I'm pretty sure multivitamins help me in one way - to help prevent me from catching colds and flus easily. I noticed this years ago when my kids were young. I would take one of the chewable kids vitamins daily through autumn and winter. Several winters I did not get sick. I've not done it since - every day, one kids vitamin. I switched to adult multis but I think they're an expensive overload and didn't seem to help. But chewable kids were too sugary for my teeth. Now they have the xylitol ones. I may try again this season.

Depends on how significant the deficiency is. If it's pretty bad, you would probably be better off taking supplements of just that thing along with the daily multi. Or even changing your diet if it's really extreme or caused by how you eat (like a vitamin d deficiency from not eating greens, going outside or drinking milk).

I take it when i have some symptoms of vitamin deficiency like if you're sitting in one place and get up and you feel some weird sensation in the legs or hands. Like hundreds of ants running inside the veins. Or when I forget to drink water and get dehydrated and the body loses vitamins. I usually don't take such meds.

Currently I’m in the process of figuring out if I actually need extra vitamins. I’m using a food tracking app that also includes vitamins and minerals, not just fats and carbs like most apps do. It’s a lot of work, but I’m not planning to do this forever.

So far, I’ve found out that vitamin A and D might come in handy, but everything else seems fine.

My neurologist has me take L-methylfolate because of one of my meds. Besides that, all I take is fish oil and D3. Everything I've seen has said they're some of the only ones that actually do anything.

The water soluble ones like Vitamin C you just piss out. The fat soluble ones like A can build up and cause problems. NTM my grocery store generic oil and D together cost way less that the multivitamins.

Is "moving money" = "doing a thing"? :-)

They taste good, sometimes.

Multivitamins are pretty much like the train to Hogwarts. They only work if you believe they work!

I look at them the way Voltaire looked at going to church. To paraphrase (going from memory here), "If heaven exists then by going to church every Sunday I've saved my soul, if it doesn't then I've only lost a few hours every Sunday." Multivitamins are cheap enough that I can take them on a "just in case" condition.

Do you live in the God Forsaken northern lands? If so, vitamins can be beneficial during your Hellish Winters that humans are not supposed to inhabit. Migrate to sunnier climes.