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Vitamin D, part 3 – The Evidence

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Re: Vitamin D, part 3 – The Evidence

#181

Post by DoreenMichele »

A few thoughts:

Expecting vitamin D supplementation to be some cure-all is silly on the face of it. It's like saying "Your building has a brick deficiency" after some disaster does egregious harm to it and then ordering a bunch of bricks or starting a charity to give away free bricks to the entire community after a hurricane levels things.

Yes, bricks may well be a critical ingredient necessary to rebuild, but getting a giant pile of bricks dropped at your front door is the start of the rebuilding process, not the end of it. And then you will find that you may not able to do anything with your pile of bricks because there's no mortar to hold them together or there are no skilled brick layers available.

The body is a very complex machine. It really shouldn't surprise anyone that a simple solution -- like "needs more vitamin D" -- isn't going to miraculously get it working better across all categories of things that can go wrong, either due to a deficiency or in a way that will cause a deficiency.

Re: Vitamin D, part 3 – The Evidence

#182

Post by Jeriko »

harterrt wrote: post #162
devaboone wrote: post #110

Earlier quoted context omitted.

Here is what the article states: "Therefore, a multivariate logistic regression analysis was performed to adjust the model by possible confounding variables such as hypertension and type 2 diabetes mellitus for the probability of the admission to the Intensive Care Unit in patients with Calcifediol treatment vs Without Calcifediol treatment (odds ratio: 0.03 (95%CI: 0.003-0.25) (Table 3). The dependent variable consi…

Unless I'm reading your comment wrong, this p-value (0.03) is actually significant for a 95% confidence test.

0.03 is the odds ratio (a measure of effect size, an odds ratio of 1 would mean the treatment and control arms had the same rate of ICU admittance). The p value is 0.08 from here "CI:-0.30 - 0.03 p:0.08." which captures the likelihood the treatment had an effect.

That said, just looking at p values and applying a cutoff at 0.05 is pretty bad practice that is getting a lot of heat thanks to the replication crisis (does it make sense to behave as though p=0.08 is not true and something at p=0.049 is true? almost certainly not). If you get a value in this range and a huge effect size then it's a really good idea to repeat the experiment with way more data. It's also a common stats error to act as though p>0.05 is the same as knowing something DOES NOT work, all you can say is this specific study wasn't able to show that it does work with 95% confidence.

Re: Vitamin D, part 3 – The Evidence

#183

Post by geoka9 »

gwd wrote: post #37
m12k wrote: post #2

So Vitamin D deficiency is linked to cancer, heart disease, respiratory infection, stroke, diabetes, and death. But taking it as a supplement helps with none of the above. What is a reasonable hypothesis then? That having an active lifestyle that brings you outside in the sun both causes your Vitamin D to go up, and is correlated with better physical health in general?

From TFA: > How can we reconcile promising early observational studies linking Vitamin D to most major causes of death with our current results? One thing that seems increasingly clear is that in most cases low Vitamin D (truly low Vitamin D) is a marker of poor health rather than a cause. Vitamin D is made in the skin after exposure to sunlight. A chronically ill, frail individual may leave the house less often, lea…

TFA == "The Fucking Article"

Re: Vitamin D, part 3 – The Evidence

#184

Post by DoreenMichele »

geoka9 wrote: post #183
gwd wrote: post #37

Earlier quoted context omitted.

From TFA: > How can we reconcile promising early observational studies linking Vitamin D to most major causes of death with our current results? One thing that seems increasingly clear is that in most cases low Vitamin D (truly low Vitamin D) is a marker of poor health rather than a cause. Vitamin D is made in the skin after exposure to sunlight. A chronically ill, frail individual may leave the house less often, lea…

TFA == "The Fucking Article"

Although that's what I originally learned it to mean -- from a horribly toxic online space -- some people use TFA to mean "The Featured Article" aka "the article under discussion."

Re: Vitamin D, part 3 – The Evidence

#185

Post by dorenarode »

I read Dr. Boone's article and looked over each intervention in the study's she listed. I noticed that many researchers were dosing once a month (one was only once a year!) at levels I would not consider therapeutic. Yes, at non-therapeutic levels, I would expect vitamin D to not show much difference from Placebo. I am not a vitamin D expert, but am wondering why she selected to discuss research that didn't even match current vitamin D recommnedations. Her favorite research was VITAL which I was thrilled to learn was daily for 5 years. Unfortunately, it was at a level (2000IUs) that could leave many people at subnormal levels of vitamin D. 1000 IU will bring up blood levels 5 ng/mL. 30 ng/Ml is considered okay. Many people believe that levels between 60-100 ng/mL is better. I have a genetic defect that keeps me below 30ng/ml regardless of sun exposure. I supplement at 15000 IU per day. Which brings my levels up around 70-90ng/mL

Re: Vitamin D, part 3 – The Evidence

#186

Post by gwd »

geoka9 wrote: post #183
gwd wrote: post #37

Earlier quoted context omitted.

From TFA: > How can we reconcile promising early observational studies linking Vitamin D to most major causes of death with our current results? One thing that seems increasingly clear is that in most cases low Vitamin D (truly low Vitamin D) is a marker of poor health rather than a cause. Vitamin D is made in the skin after exposure to sunlight. A chronically ill, frail individual may leave the house less often, lea…

TFA == "The Fucking Article"

And nice means "mean or small-minded", and silly means "saintly", and terrible means "inspiring terror". Or at least they used to -- but usage evolves over time past etymological roots.

"TFA" is indeed a back-formation from "RTFA", which is the online-forum equivalent of the aggressive and obnoxious acronym "RTFM". But it contains no verb; and in online discussions there's a sort of a hole in our language for an efficient way to say for "the article currently under discussion". So it quickly lost the aggressive and obnoxious connotations that RFTA has.

As such, I think "The Fine Article" is an expansion more fitting with its evolved usage.

Re: Vitamin D, part 3 – The Evidence

#187

Post by pmayrgundter »

harterrt wrote: post #162
devaboone wrote: post #110

Earlier quoted context omitted.

Here is what the article states: "Therefore, a multivariate logistic regression analysis was performed to adjust the model by possible confounding variables such as hypertension and type 2 diabetes mellitus for the probability of the admission to the Intensive Care Unit in patients with Calcifediol treatment vs Without Calcifediol treatment (odds ratio: 0.03 (95%CI: 0.003-0.25) (Table 3). The dependent variable consi…

Unless I'm reading your comment wrong, this p-value (0.03) is actually significant for a 95% confidence test.

That's part of the confidence interval. The adjusted p-value is 0.08. However, the cut-off of 0.05 is just a convention. https://en.wikipedia.org/wiki/Misuse_of_p-values. I'd think of this as a grey scale, where 0.08 is roughly in the significance range.

The null hypothesis is that it's highly unlikely VitD has an effect, and we should expect to see that substantiated often in tests. How often? 95% of the time. 5% of the time we can expect to see spurious results from our simplistic model of random processes. Upshot, it's a small change to move those numbers to 92% vs. 8%. In this context, it's fine to say "this was a small pilot that directionally shows we should do a much bigger test", which is what they're now doing.

Re: Vitamin D, part 3 – The Evidence

#188

Post by leftyted »

tchaffee wrote: post #144
api wrote: post #25

The most obvious evidence to me has always been that Europeans are not black. A change like the loss of melanin requires selective pressure, which in this case was likely furnished by less vitamin D as we migrated away from the equator. The pressure must have been significant since being white carries a big downside: higher vulnerability to sunburn and skin cancer. When I lived in Cali I always envied my darker skinn…

> A change like the loss of melanin requires selective pressure It does? What about genetic drift, random mutations, and artificial selection, where humans select based on qualities not necessarily conducive to survival? There is also some evidence that this change in skin color was only widespread as recently as 8,000 years ago [1]. > which in this case was likely furnished by less vitamin D How likely? > The pressu…

> It does? What about genetic drift, random mutations, and artificial selection, where humans select based on qualities not necessarily conducive to survival?

It seems unlikely to be due to these factors since there's a gradient from black to white as you move away from the equator.

Re: Vitamin D, part 3 – The Evidence

#189

Post by mancerayder »

citruscomputing wrote: post #136
tarsinge wrote: post #129

Earlier quoted context omitted.

I’m healthy, fit and relatively active (3-4 hours exercise / week, 30-1h walk everyday), and I just tested relatively low in Vitamin D (before winter even started). What should I do?

Talk to your doctor.

You must have some great doctors to ask questions like these to. In my experience there's nothing cutting edge about any answers I ever got from a doctor, and more often than not it's a predictable, nothing-to-see-here attitude. And I learned long ago to be cautious when I say something like, "I was reading about a study that suggested..." as you risk getting pinned with the loons at worst, and mostly ignored at best.

Re: Vitamin D, part 3 – The Evidence

#190

Post by tchaffee »

0-_-0 wrote: post #160
tchaffee wrote: post #153

Earlier quoted context omitted.

If you look at the full quote, the purpose is not to confirm your theory but to inject healthy doubt in your theory: "A sun lower in the sky and shorter day lengths would have favored skin that more easily synthesized vitamin D. But researchers are now learning that other factors must have been at play." > The article also points out a correlation between latitude and light skin Well yes, exactly. Correlation. I aske…

I read the article but failed to see what doubt it sheds on the idea that light skin evolved to increase vitamin D production. Could you help me find it please? You asked for evidence of causation, which I provided. Correlation of latitude with skin colour is evidence of causation. Light skin colour providing vitamin D while increasing skin cancer risk is evidence of causation. No other known advantage of light skin…

> Correlation of latitude with skin colour is evidence of causation.

Correlation is not causation. I'm sorry but I don't think you have any evidence at all that lighter skin was caused by a need for more vitamin D. It's just an educated guess on your part. Lighter skin could have just as easily been an adaptation related to less visibility to predators and prey in snow. Like the article I cited said "researchers are now learning that other factors must have been at play."

And with the article that started this thread we now have quite a few studies telling us that vitamin D supplementation doesn't do anything helpful. So why would humans undergo an adaptation that provides no benefit? Perhaps exposure to the sun provides health benefits? Or is it that healthy people get outside more and therefor have higher vitamin D levels? I'm happy saying "I don't know" and asking more questions. I encourage you to do the same instead of claiming causation when all you have is correlation.

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