Vitamin D3 During Pregnancy and Cognitive Performance at 10 Years

> We found that high-dose supplementation was positively associated with 3 of 11 functions assessed: verbal memory, visual memory, and flexibility or set shift. However, the association with flexibility or set shift was not significant after correction for multiple testing.

They tested 11 different measures. Only 3 of those tests showed significance, but after they corrected for multiple testing the significance of 2 of those disappeared. Only 1 test remained below the significance threshold.

This is on a set size of about 500 children who completed the study, randomized to the two groups.

The only measure that remained statistically significant was visual memory. If you look at Figure 2 it's not even clear that there was a trend toward improvement because everything is so scattered, including a couple measures that were trending worse with higher Vitamin D levels.

This study isn't very convincing. It's a classic p-hacking trick to include many different smaller tests so if one of them pops up as an outlier you can claim that something was significant.

Vitamin D excess can lower blood levels of vitamin K2, reducing bone development. Not sure if the levels would be high enough for this (difficult to find safe numbers for in utero), but the side effects, joint pains, stiffness, could have motivated the kids to stay indoors and focus on more intellectual pursuits, leading to better cognitive performance.

I point this out because there are so many known factors both positive and negative that contribute to increased 'cognitive performance' it is impossible to account for all of them, even within a randomized trail such as this. People are weak to assumptions when it comes to correlation.

I have thoughts on this

1. Yes, vitamin D actually controls a lot of bodily functions it’s very easily set aside as not a “main” factor when in reality it actually controls a lot

2. This study was done on women in Denmark only which isn’t a great study subject considering Denmark doesn’t get a lot of sun to begin with so most of these women would already start at very low levels

3. This doesn’t directly correlate to women of color because WOC need higher dosage of vitamin D than white women do. The general range of “good” level of vitamin D that doctors tend to use is related to studies results gotten from white people when in reality brown and black people need way more for their range to be at a normal place.

> the association with flexibility or set shift did not remain significant after false discovery rate correction

this is right there in the abstract, isn't that the entire game?

I'm perhaps missing something but if there were a significant connection, wouldn't this mean those in sunnier climates would have better verbal and visual memory?

If there were a connection then I would wager that there are more significant factors, since I have seen or heard of no evidence to assume those in sunnier climates have better verbal and visual memory.

The results of this study seem to show no significant correlation, anyhow.

I'd read this less as "high-dose vitamin D makes kids smarter" and more as "prenatal vitamin D might matter for some neurodevelopmental outcomes, and it’s worth testing more directly"

I'm not sure if there are any research showcasing the effects humanity has had in general due to low sun exposure. From all the benefits of Vitamin D and the recent human behavorial shift leading to low sun exposure (car travel, air conditioning, sunscreens even), there are bound to be new biological or psychological changes humanity is experiencing for the first time.

Tangentially, with ai tools available, post hoc secondary analysis of studies (like this) has to be insanely easier to run through. Are there are companies/individuals focused on this specifically? Obviously most labs are doing some of this but I’m curious if there are broader analysis being done

Can you say p-hacking? It was designed and powered to test whether prenatal vitamin D reduces childhood asthma/wheeze, and found no effect on that primary outcome. The rest is just shuffling numbers and statistical methods around until something with p > .05 pops out.

They flags their own post hoc status, reports modest effect sizes, and applies some multiple-comparison correction. That makes the rhetorical sleight of hand harder to spot, because it's buried inside otherwise careful looking work.

The statistics are shit. They applied Benjamini-Hochberg FDR correction within cognitive domains, not across the family of 11 functions. That choice is what produced the headline "memory survived correction."

Watch what happens with the actual numbers. The two "winning" functions, verbal memory (p = .02) and visual memory (p = .01), both sit inside the memory domain — which contains exactly those two functions. BH within a 2-member family barely adjusts anything: the most lenient threshold is just 0.05, and both p-values are already under it, so the q-values come back at .02 and .02. The correction was toothless by construction, because the two hits happened to fall in the same tiny domain. A reviewer should have made them show the whole-family result side by side. The fact that they didn't is the tell. And there is much more that could be criticized in the same manner across the whole thing.

And then the observational data fail to corroborate the supplementation finding. The authors explain the mismatch via trimester timing of exposure, which is plausible, but the equally plausible reading is that the RCT hits are fragile, or that, more probably, it's not a real effect.

And even if there was an effect, it's so small and weak and NOT proven by even this data, that the recommendation for supplementation is not warranted at all. At best, this single study with their focus on recreating this effect is the only defensible conclusion. And yet they recommend supplementation.This is pure bias and D-vitamin cult babble once again.

The conclusion, based on the actual data, is: in a vitamin-D-sufficient cohort, high-dose prenatal D3 was not associated with offspring cognition on any whole-battery-corrected measure.

I hate this so much because it's stupidity like this that shows that science is not worth paying attention to, because the scientists basically lie through their teeth, at least from my perspective, where truth is something that is verifiable and relates to something real.

Based on how many tests they did and the confidence intervals they got it's associated with fuck all. Doing lots of tests and then pointing to the few where the lower bound of the effect size was marginally above 0 proves very little.

At any rate their main marker for intelligence showed an impressive p=90%, so whatever cognitive effects were present they've not made them any smarter (at 10).

I don't know, the study seems pretty mild in findings and the research doesn't mention anything about the socioeconomic environment in which each of the children grew in.

Maybe it's the high dose vitamin, maybe it's because one cohort was skewed one way on the socioeconomic spectrum, maybe it's something else entirely. More evidence would be needed imo to confirm Vitamin D3 has a direct contributor to cognitive performance as the research portrayed.

high dosage vitamin D in kept me sane (i.e energetic & in the right mood) in the UK where it's usually gloom & drowsy.

Meanwhile, the endocrine society is still murdering millions by asking people to not supplement vitamin D3 and to explicitly not test for it either. The times must be tough for endocrinologists with people supplementing high-dose vitamin D3 and testing routinely to ensure an optimal level, tough enough to want to keep people very sick.

the Vitamin D cult is a bit insane

it is -exactly- like Linus Pauling and Vitamin C cult in the previous century

Vitamin D is very important

Too Much is as bad as Too Little

The "RDA" is too low at 600IU and should have been changed to 2000IU decades ago

It can help prevent certain diseases and illnesses

It CANNOT cure any known disease or illness once afllicted

I guess I don't understand why this study is suddenly getting attention when these kinds of trials have been going on for years. This one doesn't seem to have a particularly strong methodology or particularly unusual findings. It's just another page in a very, very long record of evidence about vitamin D, and by no means settles any major controversy.

This is exactly what I've been thinking about lately. The modern knowledge-worker lifestyle is practically an experiment in extreme sun deprivation. We optimize our indoor spaces with perfect AC, ergonomic setups, and even custom ambient noise apps just to stay locked in a room for 10 hours a day doing deep work.

It makes you wonder how much of what we accept as "normal" afternoon brain fog or tech burnout is actually just our biology reacting to this massive behavioral shift and lack of natural light.

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