of information exists on the risks and benefits of many supplements. In addition, there may be potential for drug interactions with medications, such as tamoxifen, that many cancer survivors may be taking.

"We really are just beginning to build an evidence base on the benefits of dietary supplements," said Miller, of the National Cancer Institute in Bethesda, Maryland.

"Even if there's not a benefit, there is a potential for them to cause harm," she said, noting that the use of supplements is growing among all Americans.

To determine whether cancer survivors are using supplements at greater rates than the general population, Miller and her team analyzed information from 1,844 cancer survivors and compared it with a random sampling of 7,343 people with no history of cancer.

The team found that vitamins were the only type of supplement use independently associated with having a cancer diagnosis. However, those participants with a  chronic illness were 82 percent more likely than those without a chronic disease to be using two or more supplements, regardless of whether or not they also had cancer.

Other factors associated with the use of dietary supplements were greater physical activity, consumption of fruits and vegetables, being female, being of older age and the use of other alternative and complementary medicines.

Miller said it was not possible at this time to conclude whether or not people living with cancer should either take supplements, or avoid them.

"The primary message should always be to promote a healthy diet," she said.

She said that doctors and other cancer patient caregivers should be up to date on the literature about various supplements, and should be aware of any supplements their patients may be taking. Cancer patients should also be informed as much as possible about any supplement before they take it, Miller added, noting that it can often be tough due to the lack of regulatory oversight of dietary supplements in the U.S. and the  limited information available on their risks and benefits.

"Consumers are really kind of out there on their own, and should confer with their health care providers about supplement use."

Dr. Miller"Ëœs report was published in the March 2008 issue of the Journal of the American Dietetic Association. 

A summary of the report can be viewed at http://www.adajournal.org/article/S0002-8223(07)02206-7/abstract.