A multivitamin is not bad, but different vitamins need different other substances to be available for the body. Eg. some are soluble in water (like the B group) some, like vitamin D need fat to be solved in (and it's good to acompany it with vitamin K to make D work as intended). Be careful with vitamin A - people in developed countries usually have too much and it can cause serious problems. It's generally good to know what you're taking and why. But if you just need a quick fix, a multivitamin is usually ok.

If you eat a truly balanced diet you’ll have little reason to take a multivitamin. However, many people do not eat well. In those cases a multivitamin can help fill in the gaps. Arguably it would be better to improve your diet but something is better than nothing.

For me, they do seem to have an effect. I sleep better, my nails become strong and generally I feel more enegized. The latter is of course very subjective.

They can help when your body is under stress,illness, dieting, moderate exercise. otherwise the don't do much.

Our Pharmacology prof at med school always told us, as long as you live in the western hemisphere and don’t just eat pizza you only produce expensive urine with those vitamins. Ymmv though

Recommend these two things

https://www.theatlantic.com/health/archive/2013/07/the-vitamin-myth-why-we-think-we-need-supplements/277947/

https://www.pbs.org/wgbh/frontline/documentary/supplements-and-safety/

It's easy to find out if you take blood tests. You shouldn't be taking vitamins just for fun.

One thing a doc told me is that your body can only absorb so much. Some people go so crazy on certain supplements that they end up blocking the body’s ability to absorb other essential nutrients.

If you want to supplement, a single multi each day isn’t going to be a massive game changer, unless you’re already missing something.

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.