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Comment by xnickb | Hacker News Reader

> severe VDD was defined as serum 25(OH)D levels of <25 nmol/L, moderate deficiency as 25–50 nmol/L, insufficiency as 50–75 nmol/L, and sufficiency as >75 nmol/L.

These numbers seem high to me. The 75 nmol/L (30ng/L) is not really a reliable value. It was published in a research that raises many questions due to conflict of interests.

Hence the

> ~40% of people don't get enough vitamin D

becomes:

> ~40% of people in the USA don't get enough vitamin D according to Dr. Holick

Where I live the norm is 20 ng/L and if we apply that, then the shocking 40% becomes more reasonable 10-15%

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Insufficient in Ireland is also set at 30--50 nmol/L (12--20 ng/mL).

Sunlight UVB radiation needed to make vitamin D is only available in Ireland during the months of April through October. This is due to our geographic location 52o - 55o North and means that Ireland experiences a ‘vitamin D winter’ that stretches from the end of October to late March.

Currently, 94 % of children, 94 % of teenagers and 90 % of adults on the island of Ireland have inadequate vitamin D intakes. Therefore, almost everybody in Ireland needs a supplement of vitamin D and 15 µg (600 IU) is recommended on a daily basis.

N.B. In the early 2000s, over 20 cases of rickets (a weakening of the bones caused by severe vitamin D deficiency) in infants and toddlers were reported in Ireland.

> Where I live the norm is 20 ng/L

How did they come to this?

Seems like a reasonable measure would be to look at a native person, from ones lineage, having a relatively average pre-industrial day.

If lineage doesn't matter, and all humans are the same, you could probably just go sample some tribe members that still lives mostly outdoors, outside of developed society.

And, regardless, I'll listen to my doctor.

you're asking the question the wrong way around. How did Dr. Holick come up with 30ng/L and what were his incentives?

Clearly he made a lot of money publishing that research. And people who paid him also made billions. But let's focus on the rest of the world that didn't increase the norm that works by 50%

I don't want to go into this debate. The cited benefits of Vitamin D have to do with Calcium and bones. This is just absurd to me. Do people in Europe have brittle bones? Those 40% with alleged Vitamin D deficiency have issues with Calcium and get bone fractures every other day?

There is no substance to discuss here, sorry.

Vitamin D deficiency manifests itself as rickets (weakening of the bones) in children and osteomalacia (softening of the bones) in adults. Less severe vitamin D deficiency contributes to osteoporosis (bones are weaker and more likely to break). All of these are well documented outcomes in Western Europe.

More to the point, since Covid Researchers have posited that Vitamin D plays a critical role in preventing respiratory infections, reducing antibiotic use, and boosting the immune system response to infections. Vitamin D is important in regulation and suppression of the inflammatory cytokine response, which plays a role in the severe consequences of COVID-19 and ‘acute respiratory distress syndrome’ associated with ventilation and mortality in COVID-19. Vitamin D also helps the respiratory tract produce antimicrobial peptides that can lower viral replication rates.

RAPID EVIDENCE SUMMARY: VITAMIN D IN COVID-19 https://assets.gov.ie/static/documents/rapid-evidence-summar...

The causal role of vitamin d deficiency in worse Covid-19 outcomes: implications for policy and practice development https://repository.rcsi.com/articles/journal_contribution/Th...

Coronavirus disease 2019 and vitamin D https://pmc.ncbi.nlm.nih.gov/articles/PMC10277257/

Vitamin-D and COVID-19: do deficient risk a poorer outcome? https://www.thelancet.com/journals/landia/article/PIIS2213-8...

All the articles you linked consider 20ng/mL is normal level 30ng/mL is sometimes recommended.

Am I talking to AI?

Am I talking to a particularly obtuse LLM?

Roughly 20% of the UK population (1 in 5 people) is clinically deficient (<20 ng/mL). Similar in Ireland.

If we extrapolate slightly from 'clinically deficient' to 'subnormal' then 94 % of children, 94 % of teenagers and 90 % of adults on the island of Ireland have inadequate vitamin D intakes. This is because the Sunlight UVB radiation needed to make vitamin D is only available in Ireland during the months of April through October.

For us and the other latitudes which experience a ‘vitamin D winter’ that stretches from the end of October to late March, almost everybody in Ireland needs a supplement of vitamin D and 15 µg (600 IU) is recommended on a daily basis.

I have no idea what that has to do with my point. Thanks for sharing though. It is curious data.

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> Do people in Europe have brittle bones?

And, now you've discovered why Europeans have light skin [1]! And, why supplementation is suggested for those with dark skin [2] living in regions with light skinned natives!

[1] https://www.science.org/content/article/how-europeans-evolve...

> But the likely explanation for the pigmentation genes is to maximize vitamin D synthesis

[2] https://www.cooperinstitute.org/blog/african-americans-at-gr...

> And, now you've discovered why Europeans have light skin [1]! And, why supplementation is suggested for those with dark skin [2] living in regions with light skinned natives!

What does the color of skin have to do with the normal amount of a vitamin in blood?

Skin tone merely regulates how much you end up producing. Just because your skin is bright doesn't mean you need less of a vitamin.

I'm sure there is some variance in this, but I doubt it's swinging between 20 and 30 ng/mL

Because vitamin d is produced by sun. Light skin means less sun is required. I suggest a cursory look into vitamin d production [1], to more align your perspective to accepted science.

[1] also covers evolution of skin tone https://en.wikipedia.org/wiki/Vitamin_D

Are you kidding? The discussion is explicitly about the normal levels. How much you produce is irrelevant. The _level_. As in how much of it is floating in your blood.

Some levels are normal, some are low. "Skin color" affects production as you pointed out, but that has literally nothing to do with what we are discussing.

It's not some "your bones fall apart if you're low". It's just like literally every other nutrition related thing. You can have too little or too much. Bad things increase the more you go towards either direction.

For knowing how much blood level is "good", if you go back [1], that's why I suggested a good starting point would be looking at any native with an average pre civilization type days worth of outdoor activity and attire. For example, native African in their sunny climate, native European in their cloudy climate, etc. You probably also have to look at their pre-civilization diets, if they were too different from the average today (like traditional Inuit diet).

And, as I said, if there's no difference to be expected in baseline "healthy" vitamin D levels across genetic populations (a native African or native European), you could just go same some people in Africa or Papa New Guinea, right now, where you can find some populations living (at least very close to) pre-civilization lives, and measure theirs for some reasonable ground truth.

Cheers!

[1] https://news.ycombinator.com/item?id=49838612

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