Tuesday, October 27, 2015
The latest anti-oxidant controversy
Medscape article re selenium/Vit E and Prostate cancer - 2014
This article from last year notes..."data from the much publicized Selenium and Vitamin E Cancer Prevention Trial (SELECT), which sought to determine whether these supplements could protect against the development of prostate cancer, confirm that both antioxidants can be risky business for men. ...men receive no preventive benefit from either selenium or vitamin E supplements; in fact, for certain men, these supplements actually increased the risk for prostate cancer." A researcher interviewed noted, "Many people think that dietary supplements are helpful or at the least innocuous. This is not true."
"The cohort of 4856 men was culled from SELECT, the larger phase 3 placebo-controlled trial in which more than 35,000 men were randomized to high-dose vitamin E (400 IU/day) and/or selenium (200 µg/day) supplements. SELECT began in 2001 and was expected to run for 12 years, but it was stopped early, in 2008, after participants had been on the supplements for an average of 5 years. The results demonstrated that there was no protective effect from selenium and suggested that vitamin E increased prostate cancer risk. Although the use of the supplements stopped, the study actually continued. After 2 years of follow-up, the men who took vitamin E had a statistically significant 17% increased risk for prostate cancer. Notably, the rate of prostate cancer detection was higher in the groups that received either supplement alone or a combination of the 2 than in the placebo group (but the difference was significant only in the vitamin E group)."
Medscape re antioxidants and melanoma - 2015
This article published October 23 reports...."though the data are preliminary, findings from a new study may shed some light on why supplementing with antioxidants may be a bad idea for patients with cancer."
"Our data suggest cancer cells benefit more from antioxidants than do normal cells," said lead author Sean Morrison, PhD, director of the Children's Research Institute and Mary McDermott Cook Chair in Pediatric Genetics at UT Southwestern Medical Center in Dallas, Texas. "It raised the concern that people with cancer may want to think twice before they supplement their diet with large doses of antioxidants."
In their study, human melanoma cells taken from several patients were [grafted into mice] In mice that were given the antioxidant N-acetyl-cysteine, cancer spread was accelerated. It significantly increased the frequency of melanoma cells in the blood of some of the mice and significantly increased metastatic disease burden in all of them. "At least in the mice, the antioxidants promoted the capacity of the cancer cells to spread and metastasize," he said.
The authors found that that metastasizing melanoma cells experience very high levels of oxidative stress, which in turn leads to the death of most of these cells. Oxidative stress therefore limits distant metastasis by melanoma cells. But by administering antioxidants to the mice, more of the metastasizing melanoma cells were able to survive and increase the metastatic disease burden.
Even though this study was done in mice, Dr Morrison feels that the results can be extrapolated to humans. "We have previously shown that the behavior of human melanomas in mice are predictive of how melanoma behaves in humans. ... But it is important to remember that our study was performed in mice and not in actual human patients."
The report goes on to reference the report above as well as one in which patients with lung cancer were given selenium or not. Those who were given the supplement had a greater incidence of a second tumor, "but it was not statistically significant and therefore could have been due to chance."
Another study looked at [genetics] to shed more light on which population of men who already have prostate cancer might be most harmed by selenium. Among men with the AA genotype, higher selenium levels were associated with a 40% reduced risk of presenting with aggressive disease, whereas among men with the V allele, higher selenium levels were associated with an almost doubling of the risk for aggressive disease. Phillip Kantoff, MD, director of the Lank Center for Genitourinary Oncology, and vice chair and chief, Division of Solid Tumor Oncology, Department of Medical Oncology at the Dana-Farber Cancer Institute in Boston, Massachusetts, was the senior author on the genetic study. [When interviewed, he noted:] "The study is interesting. There is a fair amount of data supporting this. In fact, there are 2 follow-up studies of SELECT study showing that over time the arms that got vitamin E or selenium had more or more aggressive cancers."
"The underlying mechanism is still not clear but this is one possible one," Dr Kantoff added.
And then there was this about Vitamin D: Vitamin D and melanoma
Bottom line: I think there is much we don't understand about many things....and that certainly includes the behavior of cancer cells . I have NEVER been one to recommend boat loads of vitamins and supplements; just because a little is good doesn't mean a lot is better! As a rather brilliant nursing professor I had noted, "Americans have the most expensive urine in the world." Referencing the fact that most water soluble vitamins are simply excreted by the body and the money we paid for them is literally dollars down the drain. These reports as well as other previously existing data warn that supplements can also cause harm. If I were a man with prostate cancer, I certainly wouldn't be taking selenium and Vitamin E supplements. On the other hand, I see no need to panic. We have also long known that folks who eat a well balanced diet, heavy in fruits and vegetables, and get regular exercise, lead longer, healthier lives with less incidence of heart disease, cancer, and dementia than those who do otherwise. I see nothing scary in an orange. And, melanoma or no, that is the path I will continue to follow.
Eat your colors! - c