I’ve been taking multivitamins whenever I break a fast. It also depends on what you consume on a regular basis, maybe you are already deficient of particular vitamins & minerals. For example I rarely eat fish so I also take omega 3/6 supplements.
I take a prenatal, which is basically a multivitamin. I too take it to fill in the gaps. especially if I have a day where I don’t eat as healthy as I should. Don’t notice much of a difference but I’ve been taking them for so long.