Supplements OK for Cancer Survivors?
Three-Fourths of Older Cancer Survivors Take Supplements; Researchers Advise Caution
By
Kathleen Doheny
WebMD Health News
Reviewed By
Louise Chang, MD
Aug. 12, 2008 — Dietary supplement use among long-term cancer survivors
aged 65 and older is very common, according to a new study. But researchers say
the practice may pose risks, even though the goal is often to prevent cancer
recurrence.
"When you supplement, particularly one specific type of nutrient, you
can upset the metabolic balance, how the body processes those nutrients,"
says Denise Snyder, RD, the clinical trials manager at the Duke University
School of Nursing and a study co-author. "Maybe you have too much of one
thing, not enough of something else, and that may put your cells at risk."
For the study, published online in the Journal of Cancer
Survivorship, Snyder and colleagues asked 753 cancer survivors who were
five years or more out from their diagnosis of breast, prostate, or colorectal
cancer to answer questions by telephone about their dietary habits and
their use of supplements.
Supplements for Cancer Survivors
Seventy-four percent of the survivors reported taking dietary supplements.
Of these:
- 80% took a multivitamin.
- 50% took calcium, vitamin D, or both.
- 41% took antioxidants such as vitamins C and E, carotenoids, selenium, and
combinations.
- 29% took fish oil or fatty acid supplements.
- 19% took glucosamine, chondroitin, and combinations.
- 18% took botanicals or herbs.
Ninety percent of those who used supplements reported using at least one
formulation for more than a year.
The numbers taking supplements were a surprise, Snyder says. "We kind of
expected it would be at least half," she tells WebMD.
Supplement use was tied into diet habits and other lifestyle factors,
Snyder's team found. In general, the healthier the lifestyle, the more
likely the survivors were to take supplements.
Those who ate a high amount of fruits, vegetables, and fiber and less
saturated fat than the others tended to use supplements. Nonsmokers and the
more highly educated participants were also more likely to report supplement
use.
Supplements for Cancer Survivors: Analysis
Turning to dietary supplements after cancer treatment is understandable,
says Snyder. Cancer survivors tend to look for something they hope will reduce
the odds of recurrence or a new cancer, she says.
"They have often reached out to supplements as a backup to a healthy
diet," she tells WebMD. The researchers didn't ask why the cancer
survivors took the supplements, she says.
Supplements OK for Cancer Survivors?
While dietary supplements may help fill in nutrients lacking in a person's
diet — particularly in the diets of seniors, which can fall short — Snyder
warns that risks are also associated with supplement use.
"I'm recommending that people not self-supplement," Snyder tells
WebMD. The supplements may backfire in preventing cancer recurrence, she
says.
For instance, she writes in the paper, calcium intakes of 1,500 milligrams
or more a day may be associated with an increased risk of aggressive prostate
cancer.
And research has found that those at high risk of getting lung cancer aren't
helped by a combination of beta-carotene and vitamin A and in fact had
increased lung cancer incidence, she says.
The American Institute for Cancer Research and the World Cancer Research
Fund recommend against supplements to protect against cancer.
The bottom line, Snyder says: "Talk to your doctor or meet with a
registered dietitian, someone who can help you evaluate whether you need a
supplement or not."
Supplements for Cancer Survivors: Use Caution
Having a conversation with your health care professional about whether you
need a supplement or not is wise, whether you are a cancer survivor or not,
says Len Lichtenfeld, MD, deputy chief medical officer for the American Cancer
Society.
Because the people in the study were all five years removed from their
cancer diagnosis, he says, "there is no need to treat cancer survivors at
this point in their journey any differently" than non-survivors.
Even so, he recommends talking to your doctor or other health care
professional to be sure, for instance, that the supplements you want to take
won't adversely affect your medications.
More study is needed on supplement use among survivors, he says. "What
isn't known is supplement use's effect on cancer relapse; that is up in the
air."
Many of the supplements taken by the survivors, such as multivitamins,
calcium, vitamin D and fish oil, probably pose little risk when not taken in
large doses, says Christine Gerbstadt, MD, RD, a spokeswoman for the American
Dietetic Association. "If you really think you need a supplement, you
probably can't go wrong taking a multivitamin, calcium and D, and fish oil. But
if you are eating two to three fish servings a week, you probably don't need
the fish oil."
Industry's view
There are little data on the role of supplements in helping cancer survivors
remain cancer free, says Andrew Shao, PhD, vice president of scientific and
regulatory affairs for the Council for Responsible Nutrition, a trade group
based in Washington, D.C. "Most of the data on nutrient intake in cancer risk
is on primary prevention," that is, preventing a first cancer, he tells
WebMD.
For that reason, he says, "The Council does not have a specific
recommendation on supplements for cancer survivors."
But he agrees with Lichtenfeld that at the five-year mark the advice is
probably no different for survivors than for the general population.
Of the supplements used by the older cancer survivors in the study, he says:
"There is no reason to think these would be harmful."
SOURCES: Miller, P. Journal of Cancer Survivorship, published online July 11,
2008. Denise Snyder, RD, clinical trials manager, Duke University School of
Nursing, Durham, N.C. Len Lichtenfeld, MD, deputy chief medical officer, American Cancer Society,
Atlanta. Christine Gerbstadt, MD, RD, spokeswoman, American Dietetic Association. Andrew Shao, PhD, vice president of scientific and regulatory affairs,
Council for Responsible Nutrition.
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