There are six main vitamin groups that the human body needs for proper functioning. These are A, B, C, D, E and K. Out of these, A, D, E and K are fat-soluble, and are stored by the body to some extent in its fat reserves.
B and C however are water soluble and are excreted away as urine, when taken in excess. So these have more possibilities of being in deficit than the others.
Vitamin B is a family of substances grouped under the letter B that cause a number of significant body processes to go at a better pace and in a more orderly manner.
Out of these, Vitamin B12, also called cobalamin, is a particularly crucial cofactor in DNA production and fatty and amino acid metabolism.