Posted on 02/28/2007 2:45:16 AM PST by XR7
Vitamin supplements taken by millions of people every day for their health could be increasing their risk of death a new Danish-led study suggests.
The study is published in the Journal of the American Medical Association.
The international research team reviewed the published evidence on beta carotene, vitamin A, vitamin E, Vitamin C and selenium. The team was led by Dr Goran Bjelakovic, from Copenhagen University Hospital, Denmark.
These dietary supplements are marketed as antioxidants and people take them in the hope they will improve health and guard against diseases like cancer and heart disease by eliminating the free radicals that cause "oxidative stress" and damage and kill off cells.
Antioxidants are also marketed as anti-aging products because they are thought to slow down the aging process.
Some studies have suggested that antioxidants are beneficial to health, while others, mostly larger clinical trials, have concluded they have no effect on health and say in some cases that taking too many of them can be harmful.
In this study, Dr Bjelakovic and colleagues did a meta-analysis on research published before October 2005.
Meta-analysis is a way of sifting through published studies against a quality standard that looks at a number of reliability criteria such as potential for bias. Then the ones that pass the standard are taken through a statistical process to find out if they are saying something consistently reliable. There can be several levels of "sifting", each producing a more reliable and robust set of evidence.
In this case the researchers followed a method established by the Cochrane Collaboration, a group of 6,000 health care specialists who review biomedical trials and other research projects.
They started with 815 clinical trials of which 68 passed the first level of quality standard. At this level the results were inconclusive. The supplements were found to have no effect on death risk one way or the other.
They then went back and eliminated 21 of the trials, leaving only the "low-bias" ones. This was the next level of quality standard.
At this level of meta-analysis the results were different.
When looked at separately they found that Vitamin A increased death risk by 16 per cent, beta carotene by 7 per cent and Vitamin E by 4 per cent. The results for Vitamin C were not so clear, but by looking at the best quality trials there was a suggestion that it increased death risk by 6 per cent, either on its own or in combination with other supplements.
The figures from the best quality trials on selenium however showed that it might reduce death risk by 10 per cent, either on its own or in combination with other supplements, but this was not found to be statistically significant.
The overall conclusion of the study was that on balance, the best quality research shows that beta carotene, vitamin A and vitamin E may increase mortality risk, but vitamin C and selenium need further study.
A spokesperson for the supplements industry said the research was "flawed" because it included studies conducted on people who were already very sick.
The researchers say there are several potential reasons for these results. One is that the free radicals that are thought to cause the oxidative stress are the byproduct rather than the cause of disease. Another is that they may play an important role in the immune system and eliminating them could be counterproductive.
The researchers pointed out that the studies they examined only used synthetic supplements, and therefore their observations and conclusions do not apply to natural antioxidants such as those found in fruit and vegetables.
They added however that this study is important for public health reasons because between 10 and 20 per cent of people in Europe and North America take dietary supplements.
Nutritionists say that instead of taking supplements the best way to protect your health is to eat a balanced diet and to get all the vitamins you need from your food.
"Mortality in Randomized Trials of Antioxidant Supplements for Primary and Secondary Prevention; Systematic Review and Meta-analysis." Goran Bjelakovic, Dimitrinka Nikolova, Lise Lotte Gluud, Rosa G. Simonetti, and Christian Gluud. JAMA 2007;297:842-857. Vol. 297 No. 8, February 28, 2007
I intend to live forever. So far, so good. ~Steven Wright
ABSOLUTELY!!! The error I see in many medical papers is CAUSALITY. Sick people often try megadoses as medication. Just because there is correlation does not mean that supplements cause the increased mortality. The major drug companies have been on a campaign for decades against supplements because supplements supplant expensive prescription drugs. For example, I tore my achilles tendon while packing a friend's deer out of the mountains. My orthopods were unable to do anything for me. After 4 years of being incapacitated I heard about glucosamine-chondroitin; my torn tendon grew back in 3 months.
> I'd guess that sick people are more likely to take supplements, so, naturally, people that take supplements are at increased risk. What is the evidence of causality? <
Excellent point! And that's why one should always be skeptical of studies that aren't based on large, randomized samples and even better, a "double-blind" methodology.
Ever considered going to the feed store and buying a mineral block to keep on your desk? Has more flavor than a tin can.
The only proven miracle pill is good old aspirin.
The key is moderation. A little extra Vitamin C does you good, a lot can kill you.
Not really. There does not seem to be any fatal oral dose of Vitamin C.
Isn't this saying, they threw out the studies that didn't back up their desired outcome?
bump
Now if large numbers of liberals would only start carrying firearms for their self-defense, the gun control crowd would be stymied. The Second Amendment would become as sacrosanct as the First Amendment, and authorities would have to strain to find some reason to ban private ownership of modern artillery and combat aircraft.
Kinda like Gore throwing out the cold temperatures.
sw
but they say now that these 'free radical scavengers' do nothing really benificial . And, per usual, I just bought Vit A for the first time today cuz my eyes are getting bad, I get home and then see this article lol-
thanks, bfl
Next year, the research will show vitamins are good for you. Coffee will be bad, again, and tea will kill the kidneys. Every time I see counter research I wonder where the money goes. Moderation is the answer. Don't overdose on anything that is food based resources et al, and one will probably be OK>.
Fish oil increases the risk of hemorrhagic stroke and can interfere with blood clotting.
Sorry. Fish oil has been proven to have all kinds of benefits. To warn about fish oil and to ignore aspirin, etc. is absurd.
I don't believe it.
The medical establishment doesn't want us treating ourselves.
There is a well known clinic in Wichita that uses it a lot but that is seven hours from us.
There have been threads on FR regarding IV Vit C and cancer. If I get cancer I am not going to have chemo, etc. I'll do intravenouse Vit C and other alternative therapies. Johanna Budwig has an interesting diet. It seems to have legitimacy. Heat has shown to be promising.
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