I hope you plan to fast on fresh juices, which are VERY supportive nutritionally and very healing. I presume you know about cilantro for chelating those heavy metals! DEFINITELY add a bunch to your daily juices!
If you can, get hold of the excellent book on juice fasting by Paavo Airola, How to Keep Slim, Healthy & Young with Juice Fasting. It has all the info you need for a successful fast.