Adverse effects of high vitamin B(6) intake include peripheral neuropathy. Recent studies focussing on the reduction of plasma homocysteine as a risk factor for vascular disease showed that vitamin B(6) reduces plasma folate levels.
- Ann Nutr Metab 2001;45(6):255-8 -- Plasma folate but not vitamin B(12) or homocysteine concentrations are reduced after short-term vitamin B(6) supplementation. -- Bosy-Westphal A, Holzapfel A, Czech N, Muller MJ.
Excess dietary pyridoxine affected brain and serum concentrations of some amino acids and binding properties of cortical serotonin receptors.
- J Nutr 1998 Oct;128(10):1829-35 -- Dietary excess of vitamin B-6 affects the concentrations of amino acids in the caudate nucleus and serum and the binding properties of serotonin receptors in the brain cortex of rats. -- Schaeffer MC, Gretz D, Gietzen DW, Rogers QR.
Vitamin B6 can interfere with medications for parkinsonism.
- Nebr Med J 1972 Sep;57(9):366-76 -- Comments on the adverse effect of concurrent pyridoxine administration on the efficacy of L-dopa in treating parkinsonism. -- Pfeiffer RF.
Anti-epileptic drugs may decrease vitamin B6 levels.
- Europ J Paediatr Neurol 2000;4(6):269-77 -- Anti-epileptic drug treatment in children: hyperhomocysteinaemia, B-vitamins and the 677C T mutation of the methylenetetrahydrofolate reductase gene. -- Vilaseca MA, Monros E, Artuch R, Colome C, Farre C, Valls C, Cardo E, Pineda M.
Neuropathy associated with pyridoxine abuse.
- Neurology 1985 Oct;35(10):1466-8 -- Sensory neuropathy with low-dose pyridoxine. -- Parry GJ, Bredesen DE.
An eruption resembling acne rosacea that was temporally associated with daily ingestion of high-dose B vitamin supplement. The eruption failed to respond to the usual treatment regimens for rosacea, but promptly improved when use of the vitamin supplement was discontinued.
- Cutis 1991 Aug;48(2):119-20 -- Acneiform eruption due to "megadose" vitamins B6 and B12. -- Sherertz EF.
Treatment with pyridoxine or a B-vitamin mixture led to an increase in serotonin content of various brain areas and to a decrease in the number of serotonin S2 receptors.
- Klin Wochenschr 1990 Jan 19;68(2):142-5 -- Influence of B vitamins on binding properties of serotonin receptors in the CNS of rats. -- Dakshinamurti K, Sharma SK, Bonke D.