Very cute @PirateGirl If you need to add niacin you can also use a vitamin B complex/complete. You just have to look at the label and see how much niacin it has. I found a B100 complete that was a powder in gel pill. I ended up picking mine up at Safeway in the vitamin section. I just add it to the food. I have only ever found brewers yeast at the natural grocery type stores.