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Comment by mellosouls | Hacker News Reader

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.

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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.

Thanks for the reply and contextual information.

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?

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

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