Need help debunking Vitamin C megadosing

[fls]

Never said anything remotely like that.

Well, you seemed perplexed as to why a company test an omega-3 margarine when it was promoting an omega-3 margarine.

Never said that either.

Aren't you the one promoting in vitro studies as likely to tell us what will happen in clinical studies?

I rarely read sigs. Again though, poor (and insulting) logic does not become you.

Yeah? Which part is poor logic and why, specifically?

You seem to think the omega-3/margarine study is "adequate", which does nothing more than show you have less than adequate knowledge of the topic.

You were the one who brought up the omega-3 study. It wasn't something I promoted.

It's not that hard Linda. I even quoted you directly - "will help". Not "might help" or "probably help" or is "shown to help 80% of people". "will help".

My mother-in-law is currently undergoing cancer treatment. She's had her uterus, ovaries, appendix, and half her colon removed. They're not at all certain where the cancer originated but are working on the basis it's colon cancer.

They think they removed it all.

They are however recommending she undergo chemotherapy. She may not have cancer any more. If she does, the chemo may or may not help. There are serious potential side effects.

We don't know if it will help.

You ask - "Is there a reason to give something a try if we don't have information which tells us it will help"

Yes, there is.

I'm sorry. I wasn't indicating something that specific with the word "will" (it seemed like more of a general term to me, but I apologize if it confused you).

Linda

 

[icerat]

Well, you seemed perplexed as to why a company test an omega-3 margarine when it was promoting an omega-3 margarine.

nope, not perplexed at all. Pretty perplexed that any scientist with knowledge in the field would do it, or accept it, though.

Aren't you the one promoting in vitro studies as likely to tell us what will happen in clinical studies?

nope

Yeah? Which part is poor logic and why, specifically?

"DIM" proponents also probably promote drinking water. Does that make it a bad idea?

You were the one who brought up the omega-3 study. It wasn't something I promoted.

I brought it up as poor research. You have, in your belligerent way, defended it.

I'm sorry. I wasn't indicating something that specific with the word "will" (it seemed like more of a general term to me, but I apologize if it confused you).

Right, so I should instead take the question as -

"Is there a reason to give something a try if we don't have information which tells us it might help"?

No, there isn't, unless it's a last resort. I've not once suggested there is, despite your continued insistence on trying to claim or imply I have.

 

[fls]

"DIM" proponents also probably promote drinking water. Does that make it a bad idea?

Then you didn't understand my explanation.

I brought it up as poor research. You have, in your belligerent way, defended it.

Huh? No I didn't. I just pointed out that your criticisms weren't particularly valid.

Right, so I should instead take the question as -

"Is there a reason to give something a try if we don't have information which tells us it might help"?

No, there isn't, unless it's a last resort. I've not once suggested there is, despite your continued insistence on trying to claim or imply I have.

Huh? You were the one saying that it is worthwhile to take vitamin C in spite of a lack of information which tells us it is any more likely to do something useful than hundreds of other substances we could try. All I suggested is that we don't really want to be wrong almost all of the time by taking inadequate information as our guide - that it would be better to be right more often than we were wrong. Surely there is some reasonable compromise between 100% certainty and a 1% chance of an effect?

Linda

 

[icerat]

Huh? No I didn't. I just pointed out that your criticisms weren't particularly valid.

you've made no real attempt at all to address my criticism of the study

Huh? You were the one saying that it is worthwhile to take vitamin C in spite of a lack of information which tells us it is any more likely to do something useful than hundreds of other substances we could try.[/uote]

I never did any such thing. I suggested it might be worth trying wholly because there's information which suggests it might be useful

All I suggested is that we don't really want to be wrong almost all of the time by taking inadequate information as our guide - that it would be better to be right more often than we were wrong.

Only if your goal is being right, rather than finding something helpful. In the absence of any real risk there is nothing at all wrong with being wrong, not even "almost all of the time", though that's unlikely to happen except in your straw man of doing things "in spite of a lack of information"

 

[icerat]

I have not seen good, relevant research. FLS has been patiently explaining to you why the research you've seen is not good or relevant.

She's done no such thing. All she's done is say "homeopathy comes up with positive results sometimes too". She's not directed any criticism at all at any of the studies I linked to, let alone the many studies I did not.

She has also failed to provide a single study supporting the idea that vitamin C and inflammation are not connected, which is not surprising considering it's very well established.

You are again failing to understand what the studies do and do not say.

So tell me.

You called vitC low risk without qualification. I pointed out that your statement was not accurate.

No you didn't. You pointed out some rare situations where low risk may manifest. You confirmed my point.

It took me just two minutes to find two studies that explored vitC supplementation and concluded risk. One was worried about a risk for diabetics, and they found one. About 8% of the population is diabetic.

And how many of that are also post-menopausal?

But maybe you should have spent more than "just two minutes". I attempted to find all human clinical trials involving Vitamin C and published in the past 15 months (2010/2011). I'm afraid I stopped looking after the first 1000 studies.

Antioxidant Supplementation Does Not Alter Endurance Training Adaptation

Variegate porphyria induces plasma and neutrophil oxidative stress: effects of dietary supplementation with vitamins E and C

The effects of vitamin C supplementation on incident and progressive knee osteoarthritis: a longitudinal study

Age-Related Cataract in a Randomized Trial of Vitamins E and C in Men

The efficacy of high doses of vitamin C in patients with paraquat poisoning

Assessment of Total Antioxidant Capacity and the Use of Vitamin C in the Treatment of Non-Smokers With Chronic Periodontitis

Supplementation of vitamin E, vitamin C, and zinc attenuates oxidative stress in burned children: a randomized, double-blind, placebo-controlled pilot study.

Effects of Vitamin C and E Combination on Element and Oxidative Stress Levels in the Blood of Operative Patients Under Desflurane Anesthesia

Beneficial Effects of Vitamin C and Vitamin E Administration in Severe Head Injury: A Randomized Double-Blind Controlled Trial: 931

An antiinflammatory dietary mix modulates inflammation and oxidative and metabolic stress in overweight men: a nutrigenomics approach

Supplementation with a combination of antioxidants does not affect glycaemic control, oxidative stress or inflammation in type 2 diabetes subjects

Vitamin C provision improves mood in acutely hospitalized patients

Pilot translational study of dietary vitamin C supplementation in Barrett's esophagus

Vitamin C supplementation lowers urinary levels of 4-hydroperoxy-2-nonenal metabolites in humans

Long-Term Intermittent Multiple Micronutrient Supplementation Enhances Hemoglobin and Micronutrient Status More Than Iron + Folic Acid Supplementation in Bangladeshi Rural Adolescent Girls with Nutritional Anemia

Vitamin Supplementation Increases Risk of Subclinical Mastitis in HIV-Infected Women

Effects of Vitamins C and E Combination on Element Levels in Blood of Smoker and Nonsmoker Radiology X-Ray Technicians

Vitamin C And Vitamin E Supplementation In Pregnant Women At Risk For Pre Eclampsia : A Randomized Controlled Trial.

VITAMIN C AND E SUPPLEMENTATION TO PREVENT SPONTANEOUS PRETERM BIRTH

Effects of high-dose B vitamin complex with vitamin C and minerals on subjective mood and performance in healthy males

Effect of long-term treatment with antioxidants (vitamin C, vitamin E, coenzyme Q10 and selenium) on arterial compliance, humoral factors and inflammatory markers in patients with multiple cardiovascular risk factors

Vitamins C and E to Prevent Complications of Pregnancy-Associated Hypertension

Vitamin C and E Supplementation Does Not Reduce the Risk of Superimposed PE in Pregnancy

EFFECT OF TEA POLYPHENOLS AND VITAMIN C INTERVENTION ON PATIENTS WITH HYPERURICEMIA AND DYSLIPIDEMIA

Effect of Vitamin C on Cardiac Performance Following Live Firefighting

The effect of antioxidant supplementation on insulin-sensitivity in response to endurance exercise training

Effects of multivitamin and mineral supplementation on adiposity, energy expenditure and lipid profiles in obese Chinese women

Efficacy of Vitamin E and Vitamin C in the Treatment of Nonalcoholic Steatohepatitis

Vitamin C supplementation in kidney failure: effect on uraemic symptoms

Effects of a multi-vitamin/mineral supplement on cognitive function and fatigue during extended multi-tasking

Of these 30 studies, one found a "risk", an apparent increase in risk of mastitis in a population of HIV+ tanzanian mothers, and another found a side effect - an increase in nausea for patients with kidney failure.

29 of 30 studies found no risk, and many reported benefits.

That's just the past year or so. For some reason you chose to ignore all of them in your assessment of "risk".

Your comment about a study saying the "exact opposite" does not compute. I assume you are referring to the study that should no cardiovascular problems with the non-diabetics.

non-diabetic postmenopausal women you mean

That is not a declaration of safety. The other study only looked at pregnant women at risk for PE. We cannot conclude that women not at risk would be affected differently. It would require further study.

Or it requires more than 2 minutes of googling.

I am simply refuting your claim that vitC supplementation is low risk. We do not actually know if it is or not

Codswallop.

Well ... unless you're an HIV positive post-menopausal Tanzanian pregnant diabetic breast feeding mother. Then we might exceed "low risk".

 

[fls]

you've made no real attempt at all to address my criticism of the study

Well, your criticism seemed to consist of a claim that they had not controlled for a factor which may or may not influence the results and that by not doing so, it was bizarre to even attempt the study. I addressed the claim that factors were left uncontrolled, and the reasoning behind performing efficacy studies.

Huh? You were the one saying that it is worthwhile to take vitamin C in spite of a lack of information which tells us it is any more likely to do something useful than hundreds of other substances we could try.

I never did any such thing. I suggested it might be worth trying wholly because there's information which suggests it might be useful

What are your criteria for "information which suggests it might be useful"? Or what are your criteria for "good" and "relevant"? For example, as I have mentioned, I do not call the kinds of studies whose results only infrequently are confirmed with respect to clinical outcomes "good" (such as in vitro results showing effects against inflammation which only infrequently go on to show results in clinical outcomes that depend upon inflammation). And I don't call outcomes which don't measure any aspect of health "relevant".

Only if your goal is being right, rather than finding something helpful. In the absence of any real risk there is nothing at all wrong with being wrong, not even "almost all of the time", though that's unlikely to happen except in your straw man of doing things "in spite of a lack of information"

Okay, that's worthy of discussion. What are the consequences of following advice which is right at least half the time (or more often than not) vs. advice which is wrong almost all of the time with respect to health outcomes?

Linda

 

[fls]

She's done no such thing. All she's done is say "homeopathy comes up with positive results sometimes too". She's not directed any criticism at all at any of the studies I linked to, let alone the many studies I did not.

I'm curious...what exactly did you think I was directing my criticisms at, if not the studies I was directly referring to in my criticisms?

She has also failed to provide a single study supporting the idea that vitamin C and inflammation are not connected, which is not surprising considering it's very well established.

That's because I have not criticized the idea that vitamin C shows some in vitro and pre-clinical effects with respect to inflammation. There are many substances which show these kinds of effects. What I have criticized is the idea that it can be assumed that effects measured in isolation tell you what happens in the setting of disease where other processes come into play. We have discovered that most of the time, substances given in the hope that an isolated effect will modify a disease process to a non-trivial extent do not modify the process in the way we hoped, the modification is trivial, the modification is harmful, or all sorts of other effects cancel out any beneficial modifications. What I have criticized is that we do not have good information that vitamin C will be any different. And the plethora of studies you offered below only serves to confirm this.

But maybe you should have spent more than "just two minutes". I attempted to find all human clinical trials involving Vitamin C and published in the past 15 months (2010/2011). I'm afraid I stopped looking after the first 1000 studies.

...

Of these 30 studies, one found a "risk", an apparent increase in risk of mastitis in a population of HIV+ tanzanian mothers, and another found a side effect - an increase in nausea for patients with kidney failure.

29 of 30 studies found no risk, and many reported benefits.

That's just the past year or so. For some reason you chose to ignore all of them in your assessment of "risk".

As Sluagh27 already pointed out, your statement is very naive. Those studies did not look for risk and so they are not capable of telling us whether or not there are risks associated with vitamin C use (therapeutic or otherwise). Some risk would only be found if it happened to have a negative impact on the few outcomes measured.

This is a very important point. You keep insisting on trying to answer questions about vitamin C use by referring to studies which are not capable of answering those questions.

Linda

 

[icerat]

Oh good grief. Slaugh27 presented 2 studies. One of which set out to look for risk, one of which didn't, and claimed that as evidence of risk. Funny how the second study wasn't pointed out as "not capable of answering those questions"

And the other was talking about an extremely small subset of people, but again, funny how there's no mention of external validity there!

But perfectly OK to use those two studies to support the idea Vitamin C is risky for the average person.

Seriously - look in a mirror

What I have criticized is that we do not have good information that vitamin C will be any different

And what did I say right back at the beginning of this thread? And again numerous times throughout it? There's not enough good research

I stand by what I said about that, and I stand by the following -

1. There's a lot of research indicating a role for vitamin C in mediation of inflammation
2. There's a lot of research indicating a role for inflammation in the symptoms of allergic rhinitus, perhaps even the cause
3. There's some clinical research supporting a beneficial effect of vitamin C on related inflammation and as an antihistimine
4. There's been little direct research on treating allergic rhinitis or it's symptoms with vitamin C. One 1991 randomized controlled study found a significant benefit
5. Vitamin C is low risk (note: not megadoses, which I stated from the start is not supported)

So if you've got allergic rhinitus, why the hell not give it a go, the research indicates it might help.

Clearly, in this discussion, you two have little interest in anything more than bombastic pedanticism. At least slaugh27 admits it. But you've exhausted me, so I bow out.

 

[fls]

Oh good grief. Slaugh27 presented 2 studies. One of which set out to look for risk, one of which didn't, and claimed that as evidence of risk. Funny how the second study wasn't pointed out as "not capable of answering those questions"

Because power analyses do not apply to studies with positive findings. That's why.

And the other was talking about an extremely small subset of people, but again, funny how there's no mention of external validity there!

But perfectly OK to use those two studies to support the idea Vitamin C is risky for the average person.

Again you are missing the point. If you start, as you do, by assuming that it is safe and it is effective, you will be wrong most of the time. And one could guess that being wrong most of the time will not benefit health. The studies were used to point out that evidence of harm can be found in the use of substances assumed to be safe, so assumptions of safety are premature.

Seriously - look in a mirror

And what did I say right back at the beginning of this thread? And again numerous times throughout it? There's not enough good research

Right, but your next statement is "use it anyway".

I stand by what I said about that, and I stand by the following -

1. There's a lot of research indicating a role for vitamin C in mediation of inflammation
2. There's a lot of research indicating a role for inflammation in the symptoms of allergic rhinitus, perhaps even the cause
3. There's some clinical research supporting a beneficial effect of vitamin C on related inflammation and as an antihistamine
4. There's been little direct research on treating allergic rhinitis or it's symptoms with vitamin C. One 1991 randomized controlled study found a significant benefit

Copious research shows that preclinical information and non-peer-reviewed letters are incapable of telling us whether a substance will show efficacy, making points 1 to 4 irrelevant.

5. Vitamin C is low risk (note: not megadoses, which I stated from the start is not supported)

So if you've got allergic rhinitus, why the hell not give it a go, the research indicates it might help.

The research indicates it almost certainly won't help, so your "might" is some small "p-value". Did you not notice that the plethora of studies you referenced were negative with respect to efficacy?

Linda

 

[Emet]

The research indicates it almost certainly won't help, so your "might" is some small "p-value". Did you not notice that the plethora of studies you referenced were negative with respect to efficacy?
Linda

If nothing else, I learned a lot about reading and interpreting published papers.

Thanks, Linda.

 

[icerat]

If nothing else, I learned a lot about reading and interpreting published papers.

Thanks, Linda.

you learned how not to use science

The studies were used to point out that evidence of harm can be found in the use of substances assumed to be safe, so assumptions of safety are premature.

There have likely been thousands of studies involving vitamin C. A tiny percentage have detected negative outcomes - fewer than you would expect by chance alone! The vast vast majority reported no negative outcomes.

Yet you dimiss this purely because the majority of them were looking for positive effects and not negative effects and it is thus pedantically correct to do so. It does not however reflect reality. It's that type of bombastic pedanticism that gives skepticism a bad name. Fortunately most scientists don't subscribe to it.

Right, but your next statement is "use it anyway".

No. It's try it anyway. A difference. If you get no benefit, don't continue.

Copious research shows that preclinical information and non-peer-reviewed letters are incapable of telling us whether a substance will show efficacy, making points 1 to 4 irrelevant.

Utter rubbish. They're incapable of conclusive evidence yes, but they certainly provide evidence. That's why they're done in the first place and why they lead to clinical trials. If they were irrrelevant they wouldn't. You seem to conveniently ignore the fact that substances that don't pass pre-clinicals rarely proceed to clinical trials.

Did you not notice that the plethora of studies you referenced were negative with respect to efficacy?

I don't know if you're being deliberately dishonest, lazy, or both. Either way you apparently assumed said I said I would "bow out" you could get away with this claim.

Did you notice that one of the studies I listed wasn't even a clinical trial? An error on my part, but it now shows you didn't put much effort in to reviewing the studies.

A quick back of the envelope calculates that of the 29 remaining studies, 17 found a positive effect, 11 found no effect and 1 was negative.

Now I'm done. You clearly have no interest in anything but arguing, but you'll undoubtedly come up with some superficially appealing response.

 

[Emet]

you learned how not to use science

Please don't presume to tell me what I've learned. Thanks.

But you've exhausted me, so I bow out.

I'm done. You clearly have no interest in anything but arguing.

Encore?

 

[fls]

There have likely been thousands of studies involving vitamin C. A tiny percentage have detected negative outcomes - fewer than you would expect by chance alone! The vast vast majority reported no negative outcomes.

You misunderstand. You are referring to looking for evidence for a positive effect and finding a negative effect instead. This is not what is meant by a study of safety. The other problem is that studies looking for an effect are not designed to discover harm, in that 'no harm' is really an attempt to confirm the null hypothesis with confidence. This means the confidence is measured by the power of the study, rather than by the p-value.

No. It's try it anyway. A difference. If you get no benefit, don't continue.

Unfortunately, this is no better. Taking something for a condition which waxes and wanes, like allergic rhinitis, doesn't tell you if it was the effect of the substance when it wanes. This kind of thinking is why people believe homeopathy works and why we thought blood-letting helped for hundreds of years. And it's useless for some of your other recommended uses, like Alzheimer's prevention, since there isn't any benefit to feel.

Utter rubbish. They're incapable of conclusive evidence yes, but they certainly provide evidence. That's why they're done in the first place and why they lead to clinical trials. If they were irrrelevant they wouldn't. You seem to conveniently ignore the fact that substances that don't pass pre-clinicals rarely proceed to clinical trials.

I addressed that in my first post. The only reasonably reliable and valid way to show efficacy is through clinical trials (and all-or-none studies which aren't applicable here). But we can't do these trials on every substance (I hope the reasons are obvious). So we try to exclude some substances we don't have to try beforehand and that's what in vitro and pre-clinical trials do for us - they remove a bunch of ineffective substances from further consideration. But it doesn't mean that what's left has much hope for success. It just means that we can apply our more strict test to a smaller number of trials.

I don't know if you're being deliberately dishonest, lazy, or both. Either way you apparently assumed said I said I would "bow out" you could get away with this claim.

Fortunately the evidence shows that claims of bowing out have little predictive power.

Did you notice that one of the studies I listed wasn't even a clinical trial? An error on my part, but it now shows you didn't put much effort in to reviewing the studies.

I noticed that quite a few of your references weren't clinical trials. But I didn't bring it up, since it wasn't relevant and I didn't want to be accused of being pedantic by doing so (a situation where the accusation would be somewhat a propos).

A quick back of the envelope calculates that of the 29 remaining studies, 17 found a positive effect, 11 found no effect and 1 was negative.

If you like, I can go through each study in a little more detail. You missed that quite a few weren't clinical trials (not just one). You also missed that many of those you are counting as positive were actually negative studies reported as though they were positive (a seemingly common DIM method). And of course, some of them are merely studies on correcting vitamin deficiencies or test substances with multiple components, so they aren't tests of vitamin C's potentially therapeutic effect. Going through them in detail for you (and by, you, I mean anyone who is interested in interpreting published papers) will have to wait until I am off the road though.

Linda

 

[Emet]

If you like, I can go through each study in a little more detail. You missed that quite a few weren't clinical trials (not just one). You also missed that many of those you are counting as positive were actually negative studies reported as though they were positive (a seemingly common DIM method). And of course, some of them are merely studies on correcting vitamin deficiencies or test substances with multiple components, so they aren't tests of vitamin C's potentially therapeutic effect. Going through them in detail for you (and by, you, I mean anyone who is interested in interpreting published papers) will have to wait until I am off the road though.
Linda

1. Please buckle up and watch for wildlife in the road.
2. It's entirely up to you, but I for one, would welcome further exploration of the papers cited. It helps put the E in JREF, as they say...
3. Many members post studies all the time. Often it is only the abstract. I doubt I'm the only member who lacks the expertise to interpret the studies, but I may be one of the few willing to admit it.

 

[fls]

Did you notice that one of the studies I listed wasn't even a clinical trial? An error on my part, but it now shows you didn't put much effort in to reviewing the studies.

I noticed several that were not clinical trials. For the sake of interest, I have gone through the studies and categorized each in terms of whether it was a clinical trial, the outcomes measured were relevant to efficacy, the result was positive, the result could reasonably be attributed to efficacy of vitamin C (most studies gave mixed supplements), and if it was directed at correcting deficiencies.

Four of the studies were not randomized, controlled trials, and one study did not have a placebo control.

A quick back of the envelope calculates that of the 29 remaining studies, 17 found a positive effect, 11 found no effect and 1 was negative.

Of the remaining 26 studies, 17 showed no effect (although 6 are reported as though they showed an effect), 8 showed effect and 1 showed harm.

Of the 8 that showed an effect, 2 were correcting deficiencies, 1 did not involve outcomes even remotely related to efficacy, and 5 involved mixtures of many substances of which vitamin C was one part (so that efficacy could not be applied to any one part).

So none of the 30 studies show that vitamin C supplementation has efficacy beyond correcting vitamin C deficiencies. And all 15 studies where one could draw conclusions about the efficacy of vitamin C (RCT, outcome measured efficacy, vitamin C tested alone or no effect shown in mixed interventions) showed that it did not have an effect.

An example of a negative study reported as though there was an effect would be the study on the head trauma (http://journals.lww.com/neurosurger...al_Effects_of_Vitamin_C_and_Vitamin_E.96.aspx). Vitamin C or vitamin E or placebo were given. There were differences in outcomes between the vitamin E and placebo group, but not between the vitamin C and placebo group. There were numerous secondary measures taken which were of little to no clinical relevance and vitamin C showed a difference on one of those measures. Testing multiple relationships post hoc should elicit several 'statistically significant' findings due to chance, so this doesn't have any evidentiary meaning.

Linda

 

[Emet]

Thanks, Linda.