There is extremely solid evidence that 4000 IU or 100 mg a day is completely safe for all adults. There are some recent large studies that back this up.

I think you mean 100 mcg.

I suggest blood work over guess work. Dieticians are recommending quite a bit more than that.

Definitely not 100 milligrams

Don't listen to this. Just talk to your doctor and supplement. The main way that humans get vitamin D is sunlight. If you aren't outdoors a lot or live far north it's even more likely you need it. It would be good to get tested by your doctor, maybe with your current lifestyle you are just fine and your vitamin D levels are normal. Mine weren't, taking supplements got it back up to normal.

That's provably incorrect. Any phrase that refers to "supplements" as one thing can be safely dismissed

Why would it destroy the liver? One wouldn’t take it like cookies, would they?

Also there are disintegrating strips/films. There’s one for Mecobalamin at least, that I was prescribed.

what foods would you recommend for vit d?

Direct sun exposure.

Just stand facing the sun and open your mouth.

If you live in the north, the sunlight you might get is inadequate.

Also it’s hard to expose skin to sun zero temperature.

I’m guessing northern ancestors ate organ meat for supplements in the past.

I read an interesting theory that people near rivers ate fish and were able to be healthier than the people inland. And also tended to retain the darker complextion of their southern ancestors.

I read that years ago it's in my brain but no idea where it comes from.

That's not possible during the winter in countries in northern climates.

But preferred when it is possible.

Fish

anything you want that is source of vitamin D3

https://www.healthline.com/nutrition/vitamin-d2-vs-d3#TOC_TI...

Below are "a few ideas" listed from the article (direct quote):

1- mushrooms that have been exposed to ultraviolet light (11Trusted Source)

2- Take fish oil supplements such as cod liver oil

3- Eat fatty fish twice a week (12Trusted Source)

4- Choose milk or orange juice that’s been fortified with vitamin D

5- Eat some eggs and butter (13Trusted Source)

6- Spend at least half an hour in the sun daily, if possible

My thoughts on their recco:

Option 6 is the typical US doctor prescription before vitamin supplements and seems the most reasonable, though depends on your location.

Options 3 and 5 are legit options and worth noting. Not sure if the portion sizes would be a financial detriment to many though.

Option 2 and 4 essentially seem like taking Vitamin D supplements.

Option 1 is huh? Who has a UV gun for mushrooms? Do stores do this automatically?

You simply let your mushrooms get 30 minutes of sun exposure daily.

"choose milk or orange juice that has been fortified with vitamin D" You mean like supplements?

Yeah, I've seen "Vitamin D enriched" mushrooms at the Coop supermarket in the UK.