NEW YORK (Reuters Health) - there is no convincing evidence that the fact to the high doses of selenium - a popular dietary supplement - can prevent cancer, according to a new review.
Selenium is a mineral that is essential for humans and is also present in the soil and rocks.
Although the recommendations of daily selenium of the United States and the World Health Organization vary between 30 and 55 micrograms per day for adults, the authors note, companies selling supplements claim that higher doses have a range of health benefitsincluding the prevention of cancer.
However, Mr. Marco Vinceti, one of the authors of the new journal of the University of Modena and Reggio Emilia, in Italy, "we have still not an accurate picture of what Selenium is for human health," said Reuters Health.
To try to get better attention on this image for cancer in particular, Vinceti and his colleagues reviewed 55 studies on the relationship between the different types of cancer and selenium.
Most of those that have so-called "observational studies" - scientists measured how much selenium people ate every day or how much they had in their blood or nails, then followed which has cancer over the next few years.
The other 6 studies have been conducted through more rigorous testing, in which researchers divided randomly participating in a group which took supplements of selenium for a month or more and the other took a pill without drug placebo or nothing - then follow their cancer. It is believed that these types of studies are better accounting of external factors that may affect cancer risk.
Observational studies suggested that speak of selenium can be linked to a slightly lower risk of cancer - both men and women.
But in randomized trials, people assigned to take selenium at doses at least four times higher that the daily recommendation were not less likely to get cancer - prostate cancer and cancer of the skin in particular - those taking not of selenium.
And some of these tests has raised the question of whether doses of selenium could be dangerous, such as increasing the risk of diabetes.
The journal is published in the Cochrane Library, a publication of the Cochrane Collaboration, an international organization that evaluates medical research.
"If you place all together, it is not a good story for patients," Dr. Neil Fleshner, researcher at the Toronto University health network who has studied the effect of selenium on the risk of prostate cancer, told Reuters Health.
He said that it is always possible that selenium may help prevent cancer over a very long time period, or some types of selenium could operate while others do not. But good, "exists now that no good not evidence at all that Selenium is beneficial," said Fleshner, who was not involved in the control.
James Marshall, of Roswell Park Cancer Institute in Buffalo, said that the enthusiasm of selenium began with the evidence that animals or people very low selenium in the diet are at an increased risk of cancer.
While people could benefit from a supplement of selenium, is where the anti-cancer effects of the mineral appear at the end.
"Once you get an animal or a person to a place where the intake of Selenium is adequate, then, this is where the evidence has proved disappointing,"Marshall, who was not related to the research, said Reuters Health."
"Put on more selenium will not make them any good, and it may in fact their wrong," said Marshall.
Vinceti said that although few people in Europe selenium as a supplement, it is common to the United States.
Selenium supplements are about $2 a month supply.
Vinceti added that additional research is needed to determine the range of daily selenium which is beneficial for human health - as both too and too few seem to have health risks. In this regard, we are not at the end of history", he said.
But when it comes to cancer prevention, at least for the moment, the evidence is not there.
"There are several ways of preventing cancer, but put more selenium...".on your breakfast cereals, is probably not one of them, "Marshall concluded."
SOURCE: http://bit.ly/iqHcFo The Cochrane Library, online on May 10, 2011.
No comments:
Post a Comment