Multivitamins are very nutrient dense and cheap.
Considering multivitamins cost basically nothing, you don't have to care about paying for the stuff you end up peeing out.
1. Take it together with food (containing fat) so it gets dissolved. 2. For each micronutrient check if it's in the best available form, and big enough dose.
I always tell people treat vitamin deficiency with a healthy diet, if that doesn't work you have a gut problem and pills won't fix it either. I'm not a doctor, but it is a reasonable claim.