High-dose pyridoxine and magnesium administration in children with autistic disorder: an absence of salutary effects in a double-blind, placebo-controlled study.
High-dose vitamin B6 and magnesium did not improve autism behaviors in a ten-week blinded trial.
01Research in Context
What this study did
Christian et al. (1997) gave children with autism either high-dose vitamin B6 plus magnesium or a placebo pill every day for ten weeks.
The team used a double-blind design, so no one knew which pill each child got. They measured autistic behaviors before and after.
What they found
At the end of the study, the vitamin group looked the same as the placebo group. The vitamins did not help any autism behaviors.
How this fits with other research
Ramírez-Guerrero et al. (2025) looked at many antioxidant studies and also found no strong win for any single supplement. Their review includes this 1997 trial, showing the null result still holds almost thirty years later.
Laposa et al. (2017) showed that parents often report big "gains" even when nothing was given. That placebo-like effect helps explain why vitamins can look helpful in open-label stories but fail in blinded tests like this one.
Moerkerke et al. (2024) tested oxytocin the same way and also saw no drug benefit over placebo. The pattern is clear: well-controlled autism drug trials usually come up empty.
Why it matters
Families still ask about B6 and magnesium. You can tell them a blinded study found zero benefit. Save your treatment hours for evidence-based teaching strategies and skip the supplement chase unless new data appear.
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02At a glance
03Original abstract
Several reports have described salutary effects such as decreased physical aggression and improved social responsiveness being associated with the administration of high doses of pyridoxine and magnesium (HDPM) in open-labeled and controlled studies of patients with autism. Despite this fact, this intervention remains controversial. A 10-week double-blind, placebo-controlled trial was undertaken to examine both the efficacy and safety of HDPM in autism. Twelve patients were enrolled, and 10 patients (mean age 6 years 3 months) were able to complete the study. HDPM at an average dose of 638.9 mg of pyridoxine and 216.3 mg of magnesium oxide was ineffective in ameliorating autistic behaviors as assessed by the Children's Psychiatric Rating Scale (CPRS), the Clinical Global Impression Scale, and the NIMH Global Obsessive Compulsive Scale. Furthermore, no clinically significant side effects were noted during HDPM administration. A trend for a transient change on the CPRS was found that was possibly due to a placebo response. This study raises doubts about the clinical effectiveness of HDPM in autistic disorder.
Journal of autism and developmental disorders, 1997 · doi:10.1023/a:1025861522935