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The survey in the article that assessed vitamin D deficiency was a bit odd:
>Because physical exams are performed in mobile vans in NHANES, data could not be collected in northern latitudes during the winter; instead data were collected in northern latitudes during summer and in southern latitudes in winter. To address this season-latitude aspect of the NHANES design, we stratified the sample into two seasonal subpopulations (winter/lower latitude and summer/higher latitude) before examining vitamin D status.
Yeah, I'm not surprised that the rates for vitamin D deficiency were low.
>Less than 1% of the winter/lower latitude subpopulation had vitamin D deficiency (25-OHD <17.5 nmol/L). However, the prevalence of vitamin D insufficiency in this group ranged from 1%–5% with 25-OHD <25 nmol/L /.../, even though the median latitude for this subsample (32°N) was considerably lower than the latitude at which vitamin D is not synthesized during winter months (∽42°N).
and the more northern latitude in summer:
>With the exception of elderly women, prevalence rates of vitamin D insufficiency were lower in the summer/higher latitude subpopulation (<1%–3% with 25-OHD <25 nmol/L)
Now imagine if you lived in northern Europe around the 60th parallel, where the sun doesn't get high enough in winter to produce vitamin D.
Not to mention, northern latitudes get more sun that average in summer, and most northern countries have more reasonable working hours so people actually do go outside.
This is why you're supposed to fatten up in the summer. In nature, mammals fatten up all summer long, and fat soluable vitamins such as D, are stored in your fat.
As animals basically slowly starve over the winter, they consume their fat and also get some vitamin D back. It helps shore up the lack of sun in the winter.
> Now imagine if you lived in northern Europe around the 60th parallel, where the sun doesn't get high enough in winter to produce vitamin D.
Like... all of Finland? And most of Norway?
Both countries where the answer to "when does the sun rise?" can be "at the end of January".
Could this be why evidence suggests that redheads synthesize Vitamin D more efficiently? Red hair is more prevalent at higher latitudes (I think).
Can redheads produce Vitamin D in these darker conditions while others cannot do so effectively?
https://www.sciencealert.com/evolution-favored-genes-linked-...
> data were collected in northern latitudes during summer and in southern latitudes in winter
And what were they doing for the other 9 months of the year?
I have made this comment on HN many times [0] now but: it's the goddamn sunlight.
Sunlight has many pathways in the body, and increased vitamin D levels are just one of those pathways. Swallowing one element of a many-element pathway cannot simulate the human synthesis of vitamin D! This should be obvious! Your car might not run because of bad needle bearings, but the solution is not to add them to the gas tank! First, you must always understand.
Sunlight / vitamin D is an especially aggravating issue because we have increasing amounts of research on how sun exposure improves general health. Sleep quality and regularity, mood, cancer incidence (as the article notes), eyesight, skin conditions, overall mortality, virtually every part of human health is improved by going outside. And when I say "improved" I mean improved to such a degree that it would blow 95% of prescribed drugs out of the water. See, for example, the Melanoma in Southern Sweden study where the highest sun exposure cohort had _half_ the all-cause mortality of the lowest group. Unfortunately the Western medical establishment is thoroughly captured by industry and you can't sell a pill that makes you go outside.
I think science is just too granular to be a reliable input into wellness decision-making. It is too easy for interested parties to enable everyday people to confirmation bias their way into defying common sense.
Of what utility is the truth in decision-making if it is such a narrow truth that it might as well be a falsehood in practice?
Alcoholics talking endlessly about flavonoids, obese people insisting in polyunsaturated fat mayo, sedentary people that don't resistance train drinking soda with protein in it.
Here in northern Europe, there just isn't enough sunlight to not become deficient, so a vitamin D supplement is a must.
Which could be one of the reason people near the Mediterranean sea (for example in Italy) and tennis players do tend to live longer than average. Now of course there s probably more than one reason but those sure do enjoy time outside.
Unfortunately, sun exposure (specifically UV exposure) is heavily tied to skin cancers and aging. I haven't researched it myself, but my feeling is that, ultimately, there is a calculation where sun exposure / skin risk needs be balanced on your specific genetic makeup.
We really need to drill down into ethnic and racial boundaries to really make sense of how much sun exposure helps us.
This is a refreshingly balanced and honest analysis of Vitamin D studies.
The strongest evidence for Vitamin D is in people who are severely deficient. Bumping up to a normal range can provide some improvements.
The health influencers started noticing that the Vitamin D studies coming out weren't matching their original hype for Vitamin D, so many pivoted to trying to make claims that most people are severely deficient and just don't know it, which provides a convenient out to dismiss the studies that didn't pre-filter for people who were severely deficient. You can find waves of people on social media repeating the idea that almost everyone is Vitamin D deficient and encouraging high dose supplementation still.
Speaking to a doctor who runs Vitamin D labs as part of her annual physical screening process, she's now actually seeing more people who have excess Vitamin D than too little Vitamin D. Upon followup she discovers that patients have listened to a podcast about Vitamin D and started taking it regularly, unaware that they're pushing their levels into the range where it can start doing more harm than good.
Vitamin D is tricky because it lasts for a very long time in the body, which means steady-state supplementation can take a very long time to stabilize. I suggest anyone supplementing for a long time get a blood test, which can be ordered without your doctor if you can't get your doctor on board.
On another topic: Fish oil has also gone through a similar cycle of being hyped up based on early results, with higher powered follow on studies showing much less interesting results.
Not in the field, but every time vitamin D studies come up I am reminded of the one that called out how current recommendations are based on faulty math (confusion on how to combine different sized studies confidence ranges ) and miss the mark significantly (and a lot of studies are based on those recommendations...)
Has anyone done a RCT of D3+K2? K2 seems to be important in the absorption of D3. Another aspect that bothers me with these studies is that we’re simply supplementing the vitamin D, seemingly without measuring the change in blood levels. I took 2000IU (+K2) a day for many years in between testing my blood levels and still had <30ng/ml and had to go up to 5000IU/day. I’d like to see some further study.
It's arguable whether Vitamin D is really a vitamin or a hormone, see
https://pubmed.ncbi.nlm.nih.gov/33549285/
Look at the molecular structure
https://en.wikipedia.org/wiki/Vitamin_D
that's a freakin' steroid with one of the bonds in the rings deleted
Even so, it still seems to be a small effect. The author mentions some studies looking at sunlight vs all cause mortality. These, and more recent studies [1] found much higher reductions in all cause mortality from sunlight exposure, of about 30%. It's thought that other factors may be behind this, such as NO production in the skin in response to UV [2].
[1] https://pubmed.ncbi.nlm.nih.gov/32918215/
[2] https://karger.com/bpu/article-abstract/41/1-3/130/328295/Su...
> For a while there, many people thought vitamin D was magical
I never heard that in Germany. I only heard that if you use certain medications like cortisone that vitamin d could be problematic. Most doctors will give vitamin d supplements when prescribing cortisone, at least in Germany.
I suspect that blood vitamin D is mainly a marker for how much outdoor exercise people are getting, and that it is the exercise rather than the D which is causal.
All I know is I used to have full on colds during winter in my 20s to early 30s, like every winter I would get two weeks of runny nose till the skin became red and irritated, sore and painful throat, coughing, etc. Since I take 25000 IU (D-Cure in Belgium) like 2-3 times a month during winter for the past 15+ years my cold last 2-3 days and symptoms are much more mild. For me the data is there.
Vitamin D is a biomarker of a process that happens in the body that is beneficial for longevity. This biomarker is created in response to receiving sunlight. The synthetic vitamin itself, does little, if anything, for your health. The process of receiving the sunlight is what benefits your health. This applies to a lot of other vitamin supplements as well.
So whilst you may be able to take a supplement to boost your vitamin D levels, the negative health effects of lack of sunlight are still going to occur.
I have HIV and am under treatment using medication, I have found D3 and K2 helps alleviate some of the side effects of the medication; largely my mood. Which makes a lot of sense because my immunity system is in constant daily activity.
However, I need to get more sunlight; I just don't think supplementation is the same as being in the sun. When I was homeless I never had these mood issues, but that's complicated, living day-to-day & meal-by-meal puts you survival mode so nothing is really past the hour.
All anecdotal, duh.
I think Vitamin D deficiency hype is driven by supplement sellers.
As someone who grew up in a European country where we don't get long summers, I suffered no demonstrable issues from the lack of sun nor did the many around me.
My family wasn't rich so food was reasonably nutritious but not perfectly balanced either.
Vitamin D supplements are sold widely, including in smaller supermarkets like Lidl and Aldi. And one imagines it all comes out of the same few factories.
There will be some who do need it, but not as many as are led to believe they do.
I experimented with D3 supplementation up to almost a decade ago. I made some HN comments about it [2018]:
https://news.ycombinator.com/item?id=17638508
I ultimately stopped it because it seemed to cause lower back aches. (Pretty sure, bone/muscle not kidney!) Every time I went on the D3, my back would start to hurt. That repeated several times, enough to suspect a pattern.
The cause may be similar to the itchy, tingling teeth.
According to this fascinating paper, Vitamin D can actually trigger the leaching of calcium out of bones, into circulation:
https://pmc.ncbi.nlm.nih.gov/articles/PMC8147670/
After the abstract, find the section heading "Vitamin D mobilizes calcium from calcified bone".
But that is in very high, pharmacological doses. Not your 5000 UI per day.
Another more recent trial (TARGET-D) is showing a 52% reduction in heart attack risk: https://www.empirical.health/blog/vitamin-d-heart/
That trial used a dynamically-adjusted dosage of a vitamin D3 supplement, where dosing was set as to keep blood levels within a target range of 40–80 ng/mL. IMO part of the reason this trial is showing better results than the previous clinical trials of vitamin D supplementation quoted in the above article is that vitamin D has bad effects if too low and too high. Adjusting the dose dynamically to achieve an optimal range gets you the benefits without some of the negative effects.
Your body needs vitamins in order to form complex aminos to operate. But your body only needs to make so many of them - especially if you are an adult, not pregnant, or not suffering from a disease of some sort.
The very premise that loading up your body with "excess" vitamins beyond what you need is already pretty fraught. Building a house without enough lumber can lead to long term deficiency - but loading up a construction site with more materials than are needed shouldn't automatically be assumed to be good.
The reality is that the modern diet has already solved so many common nutrient deficiency diseases (pellagra and goiters were a shockingly common diseases 100 years ago) that maxing out on vitamin intake has become more of something like a speculative hobby than anything else.
Thousands of words and no mention of the obvious thing - testing whether sun exposure is beneficial or harmful.
The article opens with the observation that southern states had lower cancer rates due to solar irradiance. But then we intervene by taking pills. Why not try to absorb through the skin, even if it means something like a tanning bed?
In case the author is here, you can find the Garland & Garland (1980) article on sci-hub.
And if link is allowed https://sci-hub.ru/https://doi.org/10.1093/ije/9.3.227
The charts showing vitamin D not helping, but also slightly hurting make the topic more relevant. The title is almost too flippant of the conclusions which is don't just take more than necessary,because it's likely to actively cause harm not just slightly increase your vitamin D.
I was told that there are lots of latitudes in North America where the sun is at too low an angle for your skin to make vitamin D for large parts of the year so you should take it during those times and then you should be fine during the summer if you get outside enough.
I don't understand why literally everyone I know are diagnosed with Vitamin D Deficiency. Even living in sunny California. Wasn't human biology adapted for it in the last 40k years? I understand we spend more time indoors, but literally everyone?
I didn't see any mention of K2 (or missed it) - but a lot of D supplements combine with K2 as a "traffic cop" to keep calcium in bones and not arteries. I've not found a ton of evidence on this either, but seems to be a popular combination.
Just because vitamin D supplements helps with rickets doesn't mean supplementation helps all the other things we seem to attribute to vitamin D.
I think a good hypothesis for the discrepancy regarding why people with "naturally" high levels of vitamin D fare better than those who do not has to do with how vitamin D is produced naturally.
If you take the vitamin orally it might help for rickets and a few other issues but if you take it naturally via sunlight you might actually be having other benefits that aren't properly measured today.
With the current state of fear surrounding sunlight I doubt people are getting enough to see benefits and all studies use oral supplements instead of time in sunshine.
I like this author but this post was only weakly intriguing.
More importantly, I'd like to know how long it takes to write a post like this.
Everything I write, I try to research and publish in under 2 weeks.
This post looks like it grew over time. I like that quality very much.
Leaving out skin colour from the conversations while mentioning 'randomized trials' and 'seasonal subpopulations' is problematic. Vitamin D production is highly tied to skin colour (melanin levels).
I started to take VitD on a whim and my mood and energy sure improved. Also I feel like I get sick less often. 3 friends whom I recommended VitD told me the same. Living in northern germany. YMMV.
> Because physical exams are performed in mobile vans in NHANES, data could not be collected in northern latitudes during the winter
Why not?
I was taking 4000IU of Vitamin D daily along with 100 mcg Vitamin K-2 MK-7. My Vitamin D level was 60ng/ml. I've since dropped down to 3000IU per day. I go outside a lot but am either covered or using sunscreen since I sunburn easily.
Early into the Covid pandemic, there was talk that vitamin D had some protective effect. Did this ever pan out into any kind of recommendation supported by evidence ?
I think taking a supplement every day is a good idea. I used to suffer from low vitamin D levels constantly until I started taking a daily vitamin D tablet.
> and it will still tell your bones to scavenge calcium... So the body scavenges a lot of calcium from your bones...
Bones take calcium from bones? Net effect 0 then?
I was told I was Vitamin D deficient and accidentally over indexed on supplements and got quite sick. Some of the dosages on OTC are ridiculously high
Vitamin D is a lifesaver for me. I'm severely deficient, and if I don't take about 10,000 IU a day, I seem to get colds every five minutes.
the Vitamin D RDA is too low at 800iu
but taking more than 2000iu per day is not just pointless but dangerous without blood testing
Vitamin D won't cure anything once there is a disease or illness
but it does show some preventative benefits
whole lotta people on Reddit do have blood tests showing it's way too low but those of course are the loudest voices
I rather liked his writing style - very easy to follow. He could have a future as a science communicator.
Vice versa, the exaggeration of vitamin D is mildly worthless. Some need supplements, some don't.
Probably heavily depends on the country/region, but here in Germany it is basically the norm to be Vitamin D deficient. Like, half of the population have a deficiency when there is some sun and basically everyone has a deficiency for months during fall/winter/spring. So I have to laugh when I read "taking vitamin D does nothing unless you’re severely deficient". Yeah like, but that's most people in many countries lmao
People who say vitamin d isnt important should read about auld rickie...