b complex jittery?

im taking a b complex but when i take it i feel more tired/jittery...i just started taking it for adrenals.........should i just decrease the dose or stop taking it? i know b vitamins are very important so what do i do...i have bad adrenal fatigue and i really need something? this is the one im taking........

http://www.nationalnutrition.ca/detail.aspx?ID=275




im not sure if theyre natural or synthetic but i think most are synthetic...but i need them so cant do much about that.....but y is it when i take them i feel more tired....it should be helping me with my adrenals........do i just need to give it a couple of days/?

also when there is a b complex in a complete multi vitamin it does not bother me.....just in a seperate b complex itself i feel jittery