Hacker News Reader

Comment by JohnTHaller | Hacker News Reader

About 45% of the US population has Vitamin D deficiency. It's higher among some populations (elderly as they are more likely to be home-bound, African American as darker skin inhibits UV absorption, obesity due to adipose tissue storage, etc). Those of us further North are more likely to be deficient as well due to decreased exposure during much of the year and being inside or bundled more in winter months.

View on HN

> About 45% of the US population has Vitamin D deficiency. It's higher among some populations (elderly as they are more likely to be home-bound, African American as darker skin inhibits UV absorption

I believe Vitamin D deficiency is defined by reference to a single level which is assumed to be valid for everyone. In reality, the level at which a deficiency is experienced almost certainly varies both on an individual basis and between racial groups. We say African Americans have higher rates of Vitamin D deficiency, but this is based on the assumption that their average levels of Vitamin D should equal those of European whites, not on an assessment of when they experience problems.

The better measure of Vitamin D deficiency would be "are there signs of rickets?", but somehow that never gets used.

Of course some believe that Vitamin D is a substance only required to prevent rickets, while others have assigned it all kinds of different roles so they would be unlikely to accept absence of rickets as a standard.

> Of course some believe that Vitamin D is a substance only required to prevent rickets, while others have assigned it all kinds of different roles

The phrasing there is a little weird. Conceptually you wouldn't expect Vitamin D to have the function "preventing rickets", in the same way that the function of Vitamin C is not "preventing scurvy". Vitamin C does several things, and the different failures of those different things manifest as different symptoms of scurvy. Scurvy is what happens when you don't have enough Vitamin C, as rickets is what happens when you don't have enough Vitamin D.

Rickets is one of the things that can happen if you don't have enough Vitamin D. Other less obvious things can happen as well.

Migraines and autoimmune issues are related heavily to Vit D.

> [...] the function of Vitamin C is not "preventing scurvy"

Ironically, its scientific name, "ascorbic acid" means precisely that: no-scurvy (a-scorbic) acid

So are you claiming that there is something biologically different about the different races that means their normal biochemistry differs between one another?

> are you claiming that there is something biologically different about the different races that means their normal biochemistry differs between one another?

Yes, genetic variations meaningful to e.g. certain drug responses [1] correlate with race.

Fair question which, if asked without malice, doesn’t deserve a downvote.

[1] https://pubmed.ncbi.nlm.nih.gov/17329986/

Advice about healthy sun exposure to ensure adequate Vitamin D production generally notes that more exposure is required if you have Melanin in your skin (i.e darker skin).

https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-...

"If you have dark skin – for example you have an African, African-Caribbean or south Asian background – you may also not get enough vitamin D from sunlight."

That is already being studied between genders [0] as there are drugs that interact differently between men and women.

Even though the racial aspect of it can be taken a bit to the eugenics side by bad actors I believe that more studies should be performed to assess if there are or not significant physiological differences to account for during medical development.

[0] https://medicine.yale.edu/news-article/11874/

Why wouldn’t there be variation depending on the genes and the phenotype of a population, which can be correlated with skin color? Talking about « races » on the other hand is not neutral.

Population groups, not races.

Skin colour is a poor dividing line between populations, though maybe on this vitamin D issue it might be more reasonable. There is no "black race." There are populations of various African origins, a much more complex and messier situation that the category "race" obscures. There is statistically more genetic diversity _within_ Africa than in the entire human population outside of Africa, so drawing a cline based on some "black" or "African" or "Negroid" basket of traits is fully 19th century quackery.

EDIT Put another way: "race" is a cultural category, with little biological meaning. The key question here is vitamin D responses in southern-adapted vs. northern lattitude adapted population groups.

"Race" is a fairly modern concept that bares little if any association with actual biology.

> We say African Americans have higher rates of Vitamin D deficiency, but this is based on the assumption that their average levels of Vitamin D should equal those of European whites, not on an assessment of when they experience problems.

Couldn't you just survey average vitamin D levels in native West African populations, and compare it with African Americans?

Even if there was a difference in the requirements between native Africans and native Europeans, many African Americans also have varying levels of European heritage that would complicate the picture.

Off the top of my head, I'm not familiar with Vit D surveys in West Africa, but there have been some in East Africa. From these, it looks like lifestyle and diet are probably the biggest determinants of Vit D levels. For example, the pastoral Masai have phenomenally high levels of Vit D, while a related tribe of agriculturalists have significantly lower levels, with similar sun exposure. Another survey of young healthy urban participants in Nairobi found similarly low to mid levels of Vit D. Among South Indian rural farm workers, who have complexions comparable to the African subjects and similar levels of sun exposure had much less levels of Vit D. It was speculated that phytates in their diet impacted Vit D levels.

The thing to keep in mind here is most illnesses deplete the body of Vitamin D during their course.

So you would actually need more data on whether these people were deficient before they got sick with COVID.

Exactly, and they don't get much sunlight while in a hospital

The article wasn’t very detailed and I wasn’t able to figure out if you are more likely to catch COVID because you have a vitamin D deficiency or if catching COVID causes a vitamin D deficiency. Anyone know?

The former as there is no known way that Covid reduces vitamin D

Staying home or in a hospital bed without sufficient sunshine exposure (which will likely happen to anyone feeling sick) will reduce vitamin D levels.

I don’t know what you consider “known way”, but this Hypothesis is mentioned in almost every discussion, and is not controlled or corrected for in any study I’ve seen.

(There is reason to believe vitamin D Supplementation is helpful, based on earlier studies related to viral respiratory diseases - but not yet enough data specifically for covid)

That is false. Get enough vitamin D and it can stay in your system for months. Going to a hospital for a few days will not effect your levels.

The previous articles I read about Vitamin D & Covid (mentioned in German and Swiss news, not sure about the location of the cases) were related to critical cases in hospitals.

Meaning that if the conditions are right (e.g. area having a high virus density, long exposure to low levels, whatever...) you might anyway "catch COVID", but if your vitamin D level is OK then you might be less likely to end up in an hospital or even in intensive care (because by having good vitamin D levels your body can apparently fight better against the virus). I think that none of the stats showed an absolute confirmation of this data.

Therefore, in my opinion, your sentence/question is a huge misunderstanding, but of course I might be wrong :)

> but if your vitamin D level is OK then you might be less likely to end up in an hospital or even in intensive care

But only as a form of correlation not necessary causation.

Which means if you make sure you don't have low vitamin D levels because you heard it is correlated with COVID your likelihood of having worse COVID systems might not change at all!

Becau you might have "something" which makes worse COVID systems more likely which also happens to cause low vitamin D levels. Or you might have something caused by your living habits which also makes low vitamin D levels more likely.

I.e. as far as I know studies could only find statistic relevance for correlation (in some cases) but no statistic relevance for causation.

Idk, but it might literally be as simple as unhealthy older people being more likely to have vitamin D deficit and also being more likely to have worse COVID syntoms.

If you ignore the extensive literature describing vitamin D's multi-pronged involvement in metabolism then your final sentence is entirely reasonable. Here's a very short summary of some of the effects whereby vitamin D may may be causatively involved in the strongly demonstrated (there are numerous accounts in the literature) inverse relationship between vitamin D levels and the severity of COVID infection. Incidentally the focus should be not on how much vitamin D is taken as a supplement but on the actual blood level. Tons of references on what this should be rather my quoting those levels here.

https://www.alliedacademies.org/articles/potential-mechanism...

Thanks, I realized myself that what I wrote is flawed.

Even ignoring the literature you linked and just using common sense having a deficit puts a burden on your body and any additional burden when fighting some illness makes the fight harder. (Well, ok, there are some exceptions, humans are complex.).

Sorry, I think that I didn't understand anything - what's your and [vixen99]'s conclusion?

I would imagine being in a hospital bed for days without sunlight because you're sick with covid could result in a reduction of vitamin D.

Reasonable.. calcidiol (25-hydroxyvitamin D3) has a half-life of about 15 days in the human body.

D3 is also stored in fat, and released as fat is metabolized.

doubtful, the body stores vitamin d in fat cells and individuals that have have sufficient levels will also have some stored up. Vitamin D levels in the blood don't work like an on/off switch depending on how long you were in the sunlight on a specific day or even week.

From other articles and study abstracts I read, it seems that an existing vitamin D deficiency is correlated with worse Covid-19 outcomes (worse symptoms, higher levels of death).

This particular study found no causation

> No causal relationship was found between vitamin D deficiency and COVID-19 severity as a combined endpoint or as its separate component

That doesn't mean what you (and possibly they) think that means.

Suppose that characteristic X (eg vitamin D deficiency) puts you at risk of doing worse at Y. If we pick a population based on how poorly they do at Y, we expect to see that X will be more common than it is in the general public. But within that population there is no reason to believe that having characteristic Y makes you do worse - it just made you more likely to do badly enough to be selected.

This can be seen quite precisely with a toy model. Suppose that we have a population evenly split between 2 subpopulations with a characteristic that varies on a normal distribution. However one population averages 1 standard deviation worse.

If we pick the bottom 5% of the population on that characteristic, we will find about an 80-20 split based on having the risk factor. The bottom 1% also has the same 80-20 split. Ditto the bottom 0.1%, 0.01%, and so on. The reason is that the sum total of how many are in the tail of the normal falls off exponentially fast, with the same exponent in both populations. So the ratio stays constant.

No amount of analysis of people in that tail will suggest that characteristic matters. But comparing the population in that tail to the general population, that standard deviation stands out like a sore thumb as a major risk factor.

Therefore the fact that about 50% of the general population has vitamin D deficiency while over 80% of those hospitalized with COVID-19 do suggests that vitamin D deficiency is a risk factor. But we should draw no conclusions from the fact that vitamin D deficiency doesn't indicate different outcomes within the population landing in the hospital.

(However other research found that patients given vitamin D once landing in the hospital were significantly less likely to wind up in the ICU or dead. We should definitely draw some conclusions from that!)

The paper found no relationship between vitamin d and the severity of the disease

To your question, either outcome is enough for you to optimize a diet or activity with adequate amounts of vitamin D because the process is healthier either way unless you were thinking to just try taking supplements

You're missing the third option:

People who are more likely to be hospitalized due to COVID are also more likely to be deficient in vitamin D. There doesn't have to be a causal relationship at all.

I understand what you mean, but don't think your example really fits since an increase in vitamin D in either scenario would ultimately reduce the occurrences of patients showing low vitamin D levels. And this seems to be a fairly consistent finding across multiple studies that use different controls/stratification/etc.

Or do you mean people may be becoming deficient in vitamin D as a result of Covid? If so, would be interesting to know their prior vitamin D levels.

I'm not entirely sure you're replying to the correct comment, but just in case...

I mean the population of people who are more likely to be hospitalized due to COVID also happens to be the population of people that is more likely to be deficient in vit D, and neither of those things have to cause the other.

An increase in Vitamin D levels may or may not impact COVID 19 hospitalization rates.

Just like lowering ice cream sales won’t change the murder rate. Even though increased Ice cream sales is correlated with increase murder rate.

I know your point is that correlation does not mean causation (though maybe those are correlated?), however, that really makes it sound like guys like Ben & Jerry have blood on their hands.

rblatz is referring to a well known correlation: more nursery happen in summer. More ice cream gets sold in summer. Therefore, ice cream sales are correlated with murders.

This correlation is not random - it holds across geographic boundaries and time. But it is not causal - decreasing ice cream sales (By limiting supply, raising price, etc) will not reduce murders. Decreasing murders (By more police intervention, limiting arms sales) does not reDuce ice cream sales.

Similarly, vitamin D may be The ice cream analog. COVID 19 may be the murder analog, and if that’s true, we don’t yet know what summer’s analog here - could be obesity, or genetic factors, or something else. We don’t know.

typo - you put 'nursery' instead of 'murder'

Thanks, too late to fix now. DYAC, was on phone and didn't notice.

> Even though increased Ice cream sales is correlated with increase murder rate.

I thought you were kidding but no: https://slate.com/news-and-politics/2013/07/warm-weather-hom...

^this!

I suppose there's even a fourth option:

People who are more likely to be hospitalized are also more likely to be deficient in vitamin D.

The control group seemed to be a healthy population sample, but hospitals are not a pool of healthy people. How about a hospital sample instead of a population sample?

Maybe Vitamin D reduces all-cause hospitalization

Maybe beeing healthy and able to go outdoors reduces all-cause hospitalization (apart from accidents)

Or maybe low vitamin D levels are a symptom of the same "root cause" that leads to higher risk for Covid-19 and just supplementing vitamin D does not do anything to lower the latter.

Those vitamin D level statistics have been floating around for months. What's missing is a placebo-controlled study to see whether supplementation would make a difference. But that involves more than just clicking a bit of statistics.

That study is absolutely not missing, and it says exactly what you'd expect it to[0]. It's even being tested as an active treatment[1]. In fact, that study was also done with Influenza[2] and other lung borne ailments as well. It pretty obviously works, has tremendous explanatory power in the observed patterns of disease, and the fact that no government has sanctioned its use or its mass production ... well, I guess modernity kind of sucks. Better to pimp useless expensive garbage pharma companies can turn a profit on.

[0]https://clinicaltrials.gov/ct2/show/NCT04536298

[1] https://clinicaltrials.gov/ct2/show/NCT04385940

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4463890/#:~:tex....

Excellent, thank you.

Unfortunately, [0] and [1] are still ongoing and [2] reads like a blog post of somebody ranting about a statistical error, followed by some anecdotal evidence and the demand for an actual study. There could still be something there, but summarizing all of that as "quite obviously works" is stretching it.

Or maybe a 5th option: "People who are staying socially isolated spend less time in the sun, so the population has become more vitamin D deficient".

I know that I'm spending less time outdoors than I used to -- no more outdoor picnics/parties, no beach time this summer, I'm not even biking as much as I used to.

Or a 6th option: Over 80% of people have Vitamin D deficiency, and the incoming Covid-19 patient population was not different in this regard.

I don't know of any post-COVID studies, but most studies pre-COVID show around 40% of the population being deficient both in the USA and Europe.

This, and as someone who recently found out that they have a severe vitamin D deficiency, I was surprised to know that it's not something normally checked for in yearly blood tests.

Check the videos on Dr John Campbell's (PhD nurse educator in the UK) web site. The UK national health service has good medical records that can be cross-referenced and cross-linked every which way. Someone examined the historical records, found a reasonably large number of persons who had vitamin D levels checked before the pandemic, and checked those statistics vs the Covid-19 experience of the same people. (Imagine living in a country where that could happen.) IIRC, this did find some benefits wrt COVID-19 of not having a very low vitamin D level.

This isn't really a 7th option because it overlaps with some of the previously mentioned ones, but perhaps individuals who don't supplement with vitamin D are more likely to catch Covid-19 because they also don't take other precautions like wearing masks.

Anecdotally it seems those I know who are most concerned about Covid-19 know all about the possible link with vitamin D and are taking supplements while also being careful by wearing masks, sanitising etc.

Recently I keep seeing references to protecting oneself by wearing a mask.

When did the narrative shift from "wear a mask to limit transmission to others in case you might be infected and asymptomatic" to "wear a mask to protect yourself"?

Assuming we are talking about the usual surgical / cloth masks here (not N95 etc), is there any evidence that they protect the wearer?

We all know that mask wearing and the science (or lack of it) to support it has become ridiculously politicised, but I'm curious if there's any evidence behind this particular shift.

There is some weak evidence that wearing a cloth mask might protect yourself:

https://www.businessinsider.com/56-got-coronavirus-south-kor...

https://www.npr.org/sections/health-shots/2020/06/21/8808322...

There were results from studies showing weak effects of self-protection even by "simple" surgical masks a few months ago.

Evidence seems to indicate there is such an effect - and contradicting the initial assumption that there isn't.

That would be incorrect. Even though the causal vector is unknown, the correlation is well established.

But that actually contradicts logic a bit.

I would expect those that are leaving their homes are both more exposed to sun/less deficient in vitamin D and also more likely to contract COVID.

And likewise, those that are staying home are more deficient, but less likely to contract COVID.

Unless social distancing in practice is not uniformly effective, and a large number of people both stay indoors to social distance, and are still quite likely to catch COVID because they are indoors with people who don't socially distance.

Plus being indoors means a confined space with less airflow, less air volume, and almost no upper range UV sunlight compared to being outdoors; these all are significant factors for likelihood of covid spreading.

Uhm, that seems a tad convoluted. Are you saying people that socially distance themselves are more likely to contract Covid-19 because the ones that don't are so often outside that they will contract it less probably?

And further, that's not the definition of social distancing. This would obviously include indoors. I won't sit at my kitchen table with the postman for a coffee while I am avoiding public gatherings.

I am sorry, my sarcasm-radar is quite broken. Are you joking?

How would this produce the study result?

Are people that isolate more likely to get hospitalized with Covid-19 than those that do not?

I doubt anyone is saying with 100% assurance this is the -cause- but that it would be worth investigating further. If they'll change FDA recommendations for the blowhard in chief, we should also consider lack of certain nutrients as possibly something to look into as well.

I recall an article a few months ago that discussed the Vitamin-D link in more depth, and a plausible mechanism was already suggested: vitamin D regulates the immune system response. People with low vitamin D levels are more likely to experience severe cytokine storms.

PDF from April 2020: https://www.medrxiv.org/content/medrxiv/early/2020/04/10/202...

The impact of Vit D in enhancing immune response (including flu and previous coronaviruses) has widely been studied and firmly established. Vit D can also suppress cytokine storm, which may substantially increase the chances of avoiding a severe case of COVID-19

Yeah, that's very likely actually, since the biggest risk group, the elderly, are also one of the groups with the highest levels of vitamin D deficiency.

In this study here 84% of the elderly had some amount of vitamin D deficiency (Figure 3).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6178567/#:~:tex....

I do take Vitamin D supplements since they're cheap and available, just in case there is something to it, but I wouldn't bet on it.

I do the same. Getting enough sunlight is hard during wintertime.

Vitamin D deficiency has been linked to compromised immune systems, depression, rickets and several other things. More research is needed within several of those areas, but I believe it to be safe to assume that supplementing with vitamin D is good for you if you're deficient. If not, well, it's not like it's going to hurt you unless you overdo it.

There must be very well controlled groups of elderly people who after some blood test have been taking supplements and checking their vitamine D levels. I wonder how the virus is affecting this group compared with the general population of the same age. If this group were doing well, I think it would be quite conclusive, since it would show that people under treatment (and therefore with some previous health problem) are doing better than supposedly healthy people with low vitamine D values.

The level of evidence isn't great yet, but its highly likely that Vitamin D can help modulate the immune system. There is a retrospective study showing a difference between patients that got Vitamin D and those that didn't (can't find the link, unfortunately), and

there is a small Spanish trial of 75 people where 50 got Vitamin D and 25 did not; in the group that did, 1 person needed oxygen whereas in the other group 12 people needed oxygen and one died - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456194/

Since vitamin D is cheap and readily available, we don't need to wait before making sure we have enough of it.

Grip strength is another proxy for health, specifically how likely you were to die anytime soon. Makes sense. But training your grip won't make you live longer.

Still taking the vitamin D tho...

Are you saying that we can correlate general health to vitamin D levels?

Yes there is some correlation. People who are generally healthy tend to spend more time out in the sun.

Given enough data we can correlate pretty much anything to anything

Have you actually done (or read) a study to show that grip training doesn't increase lifespan?

I think one would look for a mechanism for how that could work. "How could grip training increase lifespan?"

I can't think of a mechanism for that effect, where something else wouldn't be probably better way to spend that effort. Like cardio training.

"Hypertension markedly increases the risk of cardiovascular diseases and overall mortality. Lifestyle modifications, such as increased levels of physical activity, are recommended as the first line of anti-hypertensive treatment. A recent systematic review showed that isometric handgrip (IHG) training was superior to traditional endurance and strength training in lowering resting systolic blood pressure (SBP)"

-- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5807761/

That is WILD. Thanks!

There is a considerable volume of literature indicating a positive correlation between daily vitamin D supplimentstion and reduced respiratory infections. The quality of the studies isn’t great, but generally a positive impact was found for small doses, especially for children.

AFAIU, catching any illness is likely to reduce your vitamin D levels. For one thing, the active metabolites are created by the liver and then the kidneys. https://www.cdc.gov/nutritionreport/99-02/pdf/nr_ch2b.pdf Illness can depress this process. See, e.g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6360762/ Furthermore, if you're bed-ridden then you're not likely getting sunlight, and it only takes a day or two of no sunlight for your serum levels to drop significantly.

Of course, none of this is to say that there's no reverse causative relationship as well, but people really need to take these correlation observations with a huge grain of salt. And also take note of extremely inconsistent results when controlled trials are attempted.

A slight technicality that I only recently learnt. You catch a virus . In this case it is Sars-CoV-2 . The virus causes a disease. In this case Covid-19.

So , how this ladders up (in my understanding at-least is this): People can catch the virus irrespective of Vitamin D levels. The virus can and will replicate in the body. The Vitamin D levels in the body determine the severity of the disease in the said body. This all feels intuitive but I am conscious that immunology is where intuitions go to die so someone please correct me if I am wrong :)

The studies with positive results are suggesting somewhere around a one binary order of magnitude reduction in risk of infection with possibly some reduction in severity of cases. I'd suspect that the health authorities would not be reluctant to promote a vaccine that had similar results if none better becomes available. Some hospitals are supplementing vitamin D for Covid-19 patients. Trump got it.

It is interesting that with this much evidence, public officials are not telling us to take VitD.

The masses are crazy though - VitD can be a little dangerous and I can see quite a lot of people taking '10x doses' to get '10x protection' and ending up in the hospital anyhow.

I saw an article posted someplace a couple of weeks ago telling the story of one person who suffered from too much VitD -- but that person wound up in the hospital only after taking 78000 units/day for about 8 months. That article would have been misleading then if one inferred from it that you really have to seriously knock yourself out to do any damage?

The answer is simple: It's unclear, because the study design they did cannot answer such questions.

This is one of the most basic misunderstandings in interpreting scientific studies. If you have "we saw x where we also saw y" then it can mean anything from "x causes y" to "y cause x". And also "unknown factor z causes both x and y", "it's a random coincidence", "they looked into the data long enough with enough different methods to find something" or a combination of all of those.

I assume the elderly would have higher rates of deficiency due to being indoors more, and that 45% number is also out of date during the pandemic when a lot of people are staying home.

The deficiency doesn’t have to do with being indoors. It has to do with how their body functions and absorbs sunlight. If the 45% number is low because of the pandemic itself then we wouldn’t be seeing such a huge decrease in deaths from the disease if it were a major factor.

Or perhaps being stuck inside without sunlight for a few weeks after being afflicted with a serious covid case, may cause vitamin D deficiency?

How long does vitamin d, as produced by exposure to direct sunlight, stay in the body?

Half-life of 15 hours or ~15 days depending on the variant [1].

[1] https://www.uspharmacist.com/article/vitamin-d-supplementati...

Right. To clarify half life means the rate it divides in half so after 15 days about half of what you took 15 days ago is left, after another 15 days half of that is left or 25 percent of the original amount, and so on. So it stays in the body for months if you get enough vitamin D.

Reply on news.ycombinator.com