ABSTRACT
Megavitamin therapy generally involves the use of the water-soluble vitamins, either singly or in combination, for the treatment of various disorders of the central nervous system or other organ systems. In order for megavitamin therapy to work directly on the brain, one might expect that megavitamin therapy would alter the vitamin concentrations in cerebrospinal fluid and brain. Before water-soluble molecules in the blood can enter the brain, the molecule must enter the extracellular space of brain or the cerebrospinal fluid which bathes the brain's surfaces. Passive mechanisms, however, cannot explain the distribution of the various vitamins in the central nervous system. Thus, as in the case of thiamin deficiency, when severe, the homeostatic systems for vitamin B6 in the central nervous system can ultimately fail with the evolution of a pyridoxine-deficiency encephalopathy. Megavitamin doses of riboflavin and vitamin B12 have been used for the therapy of several brain disorders.
