We have identified 13 articles published in English-language, peer-reviewed journals which evaluate the efficacy of vitamin B6 and magnesium as an intervention for children and young people on the autism spectrum. Only one of these studies (Kuriyama et al, 2002) evaluated vitamin B6 by itself (without magnesium).
The article by Lelord et al from 1982 appears to describe the same study as the article by Lelord et al from 1981. It is not always clear if any of the other articles by the same research group (which included Barthélémy and Martineau) described unique studies or were articles which described the same studies.
The studies we identified included more than 300 individuals on the autism spectrum aged from one year old to 18 years old, although the bulk of studies were of children and young people. Individuals with specific diagnoses included people with autistic disorder, Asperger syndrome or pervasive developmental disorder - not otherwise specified.
The length of intervention varied between two weeks and 40 months, although in most cases the intervention lasted for between two and 10 weeks. It is difficult to identify the dosages used because different researchers used different ways of calculating the dosages. For example, Lelord et al (1981) stated that the dosages varied between 400-1125 mg of vitamin B6 and 400-500 mg of magnesium, whereas Tolbert et al (1993) stated that the dosages were 200 mg of vitamin B6 per 70 kg body weight of each participant and 100 mg of magnesium per 70 kg of body weight of each participant.
Please note: These dosages were well above the recommendations made by The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment in 2003. The Committee suggested the following dosages: 1.4 mg per day and 1.2 mg per day for males and females respectively.
11 of the studies used a group design, usually comparing a group of people receiving vitamin B6 and/or magnesium to a different group receiving something else. In some of those cases, the other group received a placebo, and, in some cases, the other group received only vitamin B6 or only magnesium. Two of the studies used single case designs, where the participants received vitamin B6 and magnesium but nothing else.
*Please note: We have not included articles with less than three participants on the autism spectrum, articles which did not examine the efficacy of vitamin B6 and magnesium as an intervention for people on the autism spectrum or articles which examined the efficacy of supplements containing a range of vitamins and minerals.
Most of the studies (such as Menage et al, 1992; Mousain-Bosc et al, 2006; Rimland et al 1978) reported that vitamin B6 combined with magnesium produced positive benefits on behaviour. For example, Menage et al, 1992 reported “Particularly, improvement was observed for certain autistic symptoms (lack of interest in people, abnormal eye contact, impairment in verbal and non-verbal communication).”
Two of these studies (Barthélémy et al, 1981 and Martineau et al, 1985) reported that vitamin B6 produced no effects by itself and that magnesium produced no effects by itself. However, when combined, vitamin B6 and magnesium produced a range of benefits. For example, Barthélémy et al, 1981 reported improvements in social interaction and social communication, as well as improvements in reactions to the environment.
Only one study (Kuriyama, et al, 2002) reported that vitamin B6 by itself (without magnesium) produced any kind of benefit (significant increase in verbal IQ scores).
Two of the studies (Findling et al, 1997; Tolbert et al, 1993) reported that vitamin B6 and magnesium produced no benefits on behaviour of any kind.