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After my last post about reactive oxygen species and oxygen-induced seizures, I decided that I should check my files rather than rely on my memory, and discovered, as always, you should check your files and not rely on your memory. I found a couple of references about vitamin E that I had forgotten about. Jerrett et al. also studied the protective role of vitamin E in oxygen induced seizures in mice (1) . They reported that in normal mice exposed to 3 ATA of oxygen, 50% seized within 60 minutes. In mice that were fed a vitamin E deficient diet for 3 months, 100% seized within 60 minutes (although they did no measurements to show that the mice were truly deficient in vitamin E). In a third group, mice fed a normal diet were given a single injection of vitamin E before the oxygen exposure, and none of these mice seized. In a study unrelated to hyperbaric oxygen, Levy et al. reported that vitamin E was not protective against other types of seizures (electrical, kanic acid) in rats (2) . The issue of vitamin C is interesting. If anyone knows of specific references about vitamin C, please send them to me. Vitamin C, as you may know, is a water soluble vitamin. Water soluble compounds do not have free access to the brain, as the blood brain barrier prevents free entry from the blood into the brain. As with most water soluble compounds, there has to be a specific transport mechanism for the compound to get into the brain. Water soluble vitamins have an elaborate mechanism by which they enter the brain. In the choroid plexus,(the site of cerebrospinal fluid formation), there is a highly specific transporter which conveys vitamin C from the blood to the cerebrospinal fluid. Once in the cerebrospinal fluid, vitamin C is then transported into the brain (3) . The brain levels of vitamin C are normally much higher than blood levels (3, 4) . The transport mechanism for vitamin C is saturable, meaning that it will transport only so much vitamin C into the cerebrospinal fluid irregardless of how high blood levels are. In rabbits, administration of 423 mg/kg of ascorbic acid increased blood levels by about 200 fold (0.7 to 140 mg/dl); however brain levels only increased from 27 to 31 mg/dl (4) . Similar transport mechanisms appear to function in humans (3) . So I'm not so sure that by taking large amounts of vitamin C, you can increase your brain levels. Again, all of this information is provided solely for your information, and is not an endorsement of any form of treatment. Eddie Brian eddie-brain@ui*.ed* 1. Jerrett, S. A., D. Jefferson and C. E. Mengel. Seizures, H2O2 formation and lipid peroixdes in brain during exposure to oxygen under high perssure. Aerospace Medicine 44: 40-44, 1973. 2. Levy, S. L., W. M. Burnham, A. Bishai and P. A. Hwang. The anticonvulsant effects of vitamin E: a further evaluation. Can. J. Neruol. Sci. 19: 201-203, 1992. 3. Spector, R. Vitamin homeostasis in the central nervous system. New England Journal of Medicine 296: 1393-1398, 1977. 4. Spector, R., A. Z. Spector and S. R. Snodgrass. Model for transport in the central nervous system. Am. J. Physiol. 232: R73-R79, 1977.
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