Despite dietary supplements being popular among prostate cancer patients, a
new review of past research says they are not effective treatments for the
Pulling together data from eight randomised controlled trials - considered
the gold standard of medical research, researchers found non-herbal dietary
supplements and vitamins didn't significantly change the severity of people's
"The main message would be that no miraculous supplement for (prostate
cancer) exists," wrote Dr Paul Posadzki, the review's lead author from the Korea
Institute of Oriental Medicine in Daejeon, in an email to Reuters Health.
The American Cancer Society estimates that about 240 000 US men will be
diagnosed with prostate cancer in 2013, and about 30 000 will die from it.
According to the researchers, who published their results in the journal
Maturitas, it's estimated that between a quarter and three-quarters of patients
with prostate cancer take dietary supplements despite limited evidence of any
Some studies have looked at whether supplements - such as selenium - could
prevent cancers, but came up short.
To get a better picture of whether supplements are any good at treating
prostate cancer, the researchers reviewed trials that looked at minerals,
vitamin D, antioxidants and plant compounds known as isoflavones and
The researchers had information on 478 prostate cancer patients from eight
trials that were conducted in the Netherlands and the US.
The patients' prostate cancers varied across a scale that measures the
severity of cancer from 2 to 10 - with 10 being most severe. In each trial, the
patients took a supplement - which varied depending on the study - and were
tracked for a few weeks or up to five years.
Overall, six trials showed that the supplements didn't give patients benefit
over patients taking a placebo or another type of supplement.
Two studies did show a significant drop in prostate specific antigen levels -
a potential but controversial marker of cancer - among patients taking a
combination of supplements, compared to patients taking placebos.
However, neither of those studies included more than 50 people and both were
sponsored by supplement manufacturers.
"I do not think these supplement combinations could help and no supplement
can replace the balanced diet. By no means is the evidence conclusive," Posadzki
Dr Eric Klein, chair of the Glickman Urological and Kidney Institute at the
Cleveland Clinic in Ohio, said the new review's findings are consistent with
"I think if you survey the literature on nutritional supplements and cancer,
there is almost no evidence that they're helpful. In fact, some people have
found that there is evidence of harm," said Klein, who was not involved with the
"I think that until we get a better understanding of the biology of how
supplements affect normal and cancer cell growth, we should not invest in this
kind of research," he added.
Currently, the three main approaches to managing prostate cancer are active
surveillance, radiation and surgery.