Between 10mcg to 15mcg, more than 15mcg makes me very jittery the same day and dizzy the next one.
I've been thinking about it lately because I sometimes had the exact opposite reactions with doses higher than 1000mg. I'd like Hans opinion on that too.
I have a Dr Clarke B1 supplement I found. It is expensive, but pure gelatine capsules with no fillers. I just took the lid off to check and it smells fine, even quite nice, in a plain sort of way. Just something to consider if you're not sure about the quality of the existing supplement.