Vitamin C vs. Heart Disease and Cancer

[X]

I was listening to the radio today, and there was a guest on explaining his "groundbreaking" medical discovery.

He was claiming that vitamin C prevents and cures cancer, heart disease, and other ailments.
He says the government is intentionally making Candian citizens ill by recomending we only take the minimum amount of vitamin C per day necessary to prevent scurvy.
He claims that growing studies (uncited) show that more vitamin C will prevent and cure the most common or scary causes of illness or death, chief among them heart disease and cancer.

I am not a medical expert, nor do I particularly care to be. Doesn't interest me.
However, this fellow's claims set off my skeptisenseTM.

Can anybody fill me in on whether this guy is correct in his claims or is off his rocker?

[Amapola]

This is from the SkepDic (Skeptic's Dictionary):

July 8, 2002. A five-year study involving more than 20,000 people aged 40 to 80 found that a daily dose of vitamin C, vitamin E and beta carotene does not reduce the risk of heart disease, cancer, or mental decline. Prof Rory Collins, a co-author of the report at Oxford University's Clinical Trial Service, said: "Over five years we saw absolutely no effect." At the end of the trial, people taking vitamins had exactly the same risk of heart disease, cancer, cataracts, bone fractures, asthma and mental decline as those who took a placebo. In contrast, cholesterol-lowering drugs reduced the risk of heart disease and stroke by around one third.

Here's the link to the article this came from: link (http://www.telegraph.co.uk/news/main.jhtml;$sessionid$4ZRRWXIAAGGTXQFIQMFSFFWAVCBQ 0IV0?xml=/news/2002/07/05/nvit05.xml&sSheet=/news/2002/07/05/ixnewstop.html&_requestid=65203&_requestid=312104)

This idea has been around for a long time. I remember being told this very thing 30 years ago. A bunch of people I knew took "mega-doses" of vitamin C. Over the years they proceeded to die of heart disease and cancer at the same rates as other people.

I think your best bet on preventing heart disease and cancer is good genetics. Sorry.

[X]

I think your best bet on preventing heart disease and cancer is good genetics. Sorry.


Don't be. I'm covered on the genetics part. ;)

[shadron]

The theory was that anti-oxidants (vitamins e, c, beta-carotene and some others) would scavenge oxidizers within cells, preventing them from damaging proteins and DNA by inappropriately altering them. The theory added that such oxidations were typical of the start of cancerous growth.

As Amapola says, it didn't prove out in clinical testing. That, of course, doesn't stop the health additives makers from continuing to push them. And, also of course, Linus Pauling, the Nobel-winning chemist, swore by megadosage vitamin C, which is the classic case of a promising cure not making the step from the test tube to the body.

[Deetee]

;3656393']I was listening to the radio today, and there was a guest on explaining his "groundbreaking" medical discovery.

He was claiming that vitamin C prevents and cures cancer, heart disease, and other ailments.

As indicated, trials have failed to confirm what might have been a plausible hypothesis.
The most recent evidence comes from a large meta-analysis (http://www3.interscience.wiley.com/homepages/106568753/CD007176.pdf) which showed:
Overall, the antioxidant supplements did not seem to reduce mortality. A total of 17880 of 136,023 participants (13.1%) randomised to antioxidant supplements and 10136 of 96527 participants (10.5%) randomised to placebo or no intervention died. In the analyses of the trials with low risk of bias, beta-carotene, vitamin A, and vitamin E significantly increased mortality. There were no significant differences between the effects of antioxidant supplements in healthy participants (primary prevention trials) or participants with various diseases (secondary prevention trials). Randomised trials with adequate bias control found no significant effect of vitamin C. In some of our analyses, selenium seems to reduce mortality.

My bold.

Discussed here (http://forums.randi.org/showthread.php?t=111478).

[MRC_Hans]

;3656393']I was listening to the radio today, and there was a guest on explaining his "groundbreaking" medical discovery.

He was claiming that vitamin C prevents and cures cancer, heart disease, and other ailments.
He says the government is intentionally making Candian citizens ill by recomending we only take the minimum amount of vitamin C per day necessary to prevent scurvy.
He claims that growing studies (uncited) show that more vitamin C will prevent and cure the most common or scary causes of illness or death, chief among them heart disease and cancer.

I am not a medical expert, nor do I particularly care to be. Doesn't interest me.
However, this fellow's claims set off my skeptisenseTM.

Can anybody fill me in on whether this guy is correct in his claims or is off his rocker?(my bolding)

The bolded part is a sure-fire woo indicator. So, government, struggling with rising health-care costs to make budget ends meet, deliberately ignores a cheap and readily available cure-all, and opts to keep the population sick instead? Yeah! :nope:

Hans

[Cuddles]

It's interesting to note that it's always vitamin C, and almost never any other vitamins, that is claimed to cure everything. The simple reason for this is that vitamin C seems to be one of the few things that is genuinely impossible to overdose on. Anyone telling people to take massive doses of vitamin A, for example, would soon be in serious trouble since taking just twice the RDA can result in toxicity.

Vitamin C is easy for woos to make claims about because everyone already knows they need it and many people probably feel guilty about not eating enough fruit. Telling them that they need even more than they think isn't such a big jump for people to believe. Since many people don't get enough vitamins, and since it is apparently impossible for vitamin C to hurt anyone, there can be apparent benefits without any drawbacks, and so the woo about vitamin C continues.

[casebro]

...Since many people don't get enough vitamins...

Evidence? Or have you fallen for more Woo?

[soylent]

It's interesting to note that it's always vitamin C, and almost never any other vitamins, that is claimed to cure everything.

Quite often it's "vitamin B-17" which seems to be the new "brand name" for the old amygdalin/laetrile scam.

[Bikewer]

It was Linus Pauling, the Nobel laureate, who started to promote this idea in his dotage. He sold books, went on the talk-show circuit, did the whole thing. Folks took him seriously for a while; Nobel laureate and all...

Alas, no one was able to reproduce any of of his claimed effects or duplicate his findings in any way. Subsequent in-depth studies have utterly quashed the idea of "megavitamins".

Unfortunately, such ideas tend to live on....

[JJM]

Go to www.quackwatch.org (http://www.quackwatch.org) and search for "orthomolecular", "pauling", "vitamin c" (separately, without the quotes).

I expect the safety of high-dose vitamin is discussed there. I do know that high doses cause diarrhea. In a broadcast interview shortly before he died, Linus Pauling said that he takes 50% more of it than he recommends to the public because "it has a nice, laxative effect."

[robinson]

In some sort of irony, Pauling died of prostate cancer. He was 93, but my Grandpa lived to the same age, and never took a vitamin in his life, or ate any health food.

[safe as milk]

three years later...

i'd like to post some skepticism to the skepticism.

the study referred to above was fully titled MRC/BHF Heart Protection Study of cholesterol-lowering therapy and of antioxidant vitamin supplementation in a wide range of patients at increased risk of coronary heart disease death: early safety and efficacy experience

1) they gave the patients 250 mg of vitamin c per day. that's not even close to the levels advocated by mega-dose vitamin c proponents. pauling, for example, recommended 6 - 18 grams of vitamin c per day.

2) it was funded by merck and schering-plough who obviously had a stake in the outcome.

i'm not allowed to post links but you can find the original study on the lancet website.

[fls]

http://www.ncbi.nlm.nih.gov/pubmed/12114037

[icerat]

http://www.ncbi.nlm.nih.gov/pubmed/12114037

while the OP claims are obviously woo, that study isn't much better, at least based on the abstract. It claims to be looking at whether supplementation helps incidence rates of various diseases, and then examines it by looking at a sample who were already sick

Sensible nutritional models are generally about prevention, not treatment.

[fls]

while the OP claims are obviously woo, that study isn't much better, at least based on the abstract. It claims to be looking at whether supplementation helps incidence rates of various diseases, and then examines it by looking at a sample who were already sick

Sensible nutritional models are generally about prevention, not treatment.

It was a link to the results of the study mentioned in the prior post, rather than something I chose as illustrative. However, the outcomes (besides mortality) were vascular disease and cancer in those without cancer (maybe) or vascular disease, which would be primary and secondary (prevention of new disease in the presence of risk) prevention. Prevention of the progression of disease (those who already had heart attacks, etc.) in those already with vascular disease would be tertiary prevention. It is reasonable to wonder whether the mechanisms are different for those different kinds of prevention and it is reasonable to suspect that nutritional effects will be greater at the level of primary prevention. It is also reasonable to suspect that you have a greater chance of demonstrating an effect in a population where the outcome is common, rather than rare.

Linda

[icerat]

It was a link to the results of the study mentioned in the prior post, rather than something I chose as illustrative. However, the outcomes (besides mortality) were vascular disease and cancer in those without cancer (maybe) or vascular disease, which would be primary and secondary (prevention of new disease in the presence of risk) prevention. Prevention of the progression of disease (those who already had heart attacks, etc.) in those already with vascular disease would be tertiary prevention. It is reasonable to wonder whether the mechanisms are different for those different kinds of prevention and it is reasonable to suspect that nutritional effects will be greater at the level of primary prevention. It is also reasonable to suspect that you have a greater chance of demonstrating an effect in a population where the outcome is common, rather than rare.

Linda

In a megadose study that might be appropriate (still unlikely, imo to get any results), however in the supplementation levels they're talking about in that study it's more than likely (a) any "damage" from nutrient insufficiency that may or may not have occurred would have developed long before the study onset (b) existing lifestyle issues - which include accepted links between diet and these diseases - will further confound any effect.

In other words, we're long past primary prevention.

Even if supplementation was useful, I would be surprised to see any effect in a study of this type.

Having said that, I think human nutrition is such a complex area, full of interactions, that I think it may simply be too hard at this stage (or at least, too expensive) to really come up with quality studies.

On the other hand I think if any isolated vitamins had a "silver bullet" effect on particular diseases other than those we already know of (eg C and scurvy) then it would have been found by now.

[blutoski]

It's interesting to note that it's always vitamin C, and almost never any other vitamins, that is claimed to cure everything. The simple reason for this is that vitamin C seems to be one of the few things that is genuinely impossible to overdose on.

My theory is a bit different. Vitamin C is highly commoditized and there is an abundant competitive production environment with razor-thin margins. This means it's one of the cheapest vitamins to buy in bulk and has a high markup between wholesale and retail.





Anyone telling people to take massive doses of vitamin A, for example, would soon be in serious trouble since taking just twice the RDA can result in toxicity.

Vitamin C is easy for woos to make claims about because everyone already knows they need it and many people probably feel guilty about not eating enough fruit. Telling them that they need even more than they think isn't such a big jump for people to believe. Since many people don't get enough vitamins, and since it is apparently impossible for vitamin C to hurt anyone, there can be apparent benefits without any drawbacks, and so the woo about vitamin C continues.

The antioxidant vitamins like vitamin C do have a carcinogenic threshold, which means it's not impossible to overdose. But these are large doses over long time periods to increase risk even 1%. Overdose takes serious effort.

The physiology is understood: the immune system's mechanism for killing the bad guys -tumour cells, virus particles, bacteria - is to oxidize them. Antioxidants make the oxidation mechanism of the immune system less effective, and over time, the reduced tumour surveillance translates into a higher cancer risk.

But it takes a lot of antioxidant to create a statistical effect.

[icerat]

But it takes a lot of antioxidant to create a statistical effect.

Do you know if this effect has actually been shown, or just theorized?

[casebro]

Didn't a study show that vitamin E, via some of the caratenes, raised the cancer risk?

[icerat]

Didn't a study show that vitamin E, via some of the caratenes, raised the cancer risk?

carotenes are associated with A, not E. There was however a study linking A+beta-carotene supplements with an increase in cancer in smokers and ex-smokers. This was later confirmed and narrowed to Vitamin E.

Funnily enough, given the OP, one of the reasons may be that smokers are at greater risk of Vitamin C deficiency (http://www.ncbi.nlm.nih.gov/pubmed/19675106)

[blutoski]

Do you know if this effect has actually been shown, or just theorized?

Good question, and I would say no, not proven: the theory is attempting to explain clinical outcomes that show an elevated cancer risk in patients megadosing on vitamin C. These experiments were not designed to test this hypothesis - the hypothesis followed the observations.

The first alternative theory is that vitamin C combines with fats in the diet to form carcinogenic nitrosamines or lipid hydroperoxides. My impression is that this hypothesis is less plausible, and the supporting research looks weak.

The second alternative theory is that vitamin C increases cytokine production in tumour cells, which in turn attracts macrophages and growth factors. I'd rank this as the 2nd most plausible mechansim.

Third alternative theory (most recently proposed - 2009) is that since reactive oxygen species are necessary to faciliate macrophage clonal expansion, antioxidants in general may dampen immune response.


The point, I guess, is that megadoses of vitamin C seem to increase the risk of certain cancers, mechanism unproven, but most plausibly partial neutralization of Tk oxidation.

[icerat]

Good question, and I would say no, not proven: the theory is attempting to explain clinical outcomes that show an elevated cancer risk in patients megadosing on vitamin C. These experiments were not designed to test this hypothesis - the hypothesis followed the observations.

Ok, but at least there's some evidence. Do you have a ref? I

've encountered the hypotheses you outlined, but I never been able to find the supporting studies. There's a few generic antioxidant studies, and I found some unsourced reports of an in vitro study, but that's it.

On the other hand there's a whole bunch supporting a protective effect for some cancers.

[Cuddles]

My theory is a bit different. Vitamin C is highly commoditized and there is an abundant competitive production environment with razor-thin margins. This means it's one of the cheapest vitamins to buy in bulk and has a high markup between wholesale and retail.

But that doesn't explain why vitamin C would be highly commoditised in the first place. The most likely reason for that seems to be as I stated - because it's safe to do so for vitamin C but not for most other vitamins.

The antioxidant vitamins like vitamin C do have a carcinogenic threshold, which means it's not impossible to overdose. But these are large doses over long time periods to increase risk even 1%. Overdose takes serious effort.

Yeah, I was talking more about the obvious short term effects than possible long term ones. Take too much vitamin A and your hair falls out, among other things. Obvious symptoms and easy to prove cause and effect, so no sane company is going to tell people to take massive amounts of it. Take too much vitamin C, on the other hand, and you may or may not have a very slightly increased risk of cancer some time in the future. Still not obvious that it actually does anything, and certainly not possible to attribute any specific ailment to taking too much vitamin C. So companies feel perfectly safe selling and promoting it because there's virtually no chance of anyone falling ill and suing them for it.