Yeah, apparently you would be wise to supplement because anytime you chelate the body is under some stress and uses up more vitamins/minerals (particularly antioxidants), but the good thing about ALA is it is already an antioxidant in itself and good for the liver. Problem is, it can increase copper in the body so it is best not to take supplements that contain copper. This is also one reason why you need to take breaks between chelation rounds.

I dont think you need anything to absorb mercury, ALA is a pretty powerful chelator. But you can if you feel it may help. this is why some people take DMSA, for extra "grip" I guess and also to perhaps grab any that may have been left floating around in the blood. But ALA is fine to use as a chelator by itself.

Supplements recommended (by andy) are vitamin C, B complex, milk thistle (these all must be taken 3-4 times a day for effectiveness or they get used up too quickly, you can split tablets up to do this), and zinc, vitamin E, magnesium, selenium (in the form of selenomethione), flaxseed oil for essential fatty acids (omega 3 etc) (I mix it in with my yoghurt, it is really nice like that). You can use about a tablespoon or 2 a day. I only take a full teaspoon of it in my yoghurt, but I have it about 3 times a day.