I have to take Vitamin D all year. I got really sick a year and a half ago due to low levels and wound up with some other issues that it triggered. Turns out, I have MS and the low vitamin D probably helped trigger a flare.

I literally cannot get enough Vitamin D in the winter: The days are short here in Norway and the sun isn't enough. Theoretically, I might be able to get it in the summer, but I really need to wear strong sunscreen since a medicine increases my skin cancer risk. The neurologist doesn't really want me to not take the supplements anyway.

My diet isn't bad. Mostly vegetarian, though I try to eat fish once a week and not otherwise completely devoid of animal products (dairy, for example). The rest of my bloodwork turns out OK.

In my case I am an endurance athlete, so at minimum supplementing electrolytes is helpful (also during the fast electrolyte supplements have at least seemed beneficial to my experience). Also, most American's are low on Vitamin D, and trust me I prefer it from the sun myself, but currently Im an office worker, so I supplement that.

Anecdotally, I can tell you that historically I used to get sick 2-3 times a year minimum, and since I began taking vitamins 5 years ago I got sick 1 time.

But I do generally agree with you about vitamins and minerals coming from diet over supplements, but I also say if you can get all your vitamins and minerals from food, your just not running enough (thats a joke).

That also assumes you're getting enough sunlight. A lot of people who work in an office don't.

That's a bad diet compounded by a bad lifestyle. Working in an office does not mean one has to stay indoor all the time and at weekends.

If you live far enough North it basically does mean that for a good part of the year. Going to the office, it's dark, and it's already dark again when leaving. Need that supplement.