Vitamins are barely regulated and don’t have to pass the standard of “generally recognized as safe and effective”. Because of that we don’t even have a ton of data on the effectiveness of multivitamins, but one of the things that we do know is most of the vitamins are just pissed out because they need cofactors to be properly absorbed. If you truly can’t get nutrients from a healthy diet then they are better than nothing but healthy diet is still the number one priority.

Doctors sometimes recommend them because “they can’t hurt” but that doesn’t mean they are actually helpful