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Traubenfuchs

You are right and it is no secret:

- 40% of US Americans are B12 deficient https://www.livekindly.co/b12-deficiency-genetic-makeup/#:~:....

- 42% are Vitamin D deficient: https://www.cantonmercy.org/healthchat/42-percent-of-america....

- up to 50% are Magnesium deficient: https://www.sciencedaily.com/releases/2018/02/180226122548.h...

- 10 - 20% of women are iron deficient: https://www.aafp.org/afp/2007/0301/p671.html#:~:text=The%20p....

My unscientific conclusion is that the vast majority of people world-wide probably suffer from at least one and probably more significant nutrient deficiency. With that we are wasting our "performance potential" and, less capitalistic, our "well-being potential". The lack of any of just those nutrients I looked up can cause anything from debilitating brain fog, over physical and mental deterioration to numerous physical ailments...

Yet for most of them, taking them in excess causes the exact same problem. If I was filthy rich I would get nutrient levels measured once a week. (-;

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I wouldn't be surprised if quarantine is leading to an historic spike in D deficiency.

I suspect it's exactly the opposite.

During quarantine, you have far fewer people spending most of their waking hours in huge concrete coffins.

How many people even get to see the sun during a typical workday, much less spend time in direct sunlight?

In big cities like NYC people get sunlight during their commute, but get no sunlight when cooped up in a small apartment. Vitamin D deficiency has been long proven to inhibit proper functioning of the immune system, but this isn't widely known which is a huge failure of the press and the authorities.

it's also specifically very good for respiratory diseases apparently.

    In big cities like NYC people get sunlight during 
    their commute

Perhaps you have only seen NYC in movies. You can spend a lot of time commuting in NYC without any direct sunlight hitting your skin whatsoever.

Not sure when you think they're soaking up all this sunlight. Sitting in a train car? ...that's underground? Or inside a bus? Or is it when they are walking between tall buildings?

New Yorkers are not exactly known for their tans, even in summertime.

    but get no sunlight when cooped up in a small apartment

You were not forced to stay in your apartment, even in NYC. You were always allowed to leave. Of course, most businesses are/were closed, but you are/were certainly allowed to walk around. Many people also have access to their apartment rooftops.

Perhaps more relevantly, of course, most Americans do not live in places like NYC where they have difficulty accessing sources of sunlight. I live in a suburb of a different American city and we are getting much more sunlight during quarantine. It's much easier to take walks and sunlight breaks during the daytime.

That's definitely my personal case.

I moved from Brazil to the UK 6 years ago and have since developed a semi-transparent quality on my skin.

1 month into the quarantine and I have a great tan and look like a healthy human. The healthy part is probably in part due to better sleep and a lot less exposure to pollution but sunlight definitely helps.

I haven't been this tan in years! It's been really easy to go outside for a walk, I hope to keep it up in the coming years...

We have been seeing a lot of that on the hiking trails around here. They're swamped, mask compliance is near zero and they're litterbugs. We are also getting undesirable elements out there--vandalism and things like snatching phones.

Oh man, I've never seen so many people out walking in my neighborhood during the day as at the height of the "lockdown". I bet foot traffic was up 5x normal per week, or more. 10:1 it's exactly the opposite and vitamin D levels have improved.

Or maybe, 10x that many people walk to lunch at work and foot traffic is actually down by 50%, but you're just seeing it happen in a different place.

I think that varies greatly depending on the area. Some places you weren't supposed to leave your house, others the parks were still open for walking. Also, some places are more pedestrian-friendly than others.

I've always wondered about this deficiency thing. How is it defined, and does it make any sense to claim that such a large part of the population is deficient? Shouldn't that be considered "normal" (excluding the truly pathological cases), as opposed to "above-average"?

Average is not necessarily within the healthy range. See also: weight, diet, etc.

At least for Vit D and B12, the healthy levels were determined by establishing levels in "healthy" cohorts. Deficiency diseases for both of these vitamins are relatively rare, so it is easier to establish a wider "safe" range, rather than "deficiency" ranges.

There's been a great deal of debate on safe Vit D levels, and the consensus (such as it is) is that a serum level of 30 ng/mL is likely optimal. Yet there are many studies that show healthy individuals with serum levels < 10 ng/mL, and they do not seem to suffer the bone abnormalities expected.

There's a similar situation with Vit B12. Reference ranges were established from healthy individuals based on dietary intake, and there is no upper limit. It's also unclear what the bottom of the healthy range is either. A relatively recent investigation by the health authorities in India found that the dietary intake of B12 of the average Indian was less than a tenth of the US average, with no obvious ill effects. B12 deficiency diseases are practically unheard of in India, yet when tested against American references, a large portion of the population is "deficient". The Indian authorities eventually set the recommended intake of B12 to the WHO standard, which is a lot lower than the American or European levels.

> Yet there are many studies that show healthy individuals with serum levels < 10 ng/mL, and they do not seem to suffer the bone abnormalities expected.

The problem is that any apparently healthy individual may still develop a chronic disease decades down the line.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440113/

> There's been a great deal of debate on safe Vit D levels, and the consensus (such as it is) is that a serum level of 30 ng/mL is likely optimal.

If you look at dark-skinned hunter-gatherer tribes which are living in a way closer to our common ancestors, the "natural" Vitamin-D levels in their relatively sunny environment is more like 40 to 50. The body seems regulate Vitamin-D production up that level, so that's probably closer to optimal than 30.

>The problem is that any apparently healthy individual may still develop a chronic disease decades down the line.

Sure. My impression is that sub 10 ng/mL levels warrant supplementation. However, I have also seen studies that included wrist X-rays of subjects to determine bone loss, and most subjects were sub-20 ng/mL with acceptable bone densities. This was a study in Indians, and another study in rural healthy Indians showed most were in the sub-20 ng/mL range, coupled with low dietary calcium intake, and no ill effect. While it's true that they may develop problems decades down the line, a longitudinal study like this demonstrates that Vit D related deficiency diseases are actually quite rare, and at levels far lower than would be expected from the serum levels alone. There's clearly more going on.

https://pubmed.ncbi.nlm.nih.gov/17413106/

On the Hunter-Gatherer levels, I'm guessing you're referring to the Masaai and Hadzabe study. However, is this the optimal vitamin D level?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6180659/

This study from healthy black blood donors in Nairobi found much lower levels (95% CI 12.73–22.07), and these people had significant sun exposure as well. Rather importantly, they note that while parathyroid hormone levels are inversely proportional to Vit D serum levels, they start to go up with high levels of Vit D. Individuals with 50 ng/mL vit D had PTH levels similar to people with a Vit D serum level of 15 ng/mL. PTH causes calcium levels in the blood to go up, drawing them out from skeletal reserves. The health implications of high Vitamin D supplementation are linked to the inappropriate deposition of calcium. Keeping PTH levels low is likely beneficial. The Nairobi study found PTH levels were lowest in people with vit D levels around 30 ng/mL.

> Rather importantly, they note that while parathyroid hormone levels are inversely proportional to Vit D serum levels, they start to go up with high levels of Vit D.

...in that particular polynomial fit.

> Keeping PTH levels low is likely beneficial. The Nairobi study found PTH levels were lowest in people with vit D levels around 30 ng/mL.

The minimum of the polynomial fit is around 35. If you look at the scatter plot, there are only six samples near 50 ng/ml and they're all over the place. You can not draw your conclusion from that. There's no significant deviation between 40-50 ng/ml.

My question is, why would the body stop producing Vitamin D around 40-50 ng/ml if 30 was optimal? Why not stop earlier?

> Keeping PTH levels low is likely beneficial.

Not sure where you get that.

To me, I am less convinced that the elevated levels in the Masaai represent an ideal. Do all hunter gatherers have such high levels? Unclear. Perhaps the Masaai have such high levels as a quirk of their genetics, and their particular lifestyle. Does that necessarily translate into an ideal level for all humans? Possible, but there just isn't enough data. On the other hand, there are many studies across populations that find levels plateauing around 20 ng/mL for healthy rural cohorts, with no negative outcomes.

Why does the body stop producing Vitamin D around 50 ng/mL, if it wasn't the ideal? Vitamin D toxicity only kicks in at extremely high levels, several orders of magnitude higher than are naturally produced. So why would nature even bother to set an upper limit at 50 ng/mL? It doesn't, though. Vitamin D3 is produced by a reversible photosynthetic reaction, and is constantly being degraded as well under sun exposure. 50 ng/mL possibly represents the upper limit at the speed with which D3 can be transported away from the dermis, and the limits of natural exposure levels. My feeling is that rather than an evolutionarily fine tuned level, this is a "good enough" local maxima as an upper limit for D3 production under natural conditions. If the Masaai were somehow exposed to 20 hours of full sun, their levels might very well be much higher.

As a thought experiment, if humans were exposed to 20 hours of sunlight, would we evolve fewer keratinocytes to keep vitamin D levels at the 50 ng/mL level? Or perhaps evolve less efficient enzymes to produce lower levels of the precursor? My impression is that there isn't a strong enough disadvantage to higher levels of Vitamin D for evolution to push in that direction. So rather than an ideal level, 50 ng/mL might simply represent the upper limit of what humans can produce under natural conditions.

Are there really no better studies than just those that categorize "healthy" cohorts & establish standards from that? That would presume a linear causal relation between "health" and vitamin levels in the body which would flip the order of operations - you want to establish a linear causal relation before you start recommending levels.

Well, establishing a linear causal relation isn't always possible, at least not ethically. The recommendations have to balance average dietary intake, tolerable upper limits, and what would constitute an adequate intake that is both necessary and sufficient. For Vitamin C, for example, toxicity is probably in the 2-3 grams range, while just 10 mg/day is sufficient to overcome symptoms of deficiency. So what should the recommended daily allowance be? You don’t want to set it at the minimum level, to allow for individual variances and greater needs among particular groups. You also don’t want to set it artificially too high. Different agencies and countries draw that line differently. Japan sets it at 100 mg/day, while India at 40 mg/day. The Indian agencies have to be cognizant of the fact that given average Indian diets, setting the "healthy" level at 100 mg/day would artificially pathologize most Indians who do not suffer from Vit C deficiency symptoms.

The situation is more complicated with recommendations around vitamin D. The most obvious and extreme abnormality associated with low D is bone demineralization. This is largely alleviated by levels above 12 ng/mL. Yet when you look a cohort of healthy young Caucasian coast guards, their vitamin D levels are 30 ng/mL. So what do you set as the recommendation: the level required to prevent symptoms, or the levels seen in (some) healthy people, but with no obvious health advantages? Most groups have tended to split the difference: set the minimum at 20 ng/mL, and the “optimal” at 30 ng/mL. Is there a health benefit with supplementing if the level is below 10 ng/mL? Quite likely. Is there a health benefit supplementing if your level is at 20 ng/mL? Probably not.

The picture is even further complicated if you consider that the healthy cohort of young white coast guards in Hawaii is not representative of the population at large. Multiple studies have looked at healthy black and brown cohorts from tropical environments, and find most average around 20 ng/mL.

Right. I think your arguing my point. The correct way is to understand what the different levels are for each cohort & provide guidance based around your risk factors. We don't know though what that looks like so everyone is stumbling around in the dark. Picking 1 number to recommend nationally/globally is just silly as you point out. Too many factors.

To be fair, even within the national recommendations, there may be different levels suggested for different groups. There are usually separate numbers suggested for infants, children, teenagers, adult men & women, the elderly, and pregnant/nursing women. The numbers that get tossed around most often are for adult men, but the separate recommendations do exist. The goal of the recommendations is to cover the needs of more than 97% of the group. Your doctor should be able to tweak those recommendations for your individual needs, as required.

there are recommended serum levels for B12: >200pg/mL for Europeans

Excess Vitamin D doesn't do anything (within reason), but the immune system doesn't work properly when you're vitamin D deficient, and this is something we can measure. Humans haven't evolved for an entirely indoor lifestyle, and we need daily direct sunlight in order to function properly.

I do 5000 IU per day. NIH recommends 600 IU for most people [1]. The Institute of Medicine says 4k IU as the safe upper level of daily intake.

Vitamin D does wonders for my skin. Not once did a dermatologist suggest I could be deficient. I figured it out on my own.

Here is a good resource for research on vitamins and minerals and their applications:

https://www.informationisbeautiful.net/visualizations/snake-...

[1] https://ods.od.nih.gov/factsheets/VitaminD-Consumer/

[2] https://www.healthline.com/nutrition/how-much-vitamin-d-is-t...

Similarly with drinking 3 litres of water a day, or you're dehydrated. How did our ancestors get 3 litres of water a day? Seems like the first person ever who wasn't dehydrated was born around 1985.

I don't know how true it is and I don't remember the source, but I recall hearing somewhere that you also get a lot of hydration through food sources. So it's not necessarily that you need to drink a lot of water to stay hydrated.

I guess that might also be why people say to drink more water when you have diarrhea. The absorption of water that usually happens during digestion is not occurring.

The research was seriously misreported--you don't actually need to drink anything like that much, the number is for total dietary intake in any form. With enough juicy food there's no need to actually drink anything. I'm reminded of one day my wife saying she was thirsty, please cut a slice of watermelon. At first I thought it was an English mistake (it's not her native language) but that's really what she meant.

Presumably it's relatively easy for a lab to run a panel of tests on me and say "you're deficient in X, Y, Z; try eating more A B C; spend 30mins extra a week outside; drink less alcohol".

How easy is it too get such tests (in UK), I'm surprised we don't seem to have anything like this as part of our health system. I've had blood pressure and height/weight taken a couple of times (I'm middle aged). But that's about all wrt biological metrics, seems lackadaisical?

Just measuring those 4 costs 83€ in a laboratory in Vienna. And there are more measurements one should probably take! And you need to test them more than once to see if supplementation works and you are not getting too much.

That's not cheap...

I had a load of blood tests done in the uk and the health insurance company were charged over £1000. I couldn’t believe it!

Define "a lot"

I remember doing some tests once that had a cost breakdown and they would vary a lot in price (meaning some would be let's say, single digits, some others would be in the triple digits area - think USD/EUR price ranges)

We're talking an expense of somewhere around 1k total over a period of a few months. While not within everyone's reach (and if a single check is performed say yearly after initial alteration of your diet also an ongoing expense), it's far from an insurmountable cost. Especially considering this directly impacts your day-to-day well-being.

If shouldered by the individual, an extra $1k over a few months, plus however much it costs to keep re-testing, and the cost of supplements or better food to correct the deficiency, is a staggeringly insurmountable cost for the people who need it most—the poor.

As you say, this directly impacts day-to-day wellbeing. It's exactly the kind of thing that should, if it's even moderately effective, be provided free of charge for every human being.

I agree with you, but I must also admit it's not much of a concern if you live in a country with solid health insurance.

It should be part of the health system. For now in the UK we have lab services like this one: https://thriva.co/ (not affiliated). You send your blood by post and they analyse it.

For some nutrients it’s easy to test for, for others the tests are controversial with regards to accuracy.

I can't speak for all nutrients, but it's nearly impossible to detect magnesium deficiency in blood tests. Presumably, other nutrients might be difficult to check as well. Which makes the tests misleading or downright wrong.

The medical school at the university nearest me offers a range of such tests on a walk-in basis for prices ranging from around $15-40 USD each. Obviously, YMMV, but inquire with any medical schools near you that have research hospitals or training clinics.

There is still the question of why so many people are deficient in B12, D, iron, and magnesium. Is it because they don't eat enough of those specific vitamins/minerals or is it because their kidneys/livers/other organs have been damaged by a modern diet or by stress or through environmental pollutants. I'm willing to bet that in developed nations, it is less deficiency of vitamins or minerals in diet and more a defect of the body.

I just followed the link you posted about 40% being B12 deficient but could not find 40% mentioned anywhere other than the headline.

There is a link in the second paragraph. https://www.emaxhealth.com/13955/vitamin-d-deficiency-and-ge...

I am not writing a peer reviewed article. Just wanted to throw out some numbers to engage with the thought of widespread deficiencies. If you want more reliable information there is lots of material available online.

> There is a link in the second paragraph. https://www.emaxhealth.com/13955/vitamin-d-deficiency-and-ge....

Those links are to studies which do not support the 40% claim. They are basic science research about vitamin interactions in the human body. Please consider that if you can't find studies showing "widespread deficiencies," then perhaps they don't exist.

The only one of your links which involves a survey which justifies the claim is the one on iron deficiencies.

Genuine question: so how do we fix nutrient deficiency for vast majority of people world-wide?

It's probably not a feasible solution to require these people eat healthy nutrient-rich foods due to economical and culture and personal choice reasons. Are vitamin supplements a feasible solution?

This is the reason that many breakfast cereals are fortified with vitamins and minerals.

It actually causes me to select otherwise "lower-grade" cereals than I might otherwise purchase. Fancier/healthier, more "natural", choices are not fortified.

Alternatively, a multivitamin intrinsically yields the same results.

Multivitamins don't seem to benefit people whose diets aren't especially terrible: https://en.wikipedia.org/wiki/Multivitamin (see specifically the 6 citations in the 2nd para)

> If I was filthy rich I would get nutrient levels measured once a week.

This sounds similar to what services like Viome (https://www.viome.com) do. Though, their intervals (at least Viome's) are much longer.

Damn. That's one of those "of course, why didn't I think of that", companies. Infuriating.

Really hope they're successful, seems like an unsolved problem.

Sounds helpful from the marketing text but pretty expensive.

If they could get that cheaper you could get people signing up out of curiosity. But when you see they want $200-$600 for this you start to get suspicious: what are you actually getting? Is it vetted by somebody? Etc.

> pretty expensive

Agreed. For whatever it's worth, I have a few friends who swear by it. I have no idea how dynamic our bodies needs are, but presumably you could make the price more reasonable by signing up, getting yourself on track, cancelling and then checking back in after 1/2/N years.

If so, and I think it is so, do capitalistic employers who employ highly paid employees (like software developers in the US) incentivize them (pay the cost and time to) check these things medically and get supplements etc? Brain fog and general sluggishness etc can directly impact the creative output of these highly paid professionals.

To some extent they do. I've worked at employers who prioritize diet (on site cafe's with posted nutritional information), exercise (on site locker rooms with showers, subsidized gym memberships and reimbursement for employee purchased exercise equipment), work-life balance, etc. I think at this point most employees would bristle a bit if their employer started providing on-site blood tests to check vitamin levels (Imagine the HN threads!), but I could see that changing if it became a more popular thing for people to do on their own.

These are also from recommended amounts which we have no idea what optimal is. Has there been studies to say what the blood levels of vitamin d etc. should actually be?

The scientific consensus tends to suggest a serum level of Vit D ~ 30 ng/mL as optimal. Bone abnormalities are expected with levels < 12 ng/mL. However, studies looking at serum levels in otherwise healthy individuals show most people at <20 ng/mL. My take on the reports is that you want supplementation if it's below 10 ng/mL, with diminishing returns past that. The supplementation required to achieve 30 ng, or even 20 ng/mL for most people probably isn't worth it, and with unintended health consequences. Brown and black people likely have significantly lower "healthy" levels that don't warrant supplementation.

> The supplementation required to achieve 30 ng, or even 20 ng/mL for most people probably isn't worth it, and with unintended health consequences.

[citation needed]

Safe upper limit is considered 4000 IU daily which will get you up there (and beyond) easily and is very affordable.

For comparison, spending a while in the sun with your upper body exposed is easily 10,000 IUs for a light skinned person.

> Brown and black people likely have significantly lower "healthy" levels that don't warrant supplementation.

[citation desperately needed]

Dark-skinned people are generally advised to supplement.

Like I said in the comment, this is my take on reports, not the current scientific consensus.

About the desperately needed citations, let's start from these two:

https://pubmed.ncbi.nlm.nih.gov/17413106/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6180659/

The first is a study in South Indians. Even among rural workers spending long hours in the tropical sun, the study finds >80% of people had Vit D levels below the 'sufficiency' level of 30 ng/mL, in this otherwise healthy cohort. 44% of them had levels below 20 ng/mL. While this study doesn't report bone density, other studies on rural Indians suggest the osteoporosis prevalence at ~ 1% of the non-elderly population. There are no long term follow up studies in the rural indian population, but it's a reasonable assumption that individuals with very low Vit D levels (ie, < 12 ng/mL) were more likely to develop osteoporosis later in life. The study also reports low dietary calcium and high intake of dietary phytate, which are suspected to reduce circulating vit D levels. Do these necessarily lead to long term harm? It doesn't seem like it. Other reports suggest that lower bone density among rural Indians is most strongly linked to lower lean muscle mass. Greater the load bearing exercise, the better the bone density.

The second study is among healthy blood donors in Nairobi, with 95% of subjects with Vit D levels between 12.73–22.07. In both studies, the participants live in tropical environments exposed to high levels of sunshine.

By setting the optimal level of Vit D at 30 ng/mL, it pathologizes these otherwise healthy subjects. The concern is that the long term supplementation required to achieve 30 ng/mL would have unintended consequences, such as inappropriate calcification. As the Nairobi study points out, while low levels of Vit D are linked high levels of parathyroid hormone, beyond a certain point increasing vit D levels are linked to higher PTH levels. PTH leaches calcium out of the skeletal reserves and raises calcium levels in the blood. The deleterious effects of Vit D hypervitaminosis are due to high circulating levels of calcium. The Nairobi study shows that the lowest PTH levels were associated with vit D levels ~ 30 ng/mL, while individuals with vit D of 50 ng/mL had PTH levels similar to those with Vit D levels around 15 ng/mL. From the figure in the paper, it looks like if the goal is to minimise PTH, vit D levels < 15 ng/mL are sufficient.

Which brings me to my initial assertion: brown and black people with plenty of sun exposure have naturally lower levels of circulating Vit D, with the average around 20 ng/mL. The Nairobi study points out that greater sun exposure did not significantly increase Vit D levels in this group. They do not seem to suffer greatly elevated levels of bone abnormalities due to this, or any other obvious health concerns. To me, this is suggestive that these levels are naturally equilibrated to be in the 20 ng/mL range, and attempts to push them higher might be deleterious. Setting the standard at 30 ng/mL unnecessarily pathologizes these otherwise healthy people, encouraging supplementation, which is not without health risks.

Dark skinned people who live in high latitudes probably need greater supplementation than their light skinned neighbours, which is reasonable.

Yes I'd like to see studies that show what happens if you have higher than 30ng/mL and if these people are on average are happier, fight infection better, lower cancer rate etc. I was saying in my comment we don't have the studies to back up that your 30ng/ml is 100% correct. Unless you can point to studies "scientific consensus" is merely hearsay.

To the point about scientific consensus:

https://doi.org/10.1007%2F978-0-387-77574-6_5

The authors suggest that 30 ng/mL seems like the sweet spot for most health outcomes. Higher levels (~ 50 ng/mL) might be beneficial for fighting cancer, but the risks associated with the prolonged supplementation is unclear, which is why they do not recommend it.

Something to keep in mind is that high levels of vit D are linked with high levels of circulating calcium, which is a problem. Protocols that advocate high Vit D doses, like the Coimbra Protocol for autoimmune diseases (100,000 IU per day), try to keep calcium levels low. The Coimbra Protocol tries to find the Vit D dose that minimises parathyroid hormone levels, and needs a diet practically calcium free to be safe. PTH causes calcium levels in the blood to go up, leading to kidney damage and inappropriate calcification.

Outside of an extreme setting like the Coimbra Protocol, while PTH is inversely linked to Vit D levels, beyond a certain point rising Vit D levels cause PTH levels to go up. This suggests that there exists a sweet spot of circulating vit D that minimises PTH levels.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6180659/

This study among healthy subjects in Nairobi found that the lowest PTH levels were associated with a vit D level around 30 ng/mL.

I’ve often wondered how we come up with daily dose recommendations for vitamins. To the HN hive mind/experts on this topic: What types of research design, data sets, etc. inform these recommendations? Essentially, is this well studied/well understood, and have broad consensus in the medical community?

And perhaps most of our conclusions are wrong (not b/c of our poor reasoning, but b/c we are misled by poor studies)!

Remember that half of all research papers are probably wrong and most of medical research is wrong, according to John Ioannidis:

"Why Most Published Research Findings Are False" by John P. A. Ioannidis:

https://journals.plos.org/plosmedicine/article?id=10.1371/jo...

Lighter reading on this topic:

"Lies, Damned Lies, and Medical Science" by David H. Freedman (who later wrote an excellent book on this topic, see below for link):

https://www.theatlantic.com/magazine/archive/2010/11/lies-da...

"A Researcher’s Claim: 90% of Medical Research Is Wrong" by Maia Szalavitz:

https://healthland.time.com/2010/10/20/a-researchers-claim-9...

And in these days of COVID, HCQ, Remdesevir, crisis, civil unrest and crime I cannot recommend enough David H. Freedman's book titled:

"Wrong: Why experts[1] keep failing us"

with the subtitle

[1]"Scientists, finance wizards, doctors, relationship gurus, celebrity CEOs, ... consultants, health officials and more"

https://www.amazon.com/Wrong-us-Scientists-relationship-cons...

Freedman examines thoroughly the issues that John P. A. Ioannidis has raised.

I think this is wrong: Ioannidis's major point is that a lot of studies in medicine are underpowered (a similar issue to the replication crisis in psychology), leading to a lot of false positives. But there is no reason to think that this would be the case for a study that finds a vitamin deficiency in the population. We can expect no issues with p-hacking or garden of forking paths just because there is no place for them (the researchers are not looking for crazy-small interactions between vitamin levels and one of many possible outcomes, they're just recording the vitamin concentrations), and we know roughly the right concentrations for those vitamins too.

So I think this is misplaced skepticism, you shouldn't really dismiss studies so easily without thinking through the issues first. This would be much more relevant if the research was specifically about some random compound's small effect on Covid-19 without a prior reason to think it would be relevant at all - then the problems would indeed appear.

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