For a long time now, we have been getting B vitamins in certain quantities - 50 mg, 100 mg, 250 mg etc. However, what's wrong with this type of B vitamin is that it's not natural. Nature doesn't create nutrients in "equal" amounts. It's all in nature's balance.
The body needs all nutrients in natural form and natural balance. Most of the B vitamins are water soluble and some are oil soluble
All the B vitamins handle different things. Here's some of the things the different ones handle. This doesn't cover them all but gives you some idea of what they do.
B1 Thiamine:
B2 Riboflavin
B3 Niacin
B5 Pantothenic Acid
B7 Biotin
B9 Folate
B12 Cobalamin