Vitamin B6 is sometimes discussed as a Complementary and Alternative Therapy (CAM) for individuals with autism spectrum disorders (ASD). Lurie Center clinicians summarize current research on vitamin B6. We recommend that you also read about magnesium.
Vitamin B6 (also called pyridoxine) and magnesium are cofactors in more than 100 metabolic pathways. Cofactors help the action of enzymes (complex molecules that cause chemical reactions to take place in the body). Some of the metabolic pathways in which vitamin B6 is involved produce and break down neurotransmitters, or chemical messengers, in the nervous system, such as serotonin and dopamine.
Studies documented cortical (brain) excitability in rats deficient in vitamin B6 in the 1940’s and it was noted that some infants with seizures improved with vitamin B6 in the 1950’s. The use of megadose (very high dose) vitamin therapy began in the 1950’s with attempts to treat patients with schizophrenia. In 2002 a well-done study showed no effect from supplementing these patients with vitamin B6. Vitamin B6 was first proposed as a supplement in autism because of previous use in schizophrenia and seizures. This occurred simultaneously as the idea that autism is a biological, neurologically-based problem was first proposed (Rimland 1964 Infantile Autism: The Syndrome and Its Implications for a Neural Theory of Behavior).
Vitamin B6 is sometimes suggested by neurologists as a supplement in brain disorders such as epilepsy (seizures), Parkinson’s disease, and Alzheimer’s disease, and is given in a relatively low dose of 100 mg twice daily. Unfortunately, it is not known whether vitamin B6 makes any difference in those conditions because it has not been studied in controlled trials.
The Autism Research Institute’s (ARI) website noted in the past that 46% of children improve with vitamin B6 and magnesium. This is the result of parent reports only, not objective measures. It is difficult to track improvement or decline in children with autism because many have cycles of better, then worse, behavior, and many are also involved in more than one therapy that may change while the child is on supplements.
Megadoses of vitamin B6 (often considered higher than 200 mg per day) can lead to irritability, hypersensitivity to sound, urinary incontinence, nerve damage (neuropathy) and photosensitivity. In our experience, although parents may see a change (positive or negative) in the short term, few continue to give megadose vitamin B6 to their children because of the difficulty in teasing out whether or not it really makes a difference and because of the activation and irritability seen in long term treatment.
See related information on magnesium.
- Davenport VD, Davenport HW (1948) Brain excitability in pyridoxine-deficient rats. J Nutr 36:263-275.
- Molony CJ, Parmelee AH (1954) Convulsions in young infants as a result of pyridoxine (vitamin B6) deficiency. JAMA 154:405-406.
- Lerner V, Miodownik C, Kaptsan A, Cohen H, Loewenthal U, Kotler M. (2002) Vitamin B6 as add-on treatment in chronic schizophrenic and schizoaffective patients: a double-blind, placebo-controlled study. J Clin Psychiatry 63: 54-58.
- Scott K, Zeris S, Kothari MJ (2008) Elevated B6 levels and peripheral neuropathies. Electromyogr Clin Neurophysiol 48:219-223.
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- Olpe H-R, Steinmann MW, Brugger F, Pozza MF (1989) Excitatory amino acid receptors in rat locus coeruleus: a extracellular in vitro study. Naunyn-Schmiedeberg’s Arch Pharmacol 339: 312-314.