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.

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.

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.

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

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.

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.

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).

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.

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

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.