Ok, anyone who tries to follow my rambling should read the article. This post easily demonstrates that "I can play this game too" and that their counter-evidence is weak. Rhetorical tricks (and the deliberate use of logical fallacies) are (is) a lot of fun from time to time, but they're not evidence. I'll grant those guys, as expected I liked (some of) their sceptical remarks.
I think this opinion-piece is very enjoyable if you like well-placed logical fallacies and such stuff.
A committee to evaluate the DRI of vitamin D is convened
According to the report’s abstract: “The majority of the findings concerning vitamin D, calcium, or a combination of both nutrients on the different health outcomes were inconsistent.” "...unchallenged claims about vitamin D’s perceived benefits."
Interesting, what a little selection bias can do, isn’t it? Most recent independent reviews and meta-analyses I’ve read, however, state that the evidence is strong enough to support well-sized, interventional trials (eg. in the case of diabetes prevention, hypertension, cardioprotective effects and cancer mortality). "Inconsistent" does not mean the weight of evidence isn’t positive.
Dr. Barry Kramer sounds an early note of caution
Just reiterating the nature of evidence, nothing to see here, really. But wait 25OHD is
a surrogate marker? What the hell? That’s blatantly false; it's just their (so far) unproven hypothesis.
However, there’s something interesting I get out of that paragraph. Medical decision making is reactionary to the core, too reactionary; we’ve seen it in the case of life extension research and we see it again. I think the medical establishement has fallen prey to the omission bias (“the tendency to judge
harmful actions as worse, or less moral, than equally harmful omissions”).
I am not pushing to ignore the nature of evidence, not at all. But I’ve seen my fair share of ethical principles gone wrong in medicine, awfully wrong. Like for instance the Gonzalez cancer trial, which to paraphrase ORAC was the most unethical trial since Tuskegee and which spit into the face of clinical equipoise. Then there’s the principle of “primum non nocere” which often completely obliterates freedom of (patient) choice.
We should caution people to simply keep in mind that manslaughter by neglect is still manslaughter. In fact, sometimes jumping the gun will save more people than waiting.
Researchers affiliated with the Vitamin D Council drive the science on vitamin D
The influence of scientists affiliated or at least supported by the VD council is interesting, but that’s all. Well, unless you suggest a conspiracy theory or severe ethical misconduct by those people. The way this is extolled constitutes a bona fide ad hominem. What I find interesting is that the authors who strongly criticise epidemiology fall prey to one of the basic fallacies of observation. Correlation (people citing eachother or being cited by the council) does not imply causality (does not imply anything on its own actually). Evidently it could be a form of selection bias, if you arrive at a positive conclusion based on your own evidence, whom are you going to cite? (right, people who produced similar research)
”Despite a notable lack of data derived from RCTs…”
Not true at all.There’s merely a lack of data from meaningful, well-sized RCTs, not RCTs in general (big difference). Sure, we need well-sized RCTs, but we have many smaller RCTs.
“We’re giving you high doses of a secosteroid that will adjust your hormonal and immune activity in ways not yet fully understood.”
Well played. If I explained metabolism of any nutrient to someone that way, I could scare anyone. Just imagine how scary fishoil and fish must look in this context or basically any type of food. Run for your life.
Similar could be said about vitamin K which causes thromboembolism. What? I thought VK does not cause “over-clotting”? Sure it doesn’t, but it can normalise a deficiency in clotting factors which would be protective. That, however, would ignore all other effects of VK.
Did our human ancestors really have extremely high levels of vitamin D?
”Dr. Robert Heaney
[hey why not have a shot at poisoning the well and mention his affiliation in the first sentence?], a researcher affiliated with the Vitamin D Council, said…”
”Why then would just a few burns before the age of 20 dramatically increase the risk of skin cancer? Did humans evolve to get skin cancer?”
First, the abstract does not support this statement and the full paper does not mention the word cancer at all. Didn’t those authors just warn against using surrogate outcomes?
And, yes, we evolved to develop cancer, fidelity of DNA repair is well-balanced against real world needs under which we evolved. We were not meant to get old. Therefore we get cancer; a benefit on cancer incidence would be hardly advantageous to naked apes (humans) dying at <30yo.
”At this point, it’s probably safe to say that we simply do not know how much sun early man got.”
Fair enough, but very, very likely more than now.
Dr. Michael Holick speaks on sunscreen and vitamin D
Boys, such dirty tricks are disingenious. I don’t want to see that crap anymore. Downplaying somone'ss publication record?!
[Holick] has authored or co-authored 59 publications appearing in PubMed on vitamin D (26 more than Dr. William Grant, who is second in that category and a frequent co-author)”
Holick has 348 publications indexed in MEDLINE and 253 refer to vitamin D (see for yourself: "Holick MF"[Author] "vitamin D"). I can only guess that they talk about original publications, but they do not explain it in the text – dishonesty par excellence.
Most Xeroderma pigmentosum patients were deficient, I've looked at the study & it's very small. Their calcitriol levels averaged <40pg... Your dishonesty is showing if you ignore world-wide epidemiology showing great seasonal variation (eg. NHANES).
Now a red herring:
A review by Drs. Wolpowitz and Gilchrest states, “There is no evidence that customary sunscreen use causes vitamin D deficiency or insufficiency in otherwise healthy individuals.”
Do you see where I’m coming from? Yes, people fail at applying sun screen, fair enough. Sure it does not cause deficiency, but it definitely reduces cutaneous synthesis, which the authors almost admit (although, they try to tarnish the studies performed on the topic). Note: Dr. Glichrest has been know for her ignorance on Vitamin D (she’s right on the skin cancer thingy, though).
A concession: vitamin D is not for people with granulomatous disease
Correct and completely besides the point, unless they eventually prove their autoimmunity hypothesis.
Dr. Cedric Garland discusses vitamin D and cancer
To put things in perspective, you’d have to consume 20 eggs or four glasses of vitamin D fortified milk a day in order to get 400 IUs of vitamin D.
Red herring, you could as well spend 2 minutes in the sun. Still a red herring.
“There were literally scores, if not hundreds, of observational studies that showed almost beyond reasonable doubt that hormone replacement therapy would prolong women’s lives, if it were given routinely.”
I’m not an expert but I think that is exactly the reason why it was necessary to test the intervention. Because failing to provide benefical treatments leads to death by neglect (real world vs omission bias).
Observational data are “guilty until proven innocent.”
They’re right about Garland’s graph with the skewed Y-axis. I hate such statistical trickery. If presented before health professionals it makes you look stupid. OTOH, I don’t think that Vitamin D was necessary the main culprit, but I’d need to check. 1000mg calcium was more likely the problem in the WHI finding increased rates of kidney stones.
Dr. Reinhold Vieth speaks about safety
Again, they’re right (apparently the article gets better from paragraph to paragraph). Lack of short term toxicity tells us nada, niente & nill about chronic exposure. Therefore we need well-sized RCTs, but the risk:benefit ratio is in favour of VD. And, hey, we're getting those RCTs!
They may be wrong about the calcitriol being the only active form. According to this review 25OHD binds to the VDR, but it's not sure what the effect of binding is (to me at least).
Dusso AS, Brown AJ, Slatopolsky E. Vitamin D. Am J Physiol Renal Physiol. 2005;
25-D vs. 1,25-D and the long elusive search for biological plausibility
”It seems prudent then, that if a study measures 25-D levels, it should measure 1,25-D levels as well.” Yes.
”Thus, we would venture to say that studies absent levels of 1,25-D should at least be regarded with less rigor than those studies that test both metabolites.” No.
”Is this what passes for biological plausibility among pro-vitamin D researchers?” & related paragraphs constitute one heck of a straw man. There’s a myriad of mechanisms by which vitamin D could act (yes, vitamin D meaning calcitriol or calcidiol). Heck, even I know some of them, although, I never looked much into vitamin D mechanisms (I prefer to look at clinical evdience). MMP-Inhibition, cell cycle progression, exp
ression of oncogenes/tumor suppressors. Plausibility is never a problem (other than if you try to peddle homeopathy...), but plausibility ain't enough.
...ok, I'm taking a break. Will finish bashing tomorrow.
Edited by kismet, 01 October 2009 - 03:25 PM.