QBC (quercitin/bromelain/vitamin c) seems to have a very good effect on my attention span, ability to concentrate, anxiety levels, etc. However it does not go well with coffee, I get a "speedy" feeling I don't like. So unfortunately I don't take this supplement as much as I would like, because I love coffee so much.

Other nutritional remedies can be found in "Prescription for Nutritional Healing" by Balch.