Uhm, how can you get to that conclusion? I mean: how can you compare the evolution of a cold with and without the vitamin surplus?
That said, do not underestimate the health benefits of the placebo effect. It can help a lot. Particularly with anything to do with stress.
It is my general understanding that unless you are severely deficient, Vitamin D supplementation generally takes weeks to bring levels up. It's unlikely that taking it for a few days is going to have any measurable impact on your recovery from illness unless you are severely deficient and/or taking MASSIVE doses, which may or may not be recommended depending on your prior levels and BMI.
See more here: https://www.ccjm.org/content/89/3/154
e: fixed broken URL
I've heard things like you only need 15 minutes of sunshine per day to get your recommended dose of Vitamin D, but I've also heard it can be quite bad for you if you have too much in your system (and it's hard for your body to flush excess amounts).
If there a safe level of Vitamin D supplements where you won't run this risk? I don't drink milk either because I'm lactose intolerant.
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
To help prevent vitamin D toxicity, don't take more than 4,000 international units (IU) a day of vitamin D unless your healthcare professional tells you to. Most adults need only 600 IU of vitamin D a day https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h...
So, I am not surprised that someone needs to take 5000 IU to get 600 IU worth of effect. Institutional medical authorities are (rationally) quite defensive when cautioning readers about supplement consumption; they must consider the worst case (100% bioavailability) when assessing the risk of overdose.
As an alternative to vitamin supplements, exposing common dietary mushrooms to ultraviolet light converts (by an uncatalysed photochemical reaction) the ergosterol therein to calciferol. How best to achieve this in a home setting is unclear.
This article, for example:
https://www.ccjm.org/content/89/3/154
...cites several cases where daily supplementation of 50K IU was required to restore normal D levels, although also a case where that same dose caused toxicity. As one of the other commenters in the thread noted, working with your doctor to establish the right level is probably the right move. If nothing else, they have the capability to test your serum levels to see where you're at.
I should note that I live in a place that sees little sun for five or so months a year.
Not medical advice here, but harmful effects from vitamin D exposure/toxicity generally only happen at very high levels, or if high doses are taken over long periods of time (as excess can be stored in fatty tissue/liver). Doctors often prescribe a very high dose (like 50,000 IUs) for individuals who are very deficient (often taken once a week, not daily) for a short period before going on a more standard (400-2,000, maybe 5,000) IU dose for maintenance.
Unless you eat the pills like candy, you're safe.
Although it'd be great if you explained what exactly happened, perhaps it wasn't a result of taking vitamin D itself but rather some external thing. Judging by "painful experience" I assume kidney stones, which could be caused by too much calcium or genetic preference. not a doctor or an expert on the topic though, just open for a discussion :)
Most people could probably take as much supplemental vitamin D as I did without incurring this adverse effect, but there is no straightforward way for a person to know whether they are in the minority of people who will incur the effect. (I do remember that having Northern European ancestry makes the effect more likely.)
The drastic wrongness started showing up after only a few months of whatever high dose of D I was taking (and I regret that I cannot provide this information: I did search for it briefly; but it was definitely not an "absurd amount") so if you've been taking the 8000 D3 for years, then the drastic wrongness is unlikely to suddenly show up in your case -- and if it does show up it would probably be because you contracted some sort of chronic infection.
The presence of certain kinds of chronic infections and genetics are the main causative factors according to the information I relied on 25 years ago. Actually, here is the basic information. I followed most aspects of the protocol including my obtaining a prescription for olmesartan, but then I lost interest when the drastic wrongness went away (after not much longer than 4 months IIRC). I was also probably on an antibiotic during this recovery.
https://mpkb.org/home/patients/protocol_overview
P.S., I take as much MK7 as you do (i.e., twice as much as the "suggested usage" on the label) and have for many years, just without supplemental vitamin D.
It should be part of your standard blood tests so you should know if you're running high or low and your doctor can recommend or prescribe a good dose.
I'm not a medical doctor. I cannot evaluate any of the above claims. I wish I could find a source I could trust.
The figure I read years ago was that it takes 15 minutes in short sleeves to get the necessary light exposure at the 45th parallel in winter. I'm right at the 45th parallel and I don't go out in short sleeves in the winter, so I imagine it's significantly worse for you!
That doesn't apply to you most of the time, unfortunately. Vitamin D is the result of UVB exposure. For significant portions of the year, you don't get very much [1], compare with, say, [2] Orlando Florida in the US. 10-15 minutes is for a UV index of 7 [3], so that's only 4-6 months out of the year for you. And just based on my couple minutes with Google here, that number may also include the assumption that you're not just "out in the sun" for 15 minutes, but basically sunbathing. Lesser exposure may take longer: [4] Winter times can be effectively impossible because you can't sunbathe at 10 below (regardless of which scale I'm talking about) and you're not going to spend the requisite hours in the sun for what little skin is exposed. Or they can be outright impossible if your skin is dark enough.
[1]: https://winnipeg.weatherstats.ca/charts/forecast_uv-monthly....
[2]: https://nomadseason.com/uv-index/united-states/florida/orlan...
[3]: https://overcomingms.org/program/sunlight-vitamin-d/uv-index...
edit: seriously though, anything warmer than -10C you'll definitely see kids in shorts. I go skiing in shorts every year.
Then again, most people aren't getting the equivalent of 15 minutes of index 7 UVB exposure at those temperatures, so it's not quite the same thing, but still.
Sadly, it doesn't say how long you should exposure yourself with a UV index of 1, which is what Winnipeg has today, and it's not even proper winter yet.
This can make dosing tricky. You can be taking an amount that is safe right now, but then is too much later.
You can max out your body’s vitamin D production even on a cloudy day, though the sun’s angle of incidence effects production.
The body typically maxes production at something like 20k iu (pleae verify this number it has been a while since I learned it), so staying below this number should mostly safe.
The USDA has set its recommended daily allowance mostly to avoid rickets. It is largely considered too low a number for general well being.
I live in north western Washington, and previously used to combat seasonal affective disorder, with some pretty dark thoughts come february. Since I started taking 1k D3 some 20 years ago much of the seasonal mental health has gone away. I take 2k D3 consistently currently, and if I run out for more than a week my mood starts to deteriorate quickly. I still haven’t proved causation since there are likely reasons I’ve let myself run out of the supplement that long, but it is so consistent that I treat it as causal at this point. YMMV
Please do research above just asking a forum for dosing advice though. This is a well educated place, and I would very much trust it as a starting point, but there is a lot of good published content on the topic. Though, I admit google is so bad today, I might fail to find any of the content I referenced years ago… if you use chatgpt make sure to require references, and check them. I find that using multiple instances to review research references separately prevents some context based poisoning as well. And pointing out inconsistencies can be a good way to find nuance in a topic. Though sometimes LLM will just waffle, and the context may be done
1 https://www.mdpi.com/2072-6643/17/17/2744#:~:text=highest%20...
2 https://www.abs.gov.au/articles/vitamin-d#edit-group-image--...
What would a diet poor in vitamin C be considering that "everything else" makes it? I guess root vegetables? It feels like, if anything, this would imply a GLO gene decay more often than has happened, no?
I have no opinion on the matter, and am inclined to think there is at least some positive benefit. But YMMV
If a 100 people take 50IU of Vitamin D, you get 100 different results.
Some get enough from minor sun exposure and maybe eating a fish now and then. Others need massive doses to get any results.
And yeah, it does not absorb well unless you eat some fat.
It took many months to get the levels back to normal. Vitamin D is one of those things that once you overdose, it takes many months for the levels to slowly come down after you stop supplementing.
Be careful with Vitamin D!
The downside to having high levels is plaque/calcium deposits in arteries, if I'm not mistaken. Which can be mitigated by taking K2.
Thanks for the tip though. I do not take it regularly so I think I'm fine. :D
> Treatment
> In almost every case, ceasing vitamin D intake, combined with a low-calcium diet and corticosteroid drugs, will allow for a full recovery within a month. Bisphosphonate drugs (which inhibit bone resorption) can also be administered.[2]
Regardless, blood levels need to be checked for this sort of thing and doses are not one-size-fits-all. I also once was taking 10k daily, for several months, and ended up just barely in excess territory with no noticeable symptoms. (I settled on taking 4k daily in the long term.)
That is what supplementing K2 with D3 is for, too.
All of the studies I've seen around Vitamin D supplementation has shown that the "safe level" reported today is way, way lower than it should be. People appear to be just fine taking 10k IUs for months on end, even 7 years in one study. I think what we're learning is that the "safe level" is a very wide spectrum; some people could possibly be harmed from a low level, whereas some people are perfectly fine at a very high level.
And some people, like those with MS (such as I) need to take more than usual. Someone I know has MS and takes 20k IU and gets regularly tested.
Whether it has a "positive impact" on overall health (which I believe to be your point), that would be even more anecdotal and also impossible for me to narrow down whether that one factor had any significant effect, so I won't posit that. And I agree that from different studies I've read, the actual science on it is pretty varied and I haven't seen anything conclusive. Even this study notes their conclusion was "... among adults with suboptimal baseline vitamin D levels".
I'm pretty personally convinced that it was the supplements that helped here.
I think I might try daily 10000IU after showing my doctor how little it's moving the needle for me
Proceed with caution and listen to your body. Doctors were accusing every other thing than accepting whatever it did to my calcium / other electrolytes bothered my heart.
I took a blood test several weeks ago, my Vitamin D level was 14 ng/ml. I was so fatigued there were times I had to lay on my office floor because I didn't even have the energy to sit in my chair. I started taking 50k IU's weekly and then 10k IU's daily, and the results were dramatic. I went from having 0 energy to nearly normal. I also had soreness in my legs which went away.
vi·ta·min /ˈvīdəmən/ noun any of a group of organic compounds which are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body.
https://www.thelancet.com/journals/landia/article/PIIS2213-8...
The meta-analysis you posted did perform subgroup analysis on people with low baseline vitamin D (<25 ng/mL), but this included a wide range of intervention levels, 90% of which were <2000 IU daily equivalent. They also performed subgroup analysis on high intervention levels, but this included a wide range of baseline vitamin D, 90% of which were >25 ng/mL.
Man keeps trying to bring the outdoors inside.
The UK also consumed a lot more liver than it does today I imagine...
With the industrial revolution there was a problem of kids in cities getting rickets. This was due to a lack of vitamin C and that was due to a lack of daylight due to the smog.
The solution was to take the kids out of the city so they could spend time in the countryside.
However, along with the industrial revolution came steam trains, and, with steam trains, it became a lot easier to get fresh food from the farm to the city table.
Milk became an early commodity for this railway trade, in the days before refrigeration. Bottling had to be invented too, along with pasteurisation to get the modern milk product. They fortified it with vitamin D and, in time, made it mandatory in schools for kids to have dinky bottles of milk for their morning break. All kids hated the stuff but it was 'good for them' and good for keeping farmers gainfully employed.
Then the clean air acts came along, with the first street to ban fires in fireplaces being opposite the smoke free coal factory, the factory being anything but smoke free. Deindustrialisation happened too, so there were no cities with smokestack industries at their heart.
With clean air there was no longer any need to fortify the milk with vitamin D, so that stopped. From now on, kids would get their vitamin D doing things such as playing in the school playground.
But then we became seriously car dependent and the age of the free-range child was over. With 'stranger danger' and screens (initially just TV) taking over, we entered a new era of people not getting enough daylight again.
Along the way vitamin D has been downgraded, much like Pluto, from being a 'vitamin' to being a hormone. A lot of people want to point this out and explain the science to you. From hearing how some talk about vitamin D, it sounds like the recommended supplements are all over the place.
Clearly there are millions, if not billions that seem to be living just fine with not much sunlight in their lives and on no vitamin D supplements. Where's the rickets? Good question, but then, in Antarctica, where there are months of darkness to endure, they are on something like 20,000 units a day, and they probably know what they are doing.
Maybe following their example for this winter could be my next 'nutrition experiment'. Sometimes, when there is so much conflicting information, it is best to do an n=1 experiment with one's own body.
Man want both good of indoors and good of out outdoors.
This isn't true of human doors; insects are very small.
We've had the technology to keep things in wax-sealed clay jars for quite a while, but I'm not aware that this was done with grain, where preventing spoilage would have been most valuable. Granaries are open to the air. (And devote quite a lot of effort to slowing the spoilage of the grain.)
If you wanted food that wouldn't rot, instead of keeping it in an airtight environment, you dried it.
If I have to survive the night, overhead protection and thermal insulation is more important than a fire. Source: I've tried using both without the other.
Shall we stop discussing any possible solution which might be out of reach for someone?
Walking in a forest is something that much of humanity can do, and it's not a particular privilege (in the pejorative modern sense) - even if there are a small number of people that have issues that would prevent this.
There has been minor improvement in controlled testing, but no noticeable benefit when actually trying to live life. I go outside near nature once each year as a test to see if there was any progress. I can’t tolerate much more than that.
Shots work well for some. They worked decently well when I was a kid, but these days, not so much. I still hope the current ones will work, as I don’t have other options, but I’m beginning to lose hope.
The practical man uses technology to offset the prison built for him. The hapless enabler farms “pithy” HN points in his LED-lit room.
Vitamin D therapy doesn't have such an effect.
There have been a number of people on HN who have attributed any measurable COVID benefit of Vitamin D, to a confounding variable, as recently as 3 months ago - https://news.ycombinator.com/item?id=44705486 The Big Vitamin D Mistake
As for it being a "scam" - there are enough valid studies that show what this one did, that folks who are deficient that are able to raise their levels tend to be slightly healthier.
There isn't necessarily evidence for supplementation beyond "normal" range, and I do agree that no one should just take high-dose vitamin D supplements without data (tests) that it is necessary.
I'm sure people who supplement or have good D levels also take care of themselves, generally - because they know D is one of the supplements that make a difference both somatic and psychological.
And thus do better with flu/cold.
As for magnesium, I would go with magnesium glycinate or magnesium threonate.
The big dose of D seems to help. I'm certain I'm deficient, since I already take 2-4k daily, which noticeably helpsy winter blues. It's the first time I can "arrest" a cold, and even if I get sick the symptoms aren't nearly as bad.
My full protocol for if I start feeling a cold is this:
1. 10k vitamin D 2. Stay extremely warm when I sleep. Uncomfortably warm. 3. Butyrate (probably a placebo) 4. Curcumin (almost certainly a placebo).
I take 2,000 IU per day, typically without a meal.
any reason why? it's fat soluble and absorbs much better if taken with a meal.
If you're optimizing your supplement stack, really gotta research each one individually (and how each impact the absorption of the others)
Be sure to take zinc with meals, or your stomach may hate you.
[1] "connection between vitamin D and the immune system through gut bacteria and may have applications for improving cancer therapies"
[2] "How the Gut Microbiome Affects Vitamin D Absorption"
[3] "vitamin D may affect the host-microbiota relationship."
[1]: https://www.science.org/doi/10.1126/science.adh7954
[2]: https://www.gutnow.com/medical-treatments/how-your-gut-micro...
-- Exactly 400 study participants recruited.
-- Exactly 193 of 200 participants completing the study in each group (which, for a study administered in a community setting, is an essentially impossibly-high completion rate).
-- No author disclosures -- in fact, no information about the authors whatsoever, other than their names.
-- No information on exposures, lifestyles, or other factors which invariably influence infection rates.
-- Inappropriate statistical methods, which focus very heavily on p values.
-- Only 3 authors, which for a randomized controlled trial involving hundreds of people in different settings with regular follow-up, seems rather unlikely.
"Assistant Professor, Department of General Medicine, Arundathi Institute of Medical Sciences, Dundigal, Medchal Malkajgiri, Telangana, India"
The 2nd author is listed here: https://aims.ac.in/general-medicine/ I did not find any trace for the other two authors (do they exist?).
Also, look at the timings: Received: 16-09-2025 Accepted: 29-09-2025 Available online: 14-10-2025
That's relatively fast but also the paper is not super in-depth.
And in general it seems like that the "International Journal of Medical and Pharmaceutical Research" is not quite well known. See the Editors, not even pictures there: https://ijmpr.in/editorial-board/
> Incidence of ARIs was documented through monthly follow-up visits and self-reported symptom diaries validated by physician assessment.
This is basically impossible to accomplish for 386 participants who aren't in some form of captivity (e.g. incarcerated, institutionalized, in the military, or a boarding school). Nobody cares enough to maintain a "self-reported symptoms diary" and make monthly visits for some study. If they actually ran the study as designed, they would've have zero usable participants even starting from 400.
Saying nothing of the ethics of giving half the Vitamin D deficient patients presenting at your clinic with a placebo.
That's a pretty big list. Add Retirement communities and your pool increases even more. Add to that the fact that this is India where the population is at least 5x bigger and much more concentrated..
Regardless, you can get a lot of data, but of it is from people who have other significant differences in lifestyle from the average person and so it is questionable how it applies. Military gets more physical fitness (we already know most of us need more). Boarding school implies young - children or just older, and so while not useful there are differences related to that to control for (military as well, unless you can get officers who are older thus allowing controlling for age).
Retirement communities in India are relatively new. Most older folks get taken care of at home by domestic staff, which, given India's demographics, are incredibly cheap and thus plentiful.
Shocker.
> The study protocol was approved by the Institutional Ethics Committee and registered with the Clinical Trials Registry of India
As far as I can tell, that registry is here: https://www.ctri.nic.in/Clinicaltrials/pubview.php
Doing a keyword search for the first author's last name reveals zero hits. (It's possible I'm missing—that search does not inspire confidence.)
The formatting/style and peer review history alone are enough for me to doubt this. Of course, the other users' points about study design and lack of transparency make it even harder to trust the claims.
"Vitamin D3, also known as cholecalciferol, is used as a rodenticide because it is highly toxic to rodents when ingested in sufficient quantities. It functions by causing a life-threatening elevation in blood calcium and phosphorus levels, leading to severe acute kidney failure"
"Despite its use in rodenticides, vitamin D3 is safe for humans and pets when consumed in normal dietary or supplement doses. However, extremely high doses of vitamin D3 can be toxic to humans as well, potentially leading to hypercalcemia, kidney stones, and renal failure. The difference in susceptibility between rodents and humans is significant; rodents are much more sensitive to the effects of cholecalciferol, which is why it is effective as a rodenticide."
The theory is that we are just poisoning ourselves by taking it and that our bodies react to being poisoned with the positive effects that are well documented and observed.
AbstractH24•7h ago
InsideOutSanta•3h ago
This does not mean that the same will happen for people who did not have a deficiency.
Having said that, there is good evidence that Vitamin D deficiency is widespread, and supplementation of Vitamin D is relatively safe unless you take excessive amounts.