Vitamin B6 (also known as pyridoxine) is a water-soluble vitamin found in many foodstuffs including meat, fish, eggs, potatoes, beans, nuts and cereals.
It has several important functions, including allowing the body to use and store energy from protein and carbohydrates in food. It also helps to form haemoglobin, the substance that carries oxygen around the body.
Magnesium is a mineral found in many foods, such as leafy vegetables, grains and nuts, as well as meats and dairy products. It activates enzymes, contributes to energy production, and helps regulate calcium levels, as well as copper, zinc, potassium, vitamin D, and other important nutrients in the body.
Some people have suggested that some individuals on the autism spectrum do not have enough vitamin B6 and that this can lead to a wide range of difficulties (such as difficulties with social communication and social interaction).
Some people believe that that those difficulties can be overcome by eating more foodstuffs that contain vitamin B6 or by taking vitamin B6 supplements. Magnesium supplements are sometimes taken at the same time as the vitamin B6 supplements to counteract the side effects of the vitamin B6.
It is unclear whether most individuals on the autism spectrum do or do not have a deficiency of vitamin B6. It is also unknown whether a vitamin B6 deficiency can cause or worsen symptoms (of autism or related issues) or arises because of autism, or is completely unrelated to autism.
There is a reasonable amount of low-quality research (11 group studies and two single-case design studies with three or more participants) into the use of vitamin B6 and magnesium supplements as an intervention for individuals on the autism spectrum.
However, because the quality of that research is so poor, we cannot determine whether vitamin B6 and magnesium is likely to provide any benefits to anyone on the autism spectrum. We must wait for further research of sufficiently high quality to be completed.
There is a need for further research into the use of vitamin B6 and magnesium supplements for people on the autism spectrum. Specifically, there is a need for studies which use robust methodology, for example, large-scale, placebo-controlled, randomised, double-blind trials carried out on several sites.
That research should also identify which individuals are most likely to benefit from which formulations and dosages; should determine if vitamin B6 and magnesium supplements can be used as one of the elements within comprehensive, multi-component, treatment models; should compare vitamin B6 and magnesium supplements with other interventions which are designed to achieve similar results, such as special diets.
That research should also identify if vitamin B6 and magnesium supplements have any beneficial or harmful effects in the medium to long term. It should also involve people on the autism spectrum in the design, development and evaluation of those studies.
There is some evidence that taking excessive amounts of vitamin B6 and magnesium supplements can result in potentially harmful effects, such as nerve damage to the arms and legs, hands and feet.
Because of this, we cannot recommend the use of these supplements. If you are taking any kind of dietary supplements you should follow guidance on their usage from the appropriate organisation in your own country (such as the Food Standards Agency in the UK or the Office of Dietary Supplements in the USA).
Please read our Disclaimer on Autism Interventions