I had a doctor tell me that 80-90% of pill vitamins pass out through urine, and that for the most part the industry was a scam.
Need extra iron, eat a rare steak every once in a while. Doc told me that’s why when they dropped my blood in that blue liquid it darn near cracked the bottom of the vial it sunk so fast.
My doctors (and I see MANY, and also include our pediatrician) have basically all said it is not necessary to take vitamins and so on unless something with your system might decrease what you need. In which case, a specific vitamin/mineral might be “prescribed”.
I take Vit D3 per a specified dose, by delicious chewables!
But really they say as long as you are on a reasonable diet, you should be getting the averages you need. My son takes multis because he is SOOOO damn picky and won’t eat much of anything.