Just to clarify for you: the difference between the B50 and the B100 is that most (not all) of the vitamins will have either 50 mg (mcg) or 100mg (mcg), respectively.
If you do a little rearch online for RDA's on the B's you should put your mind to rest. I have a great website but you cannot post links on these forums. For Your Information:
RDA for B1
(thiamin) is 1.5mg - it can be tolerated at levels 2 to 3 times higher than this.
RDA for B2
(Riboflavin) is 1.7mg - it can be tolerated at levels several times this (this is the B vit that turns urine very yellow
RDA for B3
(Niacin) is 20mg, but it can be tolerated at much higher levels and is often used to help lower cholesterol in very large doses - it can cause flushing of the skin, however. This typically doesnt happen until you reach 100mg.
RDA for B5
(PantothenicAcid) has not been established; however the adequate intake (AI) is set at 5 mg for adult males and females. Doses larger than 10g can cause diarrhea.
RDA for B6
(Pyridoxine) is 2mg, doses higher than 500mg can cause adverse reactions
RDA for B12
(Cobalamin) is 6mcg - there are no noted adverse reactions with very high doses of this vitamin. B12 injections typically contain 3000mcg, FYI.
If you're looking for a little more energy try adding ginseng to your regime. There are a few types (siberian, panax, C.A. Meyer) but they are all adaptogens that helps with moods, energy, libido, immune function and cognitive function.
BTW, have you had a complete physical lately? There are many conditions that could leave you feeling drained, tired and out of energy.