B6 and Magnesium

Missing Accordion Menu for this widget.

Treatment Overview

Vitamin B6 (pyridoxine) is an essential vitamin that is necessary for more than 60 biological processes in a healthy human body. The body converts vitamin B6 into pyroxidal-5-phosphate (PLP), an enzyme that is used to release energy from starches and break down proteins. PLP is also used in the production of important chemicals in the brain.

Magnesium is an essential mineral that is necessary for the health of every cell in the body, including the proper functioning of brain and muscle cells. Magnesium deficiency is rare, but some research suggests that children with autism may have too little magnesium.

Some parents supplement a child’s diet with a combination of vitamin B6 and magnesium as an alternative therapy for autism.

Vitamin B6 and magnesium supplements can be purchased online, or from almost any grocery, drug, or health-food store.

Vitamin B6 is often included as one of many vitamins in a multivitamin supplement. It can be taken every day, but may be difficult to administer since some children may find that vitamin B6 tastes bitter when administered in tablet or powder form. Liquid B6 that seems to be better tasting for some children is also available. Doses of vitamin B6 in research studies averaged 18 mg/kg body weight/day (8 mg/pound daily), which is about 320 mg per day for a 40-pound child.

Magnesium is found in many foods, but is especially rich in green vegetables, seeds, nuts, and whole grains. It can be taken every day. While it is not clear what the proper dose for children with autism should be, one research report used a dose of 10-15 mg/kg/day (or about 180-270 mg total daily for a 40-pound child) divided into two doses.

If you choose vitamin B6 and magnesium as an alternative therapy, ask your child’s pediatrician about the dose appropriate for your child. Vitamin B6 can cause upset stomach when not taken with a meal, so also ask a physician to provide a sample schedule for taking B6 and magnesium.

The enzyme that is used to break down vitamin B6 into PLP may not work as well in children with autism. PLP is needed for the production of dopamine, a brain chemical that is very important for many behaviours. If children with autism are not producing enough PLP from the vitamin B6 they have in their diets, then supplementing with extra B6 may help boost the production of PLP to more normal levels.

Some researchers have reported that children with autism may have a magnesium deficiency. Children with autism can have significantly lower levels of magnesium in hair and blood than non-autistic children. There is evidence that magnesium supplementation can have a calming effect on some children with attention-deficit hyperactivity disorder (ADHD).

Aside from the necessity of magnesium for the overall physical health as well as the proper functioning of the brain, there is no specific theory about how magnesium deficiency could contribute to autism. The two supplements are often given together, as some researchers have reported that the side effects of vitamin B6 treatment are eliminated by magnesium. However, studies in which vitamin B6 was used alone did not report any adverse side effects.

There is some controversy surrounding the evidence for the effectiveness of vitamin B6 and magnesium in autism. Two small but well-controlled studies showed no effects, positive or negative, of combined vitamin B6 and magnesium therapy. One larger, but less well-controlled study showed positive and significant behavioural effects of combined vitamin B6 and magnesium, but not vitamin B6 or magnesium alone.

Two additional studies showed that vitamin B6 and magnesium had significant positive effects on behaviour in children with autism. There were, however, major problems with the designs of both these studies. In particular, the researchers in both of these studies knew that the children were receiving supplements. Therefore, their ratings of the children’s behaviour could be biased. One of these studies did include another small, double-blind, portion suggesting that vitamin B6 and magnesium treatment can improve behaviour in some children with autism.

The difference in outcomes of the various studies could be because vitamin B6 and magnesium results in positive behavioural effects for about half of those who try the therapy. Another explanation is that vitamin B6 and magnesium supplementation is not effective. The better-designed studies suggest that this may be the case, although these studies were so small it is difficult to draw conclusions from them.

Vitamin B6 can cause nerve problems at high doses (in adults, over 2g/day). However, studies of children with autism taking vitamin B6 and magnesium have reported no significant side effects. Furthermore, in children with epilepsy who had been taking high doses of vitamin B6 or PLP (900 mg for a 40 pound child) for six months, no significant side effects were reported.

Magnesium can be toxic at doses greater than 600 mg a day. However, studies using magnesium supplements at moderate doses (around 200 mg a day) have not reported significant side effects.

Check with your child’s pediatrician before starting treatment.


  • Holman, P. 1995. “Pyridoxine – Vitamin B-6.” Journal of Australian College of Nutritional & Environmental Medicine 14(1):5-16.
  • Strambi, M., et al. 2006. “Magnesium profile in autism.” Biol.Trace Elem Res 109(2):97-104.
  • Adams, J.B., and C. Holloway. 2004. “Pilot study of a moderate dose multivitamin/mineral supplement for children with autistic spectrum disorder.” J Altern.Complement Med. 10(6):1033-1039.
  • Rimland, B., and S.M. Baker. 1996. “Brief report: alternative approaches to the development of effective treatments for autism.” J Autism Dev Disord. 26(2):237-241.
  • Hunsinger, D.M., et al. 2000. “Is there a basis for novel pharmacotherapy of autism?” Life Sci 67(14):1667-1682.
  • Martineau, J., et al. 1985. “Vitamin B6, magnesium, and combined B6-Mg: therapeutic effects in childhood autism.” Biol.Psychiatry 20(5):467-478.
  • Adams, J.B., et al. 2006. “Abnormally high plasma levels of vitamin B6 in children with autism not taking supplements compared to controls not taking supplements.” J Altern.Complement Med. 12(1):59-63.
  • Fido, A., et al. 2002. “Biological Correlates of Childhood Autism: Trace Elements .” Trace Elem Electrolytes 19:205-208.
  • Starobrat-Hermelin, B., and T. Kozielec. 1997. “The effects of magnesium physiological supplementation on hyperactivity in children with attention deficit hyperactivity disorder (ADHD). Positive response to magnesium oral loading test.” Magnes.Res 10(2):149-156.
  • Nye, C., and A. Brice. 2005. “Combined vitamin B6-magnesium treatment in autism spectrum disorder.” Cochrane.Database.Syst.Rev. (4):CD003497.
  • Wang, H.S., et al. 2005. “Pyridoxal phosphate is better than pyridoxine for controlling idiopathic intractable epilepsy.” Arch.Dis.Child 90(5):512-515.
  • Tolbert, L., et al. 1993. “Brief report: lack of response in an autistic population to a low dose clinical trial of pyridoxine plus magnesium.” J Autism Dev Disord. 23(1):193-199.
  • Findling, R.L., et al. 1997. “High-dose pyridoxine and magnesium administration in children with autistic disorder: an absence of salutary effects in a double-blind, placebo-controlled study.” J Autism Dev Disord. 27(4):467-478.
  • Rimland, B., et al. 1978. “The effect of high doses of vitamin B6 on autistic children: a double-blind crossover study.” Am J Psychiatry 135(4):472-475.
  • Lelord, G., et al. 1981. “Effects of pyridoxine and magnesium on autistic symptoms–initial observations.” J Autism Dev Disord. 11(2):219-230.
  • Pfeiffer, S.I., et al. 1995. “Efficacy of vitamin B6 and magnesium in the treatment of autism: a methodology review and summary of outcomes.” J Autism Dev Disord. 25(5):481-493.
  • Schaumburg, H., et al. 1983. “Sensory neuropathy from pyridoxine abuse. A new megavitamin syndrome.” N.Engl.J Med. 309(8):445-448.

By Lara Pullen, PhD. The information from this page was reprinted with permission from Healing Thresholds. “Copyright (c) 2007, Healing Thresholds, Inc. All rights reserved”


Autism Canada does not endorse treatments, interventions and therapies but lists them so people can make informed choice.  This site is for information purposes only and is a starting point for readers to look into options that may fit or resonate.  Remember, therapies for autism, like any condition, should be discussed with a trusted medical practitioner or certified therapist before use.

All information, data and material contained, presented or provided here is for general information purposes only and is not to be construed as reflecting the knowledge or opinions of Autism Canada, or as providing legal or medical advice. All treatment decisions should be made by the individual in consultation with a licensed health care provider.

Back to Top