Vitamin B6, Magnesium and Autism Ranking: Insufficient/Mixed evidence

Vitamin B6 capsules

Vitamin B6 (also known as pyridoxine) is a water-soluble vitamin found in foodstuffs such as 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.

Some people think that individuals on the autism spectrum have significant metabolic abnormalities which can cause or worsen the symptoms of autism.

They also think that some of those metabolic abnormalities can be addressed by consuming more foodstuffs containing vitamin B6 or by taking supplements of vitamin B6.

Excessive vitamin B6 can result in nerve damage to the arms and legs so magnesium supplements are sometimes taken at the same time as the vitamin B6 to counteract possible side effects.  However high doses of magnesium from dietary supplements can cause diarrhoea accompanied by nausea and abdominal cramping.

Our Opinion

There is some limited, poor quality research evidence to suggest that taking supplements of vitamin B6 and magnesium may produce some benefits in some people on the autism spectrum. However the results of the research studies are inconclusive and sample sizes were small. Therefore the use of vitamin B6 for improving the behaviour of individuals with autism cannot currently be supported.

We recommend that future research should explore the long term effectiveness of vitamin B6 treatment while addressing the methodological shortcomings of the existing studies. 


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31 Oct 2017
Last Review
01 Oct 2014
Next Review
01 Oct 2017