I found some conflicting information about methyl B12. Some are having great results and some like Huggins tell us to avoid it. The below info is taken from this site:
http://whale.to/w/b12.html



Note: According to the Heavy Metal Bulletin, March 1999, some researchers [including Dr Hal Huggins] and the International Academy of Oral Medicine and Toxicology in the USA have previously recommended caution in the use of methyl cobalamin injections in the treatment of amalgam patients. They feared that vitamin B12 in that form could readily methylate mercury in the body, ie. transform it into its more harmful form of methylmercury - when methylated, mercury is much more easily absorbed to the blood and then transformed to mercury ions, which are an intensely toxic form of mercury.