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Comment by blurbleblurble | Hacker News Reader

If you take a lot of vitamin D, you have to make sure that you are getting enough magnesium.

Also, vitamin D really shouldn't be taken any other time than before noon.

(Not sharing this for you in particular, just for anyone reading who decides to try vitamin D supplementation for the first time. Doctors aren't always sharing she vital info about how to take vitamin D)

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> Also, vitamin D really shouldn't be taken any other time than before noon.

I'm sure I could go find sources, but it might be helpful if you link them here. It's hard to believe comments that give medical information and disparage doctors.

I'm actually just completing a high-strength vitamin D tablet course and the advice for taking it in the instructions is to take it with your evening meal, so sounds like a load of hogwash.

Here, for example, are the instructions that came with my tablets:

https://www.sunvitd3.co.uk/site/wp-content/uploads/2019/01/S...

Note the:

"Please Note: SunVit-D3® tablets should be swallowed whole with water and taken in the evening with a main meal."

The reason for that recommendation is that Vitamin D absorbs better in a meal with fat, and dinner is the biggest meal for most people.

See my other comment in reply to parent. There might be lower quality sleep because of the timing.

https://www.gwern.net/zeo/Vitamin-D

The theory is that vitamin D intake helps set the circadian clock because it has been correlated with exposure to sunlight for hundreds of millenia. I think Gwern did a single blind experiment on himself and found some correlation to lower sleep quality if it's taken at night.

https://www.gwern.net/zeo/Vitamin-D

Why magnesium? Any references?

> vitamin D really shouldn't be taken any other time than before noon

Does this advice apply to people that work night shifts?

I believe the actual science (rather than than that it's somehow sensitive to the time of day) is that it requires sunlight (UV) exposure to absorb, rather than just be excreted.

So if you work a nightshift, hopefully there's some opportunity still to get some sunlight either side, and you should take it before that.

(IANA healthcare professional)

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