It's unbelievable crazy what the author suggests, even say "10,000 IU if you're feeling daring / have darker skin / live in less sunny climates.".

Just a simple look at the side effects of high dosages:

Safety and side effects

Taken in typical doses, vitamin D is thought to be mainly safe.

But taking too much vitamin D in the form of supplements can be harmful and even deadly. Taking more than 4,000 IU a day of vitamin D might cause:

    Upset stomach and vomiting.
    Weight loss and not wanting to eat.
    Muscle weakness.
    Not being able to think clearly or quickly.
    Heart rhythm issues.
    Kidney stones and kidney damage.

Hi, author of the blog post here! Thanks for your concern. I do still stand by my claim, since more recent peer-reviewed studies have shown that up-to-10,000 IU is safe. As written in the post:

> McCullough et al 2019 gave over thousands of patients 5,000 to 10,000 IU/day, for seven years, and there were zero cases of serious side effects. This is in line with Billington et al 2020, a 3-year-long double-blinded randomized controlled trial, where they found "the safety profile of vitamin D supplementation is similar for doses of 400, 4000, and 10,000 IU/day." (though "mild hypercalcemia" increased from 3% to 9%. IMHO, that's a small cost for reducing the risk of major depression & suicide.)

So why then does Mayoclinic, etc, all say 4000 IU is the limit? I think because policy is decades behind science (this happened with trans fats), and also policymakers are much more risk-averse. (this is why in California, thanks to Prop 65, up until ~2018, there used to be a warning in every coffeehouse that coffee causes cancer.)

But thanks to your comment, I will edit the intro to note what the official max safe dose is, and that more recent peer-reviewed research shows it's too low!

It depends on the person, as a sample size of one I was on 5,000IU and my levels were still on the low end (almost still deficient), and my calcium levels were still safely on the low side as well. Ultimately people should be getting their levels checked before and after to see exactly what the effect on them is

To my understanding Vitamin D is regularly underdosed. Several points:

1) There are lots of studies that correlate Vitamin D production with sunlight exposure. For example, https://pubmed.ncbi.nlm.nih.gov/20398766/ this one lands on 1/4 of a MED = 1000 IU. Of course now we have a MED definition problem, but we're roughly talking single digit numbers for a white person in midday sun in NYC to reach 1/4 of a MED.

2) If you also supplement with Magnesium, a lot of your side effects go away. Vitamin D3 depletes Magnesium absorption.

I've been taking 20,000iu of Vit D daily for years, split into 10k AM/PM

Regularly have my Vit D levels checked and they are always within the upper bounds of healthy reference range

FWIW just anecdotally I took 160,000 IU per day for a few months along with 800mcg to 2mg of K2 MK-7 and about double the suggested amount of magnesium citrate. I slowly titrated up to that amount over a few months. I am not suggesting anyone else do that as I had a specific purpose slow action TPA when combined with many protease so to speak but just my own experience I did not have any of those issues. I don't know how they came up with them so I figure they are just guessing like they did with the toxic level of selenium which has a funny back story. I am back down to 5000 IU a day. Years later still none of those issues. But that is just me.

I did have one issue related to magnesium however. If I did a very high dose of magnesium taurate and a couple of other chelated forms I would have trouble catching my breath after physical exertion similar to chronic high doses of iodine. Not the end of the world but it was unnerving.

Don't anyone else do what I do. I experiment on myself more than scientists experiment on mice minus the whole dissection bit. I am just continuing some experiments from the 1900's but as I understand it AI will be learning all of those soon. Fascinating stuff really.