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I've mentioned this before, but my wife is a parathyroid surgeon (parathyroids are the glands that regulate the calcium in your neck) and would beg you to PLEASE monitor your calcium levels if you are supplementing with Vitamin D. She often sees patients on high doses of Vitamin D from well intentioned doctors, but with out of whack calcium levels because of it, and the patients can be very sick without understanding why. Often their doctors don't understand the processes either which is why they end up with her. I'll have her write a blog post about it at some point, but it is a real risk with possible severe long term consequences and she sees it a lot more often these days. She is getting her blog kicked off here (just yesterday actually) https://devaboone.com if you want to follow along.

Would you mind elaborating on what you mean by "wacky" levels? I can't tell from your comment if that means high or low. Asking as a Vitamin D supplement user who uses 2-3k IU a day

Hi, I'm the wife. High dose Vitamin D can cause elevated calcium levels (meaning over 10.0 mg/dl for adults over 40, it can be a little higher for younger adults). I usually don't see that occur with doses at 2-3 K IU daily. You can also check your Vitamin D 25-OH levels (the level that will be done if you just get a standard "Vitamin D level") and these should be in a reasonable range. What constitutes reasonable may be debatable, but in general I do not see elevated calcium levels with Vitamin D levels that are under 50 ng/ml (unless the person has parathyroid disease, another topic). The "toxic" range for Vitamin D is usually set to 100, but this is well over where most people should be. Toxicity with regard to Vitamin D means high calcium - that is the toxic effect. And I have seen this toxic effect occur with Vit D levels in the 50s.

Would you still consider 5,000 IU of Vitamin D per day safe as far as these calcium issues go?

I had a doctor tell me to take that dose for at least a few months a few years ago after low levels in my bloodwork during the winter. But I've never known if I should lower the dose to take on a continuing basis or adjust during the summer when I get a little more sun (but I still work in an office/at home so spend a lot of time indoors, especially now).

I do see people get high calcium levels after being on this dose for years. But not always. You may be able to handle that dose. If you are getting "routine" labs done, then there is likely a calcium level in there. If your calcium is normal (under 10.0 mg/dl for adults over 40, younger adults can be a little higher), then your Vitamin D dose is ok... but I would still recommend coming down a bit on that dose. It is a high dose, and Vit D builds up in your body, since it is a fat soluble vitamin.

Curious on your thoughts/experience with dosing w/ co-factors wrt to calcium levels (for patients, have you been tracking these?)

Specifically, Vitamin K:

Ballegooijen, Adriana J. van, Stefan Pilz, Andreas Tomaschitz, Martin R. Grübler, and Nicolas Verheyen. “The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review.” International Journal of Endocrinology 2017 (2017). https://doi.org/10.1155/2017/7454376.

And Magnesium:

Uwitonze, Anne Marie, and Mohammed S. Razzaque. “Role of Magnesium in Vitamin D Activation and Function.” The Journal of the American Osteopathic Association 118, no. 3 (March 1, 2018): 181–89. https://doi.org/10.7556/jaoa.2018.037.

I'm also curious on your thoughts on what you consider high for supplementation, vs say sunlight exposure, as a single MED of sunlight exposure is equivalent to about 10-25K IU of oral supplementation.

Engelsen, Ola. “The Relationship between Ultraviolet Radiation Exposure and Vitamin D Status.” Nutrients 2, no. 5 (May 4, 2010): 482–95. https://doi.org/10.3390/nu2050482.

On the flip side, I've seen that in a recent RCT, that recommended sun exposure guidelines were not sufficient in reversing deficiency:

Lee, Yu-Mi, Se-A Kim, and Duk-Hee Lee. “Can Current Recommendations on Sun Exposure Sufficiently Increase Serum Vitamin D Level?: One-Month Randomized Clinical Trial.” Journal of Korean Medical Science 35, no. 8 (January 22, 2020). https://doi.org/10.3346/jkms.2020.35.e50.

A couple of questions if you don’t mind.

What are your thoughts on the research about low Vit D being caused by inflammation as opposed to the reverse?

Also any thoughts on what form of testing works? Seems like many things tested often have variations that are not routinely tested for.


My autoimmune disorder was initially diagnosed via positive responses to antibiotics. Normal testing confirmed it later on, so I’ve been highly interested in some of these unusual approaches.

just checked my "Vitamin D, 25 OH" test:

result: 13.3 ng/ml, normal range: 25.0 - 80.0 ng/ml

I'm taking Vitamin D3 Max 125MCG per day, is this "overdose"?


Since the doc hasn't replied to this question (yet), your Vit D levels are low enough to warrant supplementation. In my country it is common to supplement with 60K IU once a week, for 8 weeks, before moving to a maintenance dosage of 60k once a month. That's almost 10k IU/day during the loading phase. You're at 5k IU/ day, so should be fine. In comparison, a fair skinned person at the beach on a sunny day will make over 10k IU of D3.

Thank you!!!

The Harvard Gazette:

Study confirms vitamin D protects against colds and flu


This is entirely anecdotal, and I don't have an expert's opinion on this, but I believe I was suffering from Vitamin D toxicity. I had been taking 5000 IU/125 mcg of Vitamin D3 daily for several years, and one day I started experiencing painful and distressing heart palpitations. They persisted on and off for months, until at one point near the beginning of quarantine I ran out of Vitamin D supplements. I went a few weeks before buying more, and during this time I didn't have any heart palpitations, though I hadn't really noticed until after I started taking Vitamin D again, at which point my heart palpitations restarted immediately. I stopped taking Vitamin D and haven't had any heart palpitations since (several months now). My working hypothesis is that the Vitamin D supplements were causing heightened blood calcium levels, which was messing with my heart.

Fairly likely you are magnesium deficient...magnesium is a critical cofactors to vitamin D and even moderate D3 intake can trigger symptoms such as muscle cramps and heart rhythm changes. Unfortunately no easy way to accurately test a magnesium level, as it’s mostly intracellular and blood tests are pretty much useless

Possible, but I think unlikely. These days, my diet mainly consists of Soylent and Vite Ramen, which together provide me with 105% of my DRV of Magnesium in the form of Magnesium Phosphate and Magnesium Gluconate, respectively.

Looking at the nutritional info for Soylent and Vite Ramen shows that they also contain Vitamin D - at the same DRV percentages.

If you're getting 105% of your magnesium from these items, then you're also getting 105% of your Vitamin D before taking any additional Vitamin D supplements/sun exposure.

Adding the 5000IU of Vitamin D3 would be increasing your intake to 5840IU (730% of DRV) - assuming you didn't ingest anything else fortified with Vitamin D.

Not a single person knows what optimal Vitamin D or Magnesium means for the population or for you individually. So it’s very difficult assumptions here, even with testing genetics plays a huge factor.

Great answer, thanks. So measuring blood levels of vitamin D and setting a specific target no higher than 50 ng/ml should be enough to avoid this problem for most people? Or could taking a high daily dose for a short time to get to the desired blood level cause trouble as well?

Finally, do you see much difference in getting to that high blood level of vitamin D from sun exposure vs D in diet (fish, etc) vs supplements?

I recently started trying to get more vitamin D from the sun, a sperti vitamin d lamp, and food, in order to reduce the amount of pills needed for a given IU. I use the dminder app to track estimated blood levels between tests.

Some people can tolerate Vitamin D levels above 50, so I wouldn't set that as an absolute cutoff - a Vitamin D in the 50s is good for many people, but I definitely don't want to see it above 70. Taking a higher dose for a short period of time is completely acceptable, as long as it doesn't become something that you stay on for years. It is really hard, if not impossible, to get toxic levels of Vitamin D solely from the sun or diet. I only see it with people taking supplements. And usually it's not a low dose of supplements. (And actually, many people don't even realize that they are getting high doses of Vitamin D. It is added to a lot of vitamins and supplements - so that supplement you take for hair growth may contain a few thousand units of Vitamin D, for example. I ask everyone to get out all of their supplements and look through for vitamin D.) In general, getting vitamins and minerals from diet is preferable to getting from supplements.

Sorry about the rate limiting! That's a new-account issue, and I hate that it affects perfectly legit new accounts. I've switched that off now, so she can post freely. If you'd like, we can transfer your comments beginning "From devaboone" to her username. (Edit: done now, by permission via email. The parent comment was originally posted by conorh.)

(All: when you see issues like this affecting HN threads and feel like doing a good deed, please alert us at hn@ycombinator.com. We see all the emails but often have no idea what's going on in the threads.)

Some of comments show up on the thread but not necessarily on her comment history.

I'm not seeing that. Can you link to an example?

Actually I think I was mistaken. They were more recent comments posted on an older comment by someone else, so they show up further down in her history.

What is a “not low dose” of vitamin D? Would 5000iU a day still be low? 10,000iu?

Is it really possible to have enough vitamin d exposure just from diet for someone who lives in a northern state which doesn’t get nearly as many sunny days as a place like florida or california?

5000 IU is high dose. 10,000 is really high. A more moderate dose would be 1000 to 2000 daily. If you live in a northern state, your Vitamin D level will vary with season. And with increased use of sunscreen (which is a good thing), it can be hard to get enough Vitamin D. I'm not opposed to anyone taking Vitamin D (I take it actually). I just want people to take it in moderation unless there is a very clear reason for taking high doses (and there are indications for that).

My wife and I take 60000 IU twice a month. Not as a daily dosage. Would this still constitute as high dosage? We don't get a lot of sunlight here, and we don't step out that often these days.

What is the current scientific consensus on how to take Vitamin D? Daily doses? Single very large doses spaced every fortnight?

I've tried searching the internet before about Vitamin D and it's surprisingly confusing, both about dosage as about intake routine. Also confusing that daily requirements are contested to be way off to our real needs, it's just a lot of misinformation lingering around that I, as a layman, can't really parse it.

The supplements with 10000 IU are very common these days... now you scared me..

If taking Vitamin D do you recommend Magnesium and K2 as well, as I understand it these need to be in balance?

I don't know if K supplementation helps with calcium levels, but you don't need magnesium supplementation as long you have half-decent diet.

There is plenty of magnesium in foods.

It's true that there's magnesium in everything, but the definition of half decent diet becomes rather strange in the light of a recommended intake for adults.

Men are recommended a bit over 400 mg magnesium per day.

Black beans are quite rich in magnesium, but you still need to eat more than 3.5 cups of it to get the recommended daily amount of magnesium, or 5 cups of cooked brown rice, spinach? That's 2.5 cups of boiled spinach.

Generally, if you eat between 5-10 cups of solid food each day, you are fine no matter what you eat. But that's a lot of food unless you have a very physically active, job.

It used to be mostly true, when most people had physically demanding jobs, it's not true any more.


"National Health and Nutrition Examination Survey (NHANES) of 2013-2016 found that 48% of Americans of all ages ingest less magnesium from food and beverages than their respective EARs; "

Does this material affect your advice?


No, it doesn't. I haven't had a chance to really critically review the studies that are cited in that article, so I can't give an in-depth answer as to why that article is wrong. But I know that my recommendations are based on patients I have treated. And I have treated thousands of patients with parathyroid, calcium, and Vitamin D problems. That is all that I have done for the last 6 years, in fact. I've never had a patient require 8000 units of Vit D daily to get to a normal level - never. Yet this article would have me believe that 98% of people require over 8000 units to get Vit D in the normal range?! That is absurd. Anyone who has prescribed Vitamin D and watched levels knows that this isn't true. Many things published in medical literature are not valid, and not reproducible.

This study was based in Finland where they get very few hours of sun for a large part of the year.

I just spent a few minutes surfing her blog, and she actually has a really good answer to questions along the lines of "What do you think of study X?": https://www.devaboone.com/post/evidence-and-intuition-in-the...

No affiliation, not a doctor, etc., just thought this particular essay was well stated.

What about 60,000 IU/week for someone who had D,25-OH at 7. I did that for a few weeks. Now I am up to 44 and switched to monthly. It's a singel 5ml dose. You just drink it once instead of taking it every day.

Can you expand on what constitutes the "toxic" aspect of this, i.e., the danger, symptoms, consequences?

Thanks for coming here to share your expertise!

What are the ill effects of elevated blood-calcium levels? Is there a way to avoid the bad effects of high dose Vitamin D supplements? Thanks!

There's a range of symptoms, but with me it caused (or at least contributed to) a calcium oxalate kidney stone. Not fun.

Hi, I had a thyroidectomy and was told I lost at least one parathyroid in the process. Now my hands and feet are likely to fall asleep and I have low calcium levels (relative to lab standards). Would high vitamin D + calcium citrate be good for me? And should I see a specialist or am I okay just seeing a normal endo once a year?

Hi; is there anything documented about the following effect of taking high-ish doses of Vitamin D3 for a while: a tooth/jaw sensitivity appears, like you can "feel your teeth"? In the past I have used that as as signal to back off on the Vitamin D. What is the mechanism?

Do you recommend vitamin D2 or D3 supplementation?

i thought calcium was good for you. How is vitamin d causing high levels of calcium toxic?

Not a doctor, but I have had kidney stones.

The answer is a loss of calcium, so high level found in urine test: if you had way too much vitamin D, then you would start releasing the calcium from your bones.

I don't think that taking calcium supplements would help, because calcium metabolism (https://en.wikipedia.org/wiki/Calcium_metabolism) is much more complex than that.

Calcium metabolism is complicated, but there are a few things that are straightforward. 1. Vitamin D helps the intestines absorb calcium, so taking more Vitamin D can lead to more calcium being absorbed in your intestines, and thus more calcium in the blood. The excess calcium in your blood is caused by increased absorption from the intestines, not from bone release. (High calcium with parathyroid disease is caused by bone release, as well as increased intestinal absorption) 2. Taking calcium supplements along with Vitamin D will allow your intestines to absorb more of the calcium you are taking. 3. There are several reasons for having a lot of calcium in the urine. Primary hyperparathyroidism can do it, and in this case you will see high blood calcium levels also. If the blood calcium is low or normal (under 10.0 mg/dl), then you have another reason for high urine calcium.

Do you know what could be happening if taking vitamin D gives you severe headaches that last for days and gradually get weaker?

If you need more information, please ask away.

As someone who has worked on various deficiencies over the years, including vitamin D, I will suggest it means the dose you are taking is probably too high. When I had similar issues, reducing my sun exposure -- which was how I was improving my vitamin D status at the time -- resolved the headaches and vomiting that I was experiencing.

Thanks for the response. I'm surprised you can even get too much D with sun exposure. The thing is: I used to take vitamin D supplements fairly regularly, but now I barely take any. I will go weeks without supplementing, but when I do, I get headaches. No increased urination though, which would happen if i had excess calcium, and no nausea/vomiting.

Last time, i tried 5000IU, but this came after weeks of not taking any D supplement, and I've not taken any since. My reasoning is: that would effectively make the average dose < 400 IU, so shouldn't give me any problems, yet it does. Maybe I'm getting more from the sun than i realize :/

I'm surprised you can even get too much D with sun exposure.

I'm a special case. Trying to explain that is probably a can of worms.

shouldn't give me any problems, yet it does

There may be other factors there, which I could potentially speculate on. But A. It tends to be a can of worms when I start speculating like that and B. You didn't initially give enough info to really warrant such speculation. You only gave enough to make me feel like the safe bet was to comment on the dosage and leave it at that.

I understand. Thank you :)

I recently stopped taking my (self-prescribed) dose of 1,000 IU Vitamin D3. Before this I was on 2,000. I work all day and rarely leave the house, sometimes for a couple of weeks. I thought I was doing the sane thing.

A good number of months in and I start getting all of the symptoms - lethargy, constipation, stomach and intestinal pain, urinating very frequently and feeling like I had a kidney infection.

Bloods came back all normal, including vitamin D and calcium. My symptoms chime so much with Vitaminosis D (Vitamin D toxicity) that I wonder whether the serum levels are accurate indicators of such toxicity. Vitamin D is stored in fat and the calcium gets deposited in muscles - two possible mechanisms for this.

However, I do not know for sure. Either way I have been scared sh!tless of self-prescribing anything else. No matter how mundane it seems.

1000-2000IU is a low dose your blood work came back normal. All those symptoms are pretty generic as well, I'd look elsewhere.

It seems that you have to balance it with Vitamin K2


Thanks for the link and please have her include whether k2 supplementation is recommended or necessary along with the d3. I have been supplementing with k2 due to a history of kidney stones.

Could you elaborate in more detail? Given your wife's background, I'd guess you were referring to people with pre-existing hyperparathyroidism who are therefore prone to quickly develop hypercalcaemia from even modest Vitamin D supplementation, but perhaps there's more to it?

If your wife wants to write a blog post on the subject, I'm sure there'd be a lot of interest.

She was thinking about writing a blog post on Vitamin D already and she says she will it in the next few days and I'll post it here when she does. She is not talking about patients with pre-existing hyperparathyroidism - they often think they have it because the calcium is high, but it is only high because of the vitamin D!

You/she should put an email signup on her site or in a comment here. Would help people see the eventual article.

There are great questions on this thread, when she is available she will weigh in. I don't have the answers unfortunately! Feel free to reach out to her via her website too if you have very specific questions - she doesn't mind that at all.

Thank you. Somewhat related: I wanted to inform that ublock hides the submit button on the blog - if someone is having difficulty subscribing, they should trying disabling ublock for a bit before the submit button becomes visible.

Right now, I'd rather have a calcium problem than a Covid-19 problem. Also, some of the studies being thrown around in this discussion have mentioned that safe levels of Vitamin D are much higher than a lot of medical professionals actually think.

> there is virtually no risk of toxicity in supplementing up to 10,000 IU of vitamin D3 daily


I read the study that is cited on your link. It was a review article about Vitamin D, not a study on Vitamin D toxicity. And in fact, in the references for that article, there is no study cited directly related to Vitamin D toxicity that I can see. The cutoff at 10K is largely someone's opinion. I cannot say how many people will be harmed by taking such a high dose, but I know with certainty that toxicity at that dose is not rare, because I see it all the time. Some people can take very high doses and be just fine, calcium stays normal. Others will take 5000 units daily and end up with high calcium, and all the symptoms that go along with that (including kidney stones, fatigue, cardiac arrhythmias, etc). Now I am not saying that NO ONE should take high dose Vit D. Some people actually need that high dose, but that is only in the case of someone with very low Vit D and low calcium levels - often in someone who has problems with intestinal absorption, as you would see in someone who had a gastric bypass, for example.

Thanks for the response. I'm curious what your wife thinks about this article [0], mentioned elsewhere in this discussion. It makes the case that the current RDA for Vitamin D is based on a statistical error, and that the recommended dose should be closer to 8000 IU for young adults.

[0] https://pubmed.ncbi.nlm.nih.gov/28768407/

Not OP, but with vitamin D the dosage is actually something you can figure out empirically by testing vitamin D levels and taking supplements.

No one who talks about supplementation seems to think a level of 8000 over a long period is necessary to obtain adequate levels.

I think by the same token the recommended supplement level of 600 IU is inadequate to reach a sufficient level. But the paper in question didn’t test their result empirically.

Correct. It's fairly easy to know whether the dosage you are taking is working, since you can check levels. 8000 units is a really high dose, one that I have never had to give. The article suggests that 98% of people require that much to get to normal levels, which is almost laughable.

8000?? EFSA recommends a reference value of 1000 IU. And a tolerable upper intake level of 4000 IU.

FYI, that is the wife/doctor's account you replied to.

dang switched a lot of the comments to her personal username after the fact.

I'm also hesitant to take medical advice from a new account on an internet forum who is disputing medical research. Definitely not saying anything fishy is up, just that we should keep things in perspective.

What level of supplementation? I see huge ranges of vitamin D, by mouth or intramuscular, mentioned in this thread. As someone taking vitamin D (1k IU) with K2 I wonder what levels affect calcium.

All the vitamin D supplements I see in the pharmacy come combined with calcium. Should that take care of it or does "out of whack" mean calcium could be too high as well as too low?

Calcium supplements often include Vitamin D because it aids in intestinal absorption of calcium. That is actually one of the main roles of Vitamin D. You can find Vitamin D by itself, in anywhere from 400 to 5000 units per pill. Taking high doses of Vitamin D can cause high calcium (due to more being absorbed in the intestines), and taking extra calcium would just exacerbate that. If someone has low calcium levels, I recommend taking both calcium and Vitamin D. Low Vitamin D can cause low calcium levels.

Here (below) is a quote from the article, on the subject of calcium. (I suppose some of us may be reluctant or unable to have calcium levels monitored. But it seems all of us should be taking vitamin K2 along with our vitamin D.)

>The authors explicitly point out that each vitamin D supplementation must be accompanied by sufficient vitamin K2. This certainly prevents the rise of the calcium level in the blood, which is often seen as a risk for the supply of vitamin D

Vitamin K2 does help bones absorb calcium, but it will not prevent the blood calcium level from rising if you are really taking more Vitamin D than you need. This is simply wishful thinking.

A vitamin K deficiency with normal vitamin D levels would cause blood calcium levels to rise. Many people are deficient in vitamin K since it's mostly found in leafy greens and liver, no one's favourite foods. The difficulty is judging what is a normal vitamin D level by incidence of people with elevated calcium levels in the blood without having tested all of those people for vitamin K deficiency first.

Is there a way to determine if I'm deficient in Vitamin K2. If yes, is there a way to get supplements for it?

Is vitamin K safe to supplement? Or does it mess with the blood clotting?

People recommend really quite doses: K2-MK7 at 100 to 200mcg, or alternatively K2-MK4 15 to 45 mg (not mcg).

Fermented foods are a potent source of bioavailable K2

Is it true that Vit K2 ameliorates that problem? Or should that also not be taken blindly?

Without a reference to go by a quick Google indicates toxicity is only likely by taking far above recommended levels (max recommended is 4000iu daily) for an extended period.

Presumably people on those kind of doses are taking it under medical supervision, or are idiots/under the control of idiots.

I am not a doctor, but without further information it seems that as ever, following the guidance on legit supplies specifically and mainstream medical advice generally is a good rule of thumb.

There are some very vocal people who argue that the risk of toxicity is very low. The studies aren't great. But for most people, taking a moderate dose of Vitamin D will be safe. Unfortunately, I have treated many patients who come to me with high calcium levels due to taking Vitamin D. They do not have parathyroid disease (I have treated thousands of patients with parathyroid disease). They have simply been taking high doses of Vitamin D. High dose is generally 5000 units a day or more, though I have seen it occur with lower doses if taken over many years. Vitamin D is fat soluble, so it will stay in your system for a long time, building up. Of note, some of those patients were instructed by their doctors to take those high doses. Even doctors forget the relationship between calcium and Vitamin D, and I have spoken with doctors who did not realize that 5000 units a day could cause problems. As a doctor, there is a lot to know and remember, and most doctors haven't studied calcium metabolism in many years.

It makes sense many doctors, especially general practitioners, would forget or not know about the Vitamin D/Calcium link. However, wouldn't a doctor prescribing a large dose of Vitamin D take at least yearly standard set of blood tests too that would include calcium levels? Then again, that's assuming there's a fairly standard set of blood tests to check for imbalances of this kind. Also, it seems odd there isn't a standard procedure for prescribing Vit D that included "check calcium levels".

A large dose of vitamin D may not show up in the bloodwork for years if the patient keeps a fatty enough diet.

Would you mind telling us what the medical literature says about deaths from Vitamin D overdose? Around how many people in total have died from taking too much Vitamin D?

It is difficult to die of a Vitamin D overdose, though not impossible. Here is what happens: Vitamin D increases calcium absorption from the intestines. Over time, if you are taking too much Vitamin D, your levels can get very very high over time. Vitamin D is fat soluble, so you don't just "pee it out" like some water-soluble vitamins. It stays in you long-term. Eventually your calcium will rise. It can rise slowly, but you will get symptoms. Common symptoms would be fatigue, brain fog, insomnia, headaches, and kidney stones. If you are at levels where you could potentially die from Vitamin D overdose, your calcium levels will be high enough that you will feel acute symptoms of markedly elevated calcium: like vomiting and confusion. Someone will end up taking you to the hospital, because you will become unconscious. At that point you will be given IV fluids and the calcium will drop. You could die, especially if you have other health issues, but more likely it would be treated and you would get released. The effects of Vitamin D toxicity are related to the high calcium levels that it causes.

Do you test for vitamin K defficiency before taking the patients off vitamin D supplements?

Thanks for the reply and contextual information.

I've seen mention that the risk of overdose at 10,000iu daily is still very slow.

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