[Broken_Hippo]

" So when do you not get enough of it? When you don't eat much food, or not enough of certain kinds of foods."

The exception to this is Vitamin D... if you live in certain areas of the world. In general, the closer you live to the equator, the less you'll need this supplement during the winter. I wound up with a low level last winter - enough to go to the doctor for testing. My other nutrients were just fine: I'm mostly vegetarian and eat fish about once a week.

I have to take the supplements from September through May. The other months I have the choice to take them. If I do not take them, I'm supposed to be outside for at least 15 minutes daily with exposed skin. Minimally short sleeves. I still take the supplements because I wear long sleeves for a good amount of summer.

This is the only supplement I see generally recommended here (Norway) simply because the way the sunlight is in winter.

[Amygaz]

Vitamin D supplementation is also sketchy and hotly debated topic in. Everyone agrees that it is important, but the currently accepted lower limit and whether you need to supplement if you are below is disputed. That limit was set based on extrapolating observations that were not fully controlled. So that limit has limitations basically. If you are healthy you shouldn’t bother with vit D suppl. If you have health concerns please do, but from a reliable source/brand. Supplements are not regulated.

[village-idiot]

Depends also on your skin tone. Generally the paler you are the more effective you will be at generating vitamin D at higher latitudes, even if it does result in easier burning.

Those with darker skin in high latitudes typically need more vitamin D in their diet/supplements.

[scns]

https://en.wikipedia.org/wiki/Hypervitaminosis_D

[baccheion]

Vitamin D goes with magnesium, and at higher amounts, vitamin K(2 MK-4).

[Broken_Hippo]

Both are pretty easy to get, though. I personally eat a lot of broccoli and tend to eat red, fatty fish once a week. Unless the doctor says something, most folks won't need to take those supplements. It is a lot more difficult to meet your vitamin D needs through food, however.

[baccheion]

Magnesium deficiency/insufficiency is almost as common as vitamin D's. If status hasn't been verified by something like an RBC or WBC magnesium test, then it isn't really known.