He wouldn't stop all medication. If he's taking supplements he is obviously medicating himself in some way.

If the lithium is helping then talk to your doctor about the natural supplement and see if they wil help you with the dosing. Then you could see a GP/Doc every 6-1 year and get blood work done. Lithium is pretty cheap though so your doc may give you a really long supply and you could just visit every 6 months. Talk to your doctor about your options and if he/she will support you.