[DocG]

Absolutely, not only respiratory but all the illnesses. It affects your immune system. But with cavaets:

- It won't make any effect for around month once you start taking it

- it only has effect if you have serious deficiency.

I used to be sick really easily for years, always tired. Finally got doctor to make blood tests and if normal level 100, min is 60, then my vitamin D levels were 12. Ofcourse my body immune system struggled. After started with suppliments got more energy, got less often sick. Felt like a normal person.

There is also other extreme, taking too many will have negative effect. I've experienced them myself.

I do live in a northern climate (imagine Finland) with long dark winters and only sun time is spend in the office.

[yellow_viper]

The negative effects only happens if incorrectly supplemented.

75% of the population is suboptimal in Magnesium, without Mg - our ability to absorb D diminishes, even with supplementation.

Vitamin D must be supplemented with Vitamin K2 MK7 to ensure the extra calcium generated is deposited in the bones and not in the soft tissues (hypercalcemia)

Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786912/

Magnesium Supplementation in Vitamin D Deficiency. https://www.ncbi.nlm.nih.gov/pubmed/28471760

Low magnesium levels make vitamin D ineffective https://www.sciencedaily.com/releases/2018/02/180226122548.h...

Vitamin K: Double Bonds beyond Coagulation Insights into Differences between Vitamin K1 and K2 in Health and Disease https://www.mdpi.com/1422-0067/20/4/896/htm

Vitamin K2: A Vitamin that Works like a Hormone, Impinging on Gene Expression https://www.intechopen.com/books/cell-signalling-thermodynam...

[blurbleblurble]

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)

[tudelo]

> 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.

[belltaco]

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.

[mattmanser]

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."

[belltaco]

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

[XzetaU8]

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

[feanaro]

Why magnesium? Any references?

[vthriller]

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

Does this advice apply to people that work night shifts?

[OJFord]

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)

[ashildr]

Specimen 1) - A thorough meta analysis on a sizable amount of data

Specimen 2) - The first comment on hackernews: Unfounded anecdata

What a disappointment.