In the south of Europe, however, methylcobalamin is generally used to treat disorders such as neuritis and polyneuropathia. Highly recommended by the Swedish Association of Dental Mercury Patients, it is usually the drug of choice for the treatment of patients with amalgam-induced disorders. In the experience of Dr. Ahlrot-Westerlund among others, B12 in its active form, methylcobalamin, gives a much better result than other forms which have to be transformed into methylcobalamin. It is possible that the process of transformation itself is inefficient in many patients. It has been suspected that the supplementation of methylcobalamin in the presence of mercury could lead to the formation of methyl mercury.
Inorganic mercury steals methyl groups from methylcobalamin, and methyl mercury is formed.
However, methyl mercury is not more toxic than inorganic in mercury and the positive effects of B12 supplementation in this form seem to outweigh the possible disadvantages. Preservatives Methylcobalamin should be obtained with dry substance and liquid packed separately to increase the shelf life. The preparation should be kept in the dark stored at a temperature below 25 degees C and used within a year. Many of the vitamin B12 preparations on the market contain preservatives which can cause problems in sensitive patients. The corresponding Japanese preparation, Esai's Mecobal, contains only 0.5 mg B12.