Vitamins are determined by their biological functions, not by chemical structure. Compounds which satisfy the functions of a particular vitamin are known as vit

Vitamins are determined by their biological functions, not by chemical structure. Compounds which satisfy the functions of a particular vitamin are known as vitamers of that vitamin. For example cyanocobalamin and methylcobalamin are both vitamers of B12 despite being chemically distinct. It's true that some vitamers are more easily metabolized by certain routes than others. In the example I gave, methylcobalamin is superior when it comes to oral supplements. Also if you can, try taking a multivitamin without minerals, and take a mineral supplement separately. A lot of minerals interfere with one another's absorption along with that of many vitamins (zinc, calcium, and iron should all be taken away from each other and from vitamin supplements).