7 replies to this topic

[OneScrewLoose]

Excuse me if this has already been posted:
http://www.thelancet...0165-7/abstract

So as we know many non-skeletal disease correlate with low levels of 25(OH)D, and the conventional wisdom around here since I joined has been to get levels to at least 40ng/dl, and I have done as such. However, this study suggests we've had our causation backward, that the low levels are simply the result of disease, not the cause, and that there is no causal relationship between 25(OH)D levels and disease prevention.

So this is kind of a big deal considering what seemed to be an insurmountable flood of evidence suggesting the benefits of Vitamin D supplementation in disease prevention.

Thoughts? Does anyone have access to the full text?

Edited by rwac, reason: fixed link.

Edited by rwac, 13 March 2014 - 07:52 AM.

[Dolph]

The problem is the same as with most reviews and metaanalyzes of Vitamin D at the moment. The RCTs that were reviewed here are those that we have at the moment, those with Vitamin D dosages of 400IUs on average that were used to improve bone health. (Although this tiny dose is not even very effective for that indication.) So we are talking about subgroup analyzes here, which are not reliable anyway, and dosages of Vitamin D that do not much if anything to improve 25OHD status. It's just futile to suggest that conclusions can be drawn at that point and a metaanalyzis of worthless RCTs doesn't help.

By the way, although I think the data used is pretty much worthless, me gut feeling is that the hypothesis is correct. Sadly... I think we have to wait for the results of the VITAL trial for a definite answer but I'm not very optimistic at all.

[OneScrewLoose]

Sorry Dolph, I found out what that shiny new "STOP!" button does. Can a mod put his post back?

To respond to what you were saying: this analysis does not use Vitamin D dosages as a way to gauge disease prevention, but a direct measurement of 25(OH)D levels. So the argument that "the dosages were to low" seems to be irrelevant. Seems pretty solid to me.

[Dolph]

As far as I can tell they only looked on the pretreatment 25OHDs. That's worthless if you don't know if the values changed at all on treatment.

Edited by Dolph, 13 March 2014 - 08:53 AM.

[OneScrewLoose]

Can you cite that please? From just the summary they looked at supplementation of a minimum of 50ug(2000IU) and the results were non-existent. That is a common dose around here.

[Kevnzworld]

The pro/con vitamin D debate is one of the oldest reoccurring debates on Longecity. I don't like meta analysis studies. They can be designed to include, not include and weight studies in a way to show almost any result. I could dig up real studies, randomized, placebo controlled,ones, for days that show that higher vitamin D intake and 25 ohd levels are correlated with lower levels of disease occurrence.
In this one, randomized placebo controlled...women were given either placebo, calcium or calcium plus 1100iu vit D. The results show a significantly lower incidence of cancer over a four year period for women taking calcium plu vitamin D vs the other two groups.
" With the use of logistic regression, the unadjusted relative risks (RR) of incident cancer in the Ca + D and Ca-only groups were 0.402 (P = 0.01) and 0.532 (P = 0.06), respectively. When analysis was confined to cancers diagnosed after the first 12 mo, RR for the Ca + D group fell to 0.232 (CI: 0.09, 0.60; P < 0.005) but did not change significantly for the Ca-only group. In multiple logistic regression models, both treatment and serum 25-hydroxyvitamin D concentrations were significant, independent predictors of cancer risk."
http://ajcn.nutritio...85/6/1586.short

[OneScrewLoose]

Yes, that is possible with meta studies. However, it becomes your burden of proof to show that this kind of selectivity has been done in this particular study. The meta study does not deny the correlation between 25(OH)D and instance of disease, but rather suggests that the causation is the reverse of what is commonly assumed. I am not saying that this study is definitive, but it should give us pause about what we consider to be "common knowledge" around here, and cause us to reevaluate the science. If someone wants to really dig into this, I might be able to PM the full text to you if you PM me.

BTW, someone PM'd me saying that they were unable to see the link in the OP. Anyone else having this problem?

[johnross47]

(As a non science person) I have always thought that one of the more telling reasons for going with vit D3 supplementation was the north/south differences in 25OH(D) and the associated differences in disease and mortality. A TED talk posted several other places

https://www.ted.com/..._for_your_heart

might clear up this issue or at least point towards a solution. The talk describes the discovery of the effects of UV on generating NO from stores of nitrates in the skin and the very beneficial results of this reaction, which might be a massive confound in some of the vit D studies.