“Manufacturing Doubt”: Sir Cliff Richard weighs in on the Cochrane review.
Ben Goldacre
The Guardian,
Saturday April 26 2008
And so our ongoing project to learn about evidence through nonsense enters its sixth improbable year. This week, the assembled celebrity community and vitamin pill industry will walk us through the pitfalls of reading through a systematic review and meta-analysis from the Cochrane Collaboration, an international not for profit organisation set up 15 years ago to create transparent, systematic, unbiased reviews of the medical literature on everything from drugs, through surgery, to community interventions. Last week Cochrane produced a comprehensive, gold standard review, looking at 67 trials describing the experiences of 230,000 people, which showed that antioxidant vitamin pills do not reduce deaths, and in fact may increase your chance of dying. [Summary here, full document here, plain language summary on page 2].
In the Health Food Manufacturers Association press release, both Gloria Hunniford and Sir Cliff Richard issued their own definitive refutations. Carole Caplin explained: “It must be obvious to everyone who hasn’t got a vested interest in supplements that this review is absolute rubbish, it contains fundamental flaws.” In a press release issued on behalf of the food supplement industry. Criticising an academic collaboration which does not accept any corporate funding.
So what were these flaws? The entire pill community were worried by the way that trials were selected for inclusion in the group analysis. Dr Rajendra Sharma, ex-head of the Harley Street-ish Hale Clinic – a man who advertises his use of a “bioresonance” machine called the Quantum Xrroid Consciousness Interface to diagnose his patients – explained science to the nation on More4 News. “The writers of this study started with 16,000 studies, and we’re asking the question why did it go down to 68, clearly there’s a bias that we’re not yet quite sure about.”
Let the mystery be revealed. The answer to his question can be found in figure 1 on page 156 of the Cochrane report (which of course he read). Of the 16,111 studies which the Cochrane authors found - by using various search terms in various databases - 12,703 were duplicates, 983 were in children and so not applicable to this review’s predescribed remit, and so on.
Carole Caplin picks up the ball. “With nearly 750 studies to choose from, why did the researchers manage to focus on just 67? That’s less than nine per cent of the total number of clinical trials on antioxidants available.” Well, Carole. Many of those trials were excluded simply because they were not the type of trials being looked at in the study – in accordance with the standard protocol for Cochrane reviews - but 400 trials were excluded because there were no deaths in them. This Cochrane review was a study of deaths, comparing deaths on antioxidant pills to deaths on placebo pills. You need deaths to be reported to put a trial in such an analysis.
These deathless trials were mostly small and brief, representing only 40,000 people in total (page 5, kids). But in any case, as a precaution, the Cochrane authors did a re-analysis of their 230,000 people data, adding in hypothetical fake data, for the 40,000 people, with one death in each of the vitamin and placebo groups: it made no difference. Carole may have skipped that part of the 191 page Cochrane report which she read in full and understood [it’s on page 7].
“This isn’t even a new study,” continues Caplin: “it’s simply a re-hash of old work which was widely criticised in 2007 for its inaccuracies.” Interesting point, Carole. This was indeed a reworking of an earlier review published in the journal JAMA, but updated, and in the format required by Cochrane, resulting in a report about 10 times longer than the original journal article. I should hope it did incorporate criticisms from previous work in the same area: this is the whole point of publishing papers, and opening them to informed criticism.
A key question with all research is how to apply it in practice. Are the interventions in the study comparable to the decisions in your real life? “The analysis largely focused on extraordinarily and atypically high doses of antioxidant vitamins,” explained David Adams of the HFMA: “Supplement users would have some trouble trying to replicate this kind of daily intake.”
Well, not that much trouble. I went to Holland and Barrett. In the Cochrane review, the mean dose of betacarotene was 18mg: H&B sell 100 capsules of 15mg betacarotene for £7.49. So practically identical, then. The mean dose of vitamin E was 570 IU: H&B sell 100 capsules of 1000IU – twice that dose - for £19.99. Perhaps David Adams thought nobody would check.
But my favourite insight comes from the actress Jenny Seagrove, and it is a valid one. “I’m not going to be bullied by this dismal research paper - I am 100% confident that the vitamins and mineral supplements I use are safe and effective and I will continue to use them when I choose.” This is the key move. Do you put evidence into practice? Yes: not as an automaton, but at your discretion, taking into account not just the best possible evidence, but also the individuals’ preferences. That is the core of evidence based practice, so munch away, Jenny, and good luck to you. But the publics’ understanding of evidence is far more important than your vitamin pills, so show a little consideration.
· Please send your examples of bad science to bad.science@guardian.co.uk
References:
Mostly in the text above, but because they’re important…
Here is the silly HFMA press release:
www.responsesource.com/releases/rel_display.php?relid=38309&hilite=
Here is the Cochrane review:
mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD007176/pdf_fs.html
Here is the definitive early document on the nature of evidence based practice:
www.bmj.com/cgi/content/full/312/7023/71
And here is a video of Sir Cliff Richard. I think I was just slightly sick in the back of my throat.
.
.
Manufacturing Doubt:
The “contriversy” over this Cochrane meta-analysis has been well covered elsewhere, including DrAust, Holfordwatch, Holfordmyths, Quackometer and more.
In many ways what I found most striking were the similarities between the dissembling of the $60bn food supplement pill industry in this case, and the well established strategy of “manufacturing doubt”, first seen in the tobacco lobby’s war with epidemiology over 40 years ago.
The history of this corporate strategy is very well covered in David Michaels’ new book, Doubt is Their Product: How Industry’s Assault on Science Threatens Your Health, on which there is an excellent essay here.
The sabotage of science is now a routine part of American politics. The same corporate strategy of bombarding the courts and regulatory agencies with a barrage of dubious scientific information has been tried on innumerable occasions — and it has nearly always worked, at least for a time. Tobacco. Asbestos. Lead. Vinyl chloride. Chromium. Formaldehyde. Arsenic. Atrazine. Benzene. Beryllium. Mercury. Vioxx. And on and on. In battles over regulating these and many other dangerous substances, money has bought science, and then science — or, more precisely, artificially exaggerated uncertainty about scientific findings — has greatly delayed action to protect public and worker safety. And in many cases, people have died.
Tobacco companies perfected the ruse, which was later copycatted by other polluting or health-endangering industries. One tobacco executive was even dumb enough to write it down in 1969. “Doubt is our product,” reads the infamous memo, “since it is the best means of competing with the ‘body of fact’ that exists in the minds of the general public. It is also the means of establishing a controversy.”
Nebbish said,
April 26, 2008 at 1:02 am
Six years? Congratulations, and celebrations [all together now…]
But seriously folks, well done, you’re doing good work. Here’s to the next six. And the publication of your book…
CS2TOF said,
April 26, 2008 at 5:23 am
Ben,
Great site - with the right balance of deep thought and levity.
One comment - you should no longer consider “manufacturing doubt” as just a corporate strategy. It is used equally by citizen’s groups (who, for example, argue that fluoride in the water is totally ‘unsafe’), as it is by many governments (who argue with equal fervor that fluoride is absolutely essential for the nation’s teeth).
Until we all recognize that “safe” is a relative and not an absolute term (like “tall” - a building can only be taller and/or safer than another), then the real goal, which is enjoying one’s life experiences through judicious decisions based on well-estimated probabilities, remains elusive.
monkeychicken said,
April 26, 2008 at 8:29 am
People (the celebrities) straying outside of their sphere of competence is always anger inducing.
Unfortunately it happens everywhere. I work in the nuclear industry and when it happens there, it can be really scarey.
Am I the only one who seems to spend their entire life angry?
R N B said,
April 26, 2008 at 10:52 am
The criticism was
“in a press release issued on behalf of the food supplement industry. Criticising an academic collaboration which does not accept any corporate funding.”
Enough said.
SportsFan said,
April 26, 2008 at 11:02 am
Interesting article as always.
The science here is pretty difficult to dispute. The only only thing I would say is that personally I don’t take vitamins to extend my life. I could get hit by a bus tomorrow and they wouldn’t help me much there. I take vitamins because I have an active lifestyle doing a bit of bodybuilding and a bit of martial arts. Being in my mid forties I feel I need all the help I can get. I’m looking to be fitter now rather than longevity. The received wisdom is that vitamins are the thing.
Now I’m not completely stupid. I have a reasonably strong suspicion that I am wasting my money, but I don’t want to risk being wrong about that! It is clearly impossible to carry out tests using myself as a subject and have the results mean anything.
What I would like to see is a review of this nature into whether the use of vitamins is beneficial to the physical performance of active individuals. I’d be more than happy to stop if the received wisdom was shown to be wrong. And I’d save money too.
And while they’re at it I’d like to see a similar review of protein supplements as used by strength athletes - just to settle a dispute I once had with a doctor.
Well done Ben for six years of this. You’ve made me re-examine a few beliefs and for that I thank you. Keep it up.
used to be jdc said,
April 26, 2008 at 11:10 am
So does David Adams of the HFMA think that it’s only the ‘atypically high doses of antioxidant vitamins’ that are bad?
Is this the same David Adams that was campaigning to keep higher dose supplements?
“The director of the U.K.-based Health Food Manufacturers’ Association (HFMA), David Adams, is petitioning British Prime Minister Tony Blair to change legislation banning high-dose vitamin supplements, and CNN reports that Adams is representative of 140 health food firms worldwide who are angry at the European Union ban.” http://www.naturalnews.com/010086.html
Also there’s this from a HFMA Position Paper on Beta Carotene:
The HFMA decided that “a dietary supplement containing a modest amount of beta-carotene (5–10 mg/day) may be prudent for health and well-being.” PDF here: http://www.hfma.co.uk/PositionPaperBetaCarotene.pdf
ACH said,
April 26, 2008 at 3:47 pm
Sportsfan - “received wisdom” Received from who? People who are selling you supplements? Dieticians - who are qualified to advise on diet & lifestyle - will tell you that eating a balnced diet gives you sufficient vitamins to be healthy, or at the most, a simple 1 a day multivitamin is sufficient.
evidencebasedeating said,
April 26, 2008 at 4:34 pm
Only 6 years, Ben?
You young johnny-come-lately whippersnapper.
How dare you contest the accumulated perceived wisdom of, ooh, well over a century of pillpopping from four z-list celebs who possess ne’er a single science qualification amongst them.
You - as a media doc mired in science - do not understand the whimsical and deluded righteousness of Those-Who-Don’t-Eat (of the genre anorexia/ eating disorders/body image issues/ weird healh beliefs) who are prettily pampered by the objective, impartial, ethical and moral industry that Sells Supplements To The Uninformed and The Exploitable.
Shame On You!!
emmer said,
April 26, 2008 at 4:42 pm
Really excellent article today - thanks!
SportsFan said,
April 26, 2008 at 6:02 pm
ACH - Yeah I pretty much agree - hence my dilemma. In recent years I have settled on the one-a-day multvitamin approach as you have suggested. I’m still left wondering though if there is any science recommending any other approach for those active sporty types. Most of the serious nutritional advice we get get appears to be aimed at the average couch potato and I’m yet to be convinced that it applies equally across the board. It is well accepted in weight-training/ bodybuilding circles that you won’t get anywhere without correct diet and I believe that the same applies for most strenuous activity or sport. But then most of the advice comes from magazines sponsored by sports nutrition companies. I’d like science to put some parameters around the area of supplements in sports nuttrition, but then who would pay for it? And with so many real problems to solve why should science bother?
evidencebasedeating said,
April 26, 2008 at 6:51 pm
Sportsfan -
suggest if you’re serious about nutrition for exercise you check out the advice of a sports-accredited dietitian - find a local one at http://www.nutritionsociety.org.uk/senr/ and select ‘Dietitian’ from the specialism choice.
Their official site at www.disen.org seems to be having server problems at the mo…
choosing a dietitian should mean you only take the supplements you need to for your particular exercise needs.
Daibhid C said,
April 26, 2008 at 8:03 pm
Ye gods, is *anyone* still listening to Carol Caplin? About *anything*? Did Cheri Blair’s credibility die for nothing?
Cliff Richard, OTOH, hasn’t aged for thirty years so he must know *something* the rest of us don’t…
Ben Goldacre said,
April 26, 2008 at 8:35 pm
Cliff Richard, OTOH, hasn’t aged for thirty years so he must know *something* the rest of us don’t…
william burroughs looked pretty good until he died well into his eighties. perhaps someone should start advocating a scag diet.
Dave Gould said,
April 26, 2008 at 10:56 pm
Yes, can’t find any flaws in the study and thanks for covering it, Ben.
The only question mark for me is that 81% of studies were sponsored by pharmaceutical companies, notorious for burying studies which don’t support their agenda. What is Big Pharma’s agenda wrt megadose vitamins?
I was surprised at the extensive media coverage of negative reaction to this study.
It would be wrong however to assume that Cliff, Carol et al do not receive health benefits. They benefit from the inherent placebo effect - so forgive them for defending that.
Ben Goldacre said,
April 26, 2008 at 11:51 pm
yes, that’s one of many things which are so similar between the pharmaceutical pill industry and the vitamin pill industry… they’re one and the same, in behaviour and in financial terms.
just a few examples.
BioCare, the vitamin pill company Patrick Holford works for - and received £500,000 from in 2007 - is 30% owned by Elder Pharmaceuticals.
Seven Seas vitamin co is a wholly owned subsidiary of pharmaceutical company Merck (revenue $22bn).
Roche ($28bn) and Boehringer Ingelheim ($10bn) have large longstanding holdings in the vitamin pill sector.
The standalone ones arent small companies either. NBTY, the company behind Solgar and Holland & Barrett has annual revenue of around $2bn alone.
And of course Scottish food supplement pill company Efamol were at the centre of one of the most legendary withheld data stories of all time, around the evening primrose oil scam:
http://bmj.bmjjournals.com/cgi/content/full/bmj;327/7428/1358
This is a very big industry, and it has behaved in some elaborate and rather bizarre ways in reaction to criticism, which will reflect rather badly on it in time. But more on that later.
Dr Aust said,
April 26, 2008 at 11:53 pm
Cliff Richard, I suspect, has many things that often help rich people to look “well preserved”:
1. Bags of money
2. Flunkies to do most things for him that ordinary mortals have to do themselves
3. His own tennis court, gym, swimming pool, chef etc etc
4. A top-notch cosmetic surgeon who does discreet and subtle work
5. Botox
..anyone got any more suggestions? I was also tempted to add “no children”
don_pedro said,
April 27, 2008 at 2:47 am
Dr Aust wrote:
..anyone got any more suggestions?
A portrait of the man, kept locked in the attic, relecting the wear and tear of sustained and depraved debauchery, so that he doesn’t have to.
superburger said,
April 27, 2008 at 8:26 am
ben, i hope you thought long and hard before writing negatively about National Treasure Cliff Richard.
Millions of menopausal women, on hallucinogenic levels of HRT will be after you.
SportsFan, if you are into running, then you should get a copy of “The Lore of Running” by tim noakes (who is/was a south african medic)
there’s a good section on supplements (both legal and illegal) in sport - based on hard evidence and the general conclusion is that as long as you are eating a generally healthy diet then most pills and potions are pointless.
another good argument is that hard, structured training can increase raw speed by >25%, but more importantly endurance (i.e. ability to maintain higher speeds) can increase by 1000s of %. - and the results are easy to measure. No supplement (including illegal ones) can produce these benefits, so for ‘non-elite’ runners good quality training is the number 1 ’supplement’ but obviously, running 50,60,70 miles a week to improve a marathon time is less attractive than chewing some vitamins.
In elite athletes (who have presumably trained to their maximum potential) the %ges they are looking to shave are
gimpyblog said,
April 27, 2008 at 8:49 am
Both Iggy Pop and Keith Richards seem to have done OK by following that route.
ACH said,
April 27, 2008 at 9:56 am
“BioCare, the vitamin pill company Patrick Holford works for - and received £500,000 from in 2007 - is 30% owned by Elder Pharmaceuticals.”
Didn’t Holford say (on the infamous Radio 5 admission of more vested interest than Dr Gluud) that he got about a fifth of a drug rep’s salary from Biocare?
Can someone please direct me to the pharma company that pays its reps £2.5 million. And a reference for a job with them!
Jellytussle said,
April 27, 2008 at 10:23 am
”
But more on that later.
#
Dr Aust said,
April 26, 2008 at 11:53 pm
Cliff Richard, I suspect, has many things that often help rich people to look “well preserved”:
1. Bags of money
2. Flunkies to do most things for him that ordinary mortals have to do themselves
3. His own tennis court, gym, swimming pool, chef etc etc
4. A top-notch cosmetic surgeon who does discreet and subtle work
5. Botox
..anyone got any more suggestions? I was also tempted to add “no children”
#
don_pedro said,
April 27, 2008 at 2:47 am
Dr Aust wrote:
..anyone got any more suggestions?
A portrait of the man, kept locked in the attic, relecting the wear and tear of sustained and depraved debauchery, so that he doesn’t have to.”
I can confirm that this is true. It is a picture of Keith Richards.
Robert Carnegie said,
April 27, 2008 at 5:14 pm
I don’t understand the point that “400 trials were excluded because there were no deaths in them.” I may as well cast the question naively as try to express the precise nature of my concern, so: doesn’t picking only trials in which people die create a bias in which the therapy on trial appears to be associated with deaths?
I suppose also that it could be conceivably that antioxidants improve the quality of life whilst not making it less likely to end during a trial period, or even more likely. For instance if the pill cures your disease but itself may kill you. Perhaps that is covered by combining trials of healthy people and trials specifically of the sick.
Finally, what does “Harley Street-ish” mean, is it like off-Broadway, and where in the world do you find people to be impressed by a “Quantum Xrroid Consciousness Interface” instead of running, or hobbling, a metric mile upon hearing of the thing?
Dr Aust said,
April 27, 2008 at 8:06 pm
Robert, re the trials with no deaths being excluded, we had a discn about this over at Holfordwatch here.
The basic point is that they mean that they excluded trials where there were no deaths in either the control or the supplement patient groups. If you are measuring and comparing death rate you need enough deaths to measure.
perspix said,
April 27, 2008 at 8:39 pm
Robert C: I think “Xrroid” is an abbreviation of “haemorrhoid” so perhaps the Quantum Xrroid Consciousness Interface thingy is a device for connecting your mind to the consciousness of your arse-grapes.
Dave Gould said,
April 28, 2008 at 12:07 am
The study authors believe that a death in a study does not bias the study towards or against vitamins.
One could propose the theory that vitamins are bad for most but good for for everyone else.
Another theory would be that people who correctly believed they were going to die both knew they weren’t taking placebo and were much less likely to drop out of the studies. There was a small difference between healthy and disease-based studies that might show this.
The other notable correlation found is that those studies which the authors could verify as being more scientific showed an even worse result for vitamins.
Furthermore, the authors included 4 studies without placebo controls and still couldn’t find a benefit.
The increased mortality rate is so small that it’s not worth paying attention to.
What hard to dispute here is that if megadose vitamins make the general population live longer, it’s so tiny as for that effect to be discounted.
Mind you, the same can be said for nearly all medications.
Robert Carnegie said,
April 28, 2008 at 1:37 am
Yes… are we saying that zero isn’t a measurement? I’ll look at HolfordWatch. …On second thoughts, that’s very wordy, I see. Perhaps I’ll abide in ignorance.
If there are studies that didn’t keep count of people who did die, that’s… surprising.
Moganero said,
April 28, 2008 at 10:18 am
A bit off topic, but I noticed that Holland and Barrett in Hanley, Stoke-on-Trent still has stickers on their shelves showing _Dr_ Gillian McKeith recommended some of their products. They didn’t seem to be in the slightest bit bothered when I mentioned it to them, but then maybe it helps them sell more.
CDavis said,
April 28, 2008 at 1:32 pm
You and Cochrane et al neglected to mention it, but no doubt you’ll make an exception for raw glucose - 20,000 Lucozade drinkers can’t be wrong, can they?
Sporty types need ‘energy’ - so *they* drink it, apparently. Therefore millions of couch-potatoes who wish they could look like sporty types drink it too, by the gigacalorie. Stands to reason.
CD
Jamie Horder said,
April 28, 2008 at 1:49 pm
Robert : Zero is a measurement, but if you find that there are zero deaths in both the people who get vitamins, and the people who get placebo, this doesn’t really tell you very much. In particular it means that you can’t tell whether the vitamins reduce deaths, because you can’t go lower than zero. So including these trials could actually make the analysis biased against vitamins…
used to be jdc said,
April 28, 2008 at 4:37 pm
Heh. The ANH has a shockingly bad press release on the Bjelakovic study which ends with an accusation framed as a question (hm, weaselly) - PDF.
The insinuation is that the Cochrane collaboration is ‘under the influence of drug companies’ - which is really quite amusing given that one of the writers of the press release defending supplements was (at least until recently) employed by a firm selling food supplements (Ultralife). The other writer was working at Nutrition Associates Ltd - who offer medical advice and treatments based on nutrition and allergy principles, which can mean recommending tests using, e.g., Great Smokies Diagnostic Laboratory and YorkTest.
Dr Aust said,
April 28, 2008 at 5:52 pm
The authors actually explain how they INCLUDED several studies in which death rate was reported AND was zero in ONE group (which could be either controls, or the vitamin-takers, as no upfront assumptions were made). That is, these studies WERE included, contrary to what all the vitamin industry PR flacks and celeb-idiots have been wheeled out to try to tell you.
Zero in BOTH groups gives you NO information from which you can estimate the DIFFERENCE in mortality rate plus/minus supplements in the “populations” from which the study group are derived. All you can say is “overall death rate in the underlying populations from which these groups were derived probably can’t be greater than x%, as if it were bigger than this we would expect to have seen some deaths in a study this size”.
This is the other side of what the stats people call “power calculations”. The studies w no death rates in either group are,as the stats lot say, “underpowered” for telling you anything useful about death rates, though they may have recorded other “outcome measures”.
Squander Two said,
April 29, 2008 at 11:52 am
Dr Aust,
> ..anyone got any more suggestions?
Yep: he’s a singer. Regular exercising of facial muscles tends to keep the face a bit younger-looking. See also Tina Turner. Or compare Page to Plant. And ignore Mick Jagger.
evidencebasedeating said,
April 29, 2008 at 11:04 pm
hmmmmmm
plant mmmmmmmmmmmmmmm
mmmmmmmmmm
Mister Jones said,
April 30, 2008 at 5:36 pm
Love to take apart one of those QUANTUM XRROID CONCIOUSNESS INTERFACE QXCI boxes to see what’s really inside.
http://www.bio-resonance.com/qxci.htm
Craig said,
May 1, 2008 at 5:44 am
The repeated conclusions of reputable vitamin supplement studies appear to be along the lines of “so long as you’re eating a balanced diet, don’t bother…”
However: I don’t eat a balanced diet.
Partly that’s because I do a lot of bushwalking and long-haul motorcycle touring (where I’m surviving on either instant noodles or dodgy roadhouse food for extended periods), but it’s also partly ‘cos I’m a geeky science student who drinks too much, smokes too much and routinely forgets to eat.
So: given that I don’t have a nutritionally great diet, and that’s unlikely to change anytime soon, is a daily multivitamin worth the money? Or is it still going to be just providing value-added urine?
used to be jdc said,
May 1, 2008 at 12:30 pm
Maybe ask a dietitian Craig? If you are talking about taking supplements as ‘insurance’, Catherine Collins made a comment about vit supplements here: http://holfordwatch.info/about/#comment-2964 - but I don’t imagine for a moment that a vitamin pill is going to make up for drinking too much, smoking too much and routinely forgetting to eat.
BDA food facts here: http://www.bda.uk.com/Downloads/November04foodfacts.pdf is written by Catherine Collins.
Robert Carnegie said,
May 2, 2008 at 2:42 am
No deaths means quite a high count of people who didn’t die.
How does this pooling work, though? Do well-regulated studies have equal size groups, or different groups? Do you Cochrane them by just adding eveyone together into bigger groups?
Can you program the Dymo label printer currently advertised to print thousands of labels saying “Not a real doctor”, to smuggle into your local shop selling “Dr.” Gillian McKeith products? Bonus if you also make them say “reduced”, because arguably she is. And I think the sell by date may apply.
kiwitranslations said,
May 4, 2008 at 9:46 am
I would like to know what Ben (and everyone else) thinks about the methods and conclusions of Ray Kurzweil and Terry Grossman. They advocate aggressive supplementation, which makes them suspect in the light of this conversation, but they make a big deal about basing it all on hard science, referencing medical studies for every point they make. The former of the two is highly accomplished in his own specialty (not medicine) and the latter is a medical professional. But how good is their science really? Is it bad science?
One other point, saying “just eat a well-balanced diet” really just begs the question: what is “well-balanced?” At the end of the day, whether it comes through conventional food or in the form of pills we still face the question of what quantities of various nutrients result in optimal health (if we are interested in achieving that).
AK5 said,
October 14, 2008 at 1:17 pm
I am a masters student in human nutrition and firmly believe in the effectiveness of SOME supplements, however, i also firmly believe that the results of the review were valid and reliable. This trial however does not confirm that supplements cant have benefits on mortality. It merely shows that some can be dangerous. I have studied the possible reasons for their harmful effects and would like to share some theories. Vitamin E supplements were likely to have increased mortality as the supplements used alpha-tocopherol alone, however, there are other tocopherols that seem to have different beneficial effects on health. However, they rely on the same enzymes for absorption and thus when only one is given in such large doses the others are not absorbed properly. (see study here http://grande.nal.usda.gov/ibids/index.php?mode2=detail&origin=ibids_references&therow=723903)
Therefore, by taking the supplement they are reducing a number of other benefits including anti-inflammatory properties of gamma tocopherol.
Beta Carotene appears to be related with increased mortality primarily in smokers, this may be due to transformation of this antioxidant into a carcinogen when formed with the compounds in smoke. (see http://www.ncbi.nlm.nih.gov/pubmed/10568335)
The findings of vitamin A are also unsurprising as most people have sufficient vit A stores and any excess cannot be stored and can act as a prooxidant.
Therefore, trials involving mixed tocopherol supplementation, beta carotene solely in non-smokers and not with vitamin A seem likely to give more favourable results and I would recommend anyone taking vitamin E to buy a mixed tocopherol form.