M.H.
Niacin is actually what closed down many mental hospitals in the south at the turn of the 20th century. When doctors experimented with the supplement many people were released and sent home because nothing was wrong with them. The lack of this particular nutrient can cause many things that are diagnosed as mental issues these days. Stress also depletes nutrients....so you can get into a big cycle if you're worried about the depression.
It is very easy to be replete in Niacin with our food supply now. It's worth a try. You can get too much but you will notice with flushing and nausea. It's not dangerous but you should be aware if you need to back off. The 100mg you're getting in your B-stress vitamin should be plenty if you're absorbing everything. Absorption is critical
God bless!
M.