Multi-Vitamin and Mineral Supplements and Autism Ranking: Insufficient/Mixed evidence

Status Research

There are a number of significant limitations to all of the research studies published to date. For example

  • The study by Adams and Holloway (2004) was a small trial with only 25 participants (five of whom dropped out). The authors did not provide some key information, such as details of the dates that the trial ran, how the sample size was determined, details of the randomisation method used etc.The study did not report data on problem issues that the supplement was supposed to address (such as sleep problems and gastrointestinal problems) at the start of the study, only at the end.The tool used to collect this data was a very simple global impressions survey, based on parental observations of their children.There was no assessment of these issues by the study authors or by independent assessors.
  • The study by Mehl-Madrona et al (2010) was a retrospective case control study based on the medical records of a single medical practitioner.The parents chose which treatment their children received, the children who received medications rather than the supplement did not all receive the same medications (some received antipsychotics, some received antidepressants etc.), and the treatments received by some children changed considerably during the course of the study (for example, at the beginning of the study three children in the medication group were receiving mood stabilisers, at the end 16 children in the same group were receiving them). The children who received the supplement did not all receive the same formulation and some of them also began using omega fatty acid supplements (at the suggestion of the practitioner) or were using one or more other dietary supplements.
  • The study by Adams et al (2011) was a large trial with 141 individuals but it did not provide some key information, such as details of exactly where the trial took place, how the sample size was determined, details of the randomisation method used etc. In addition, the multi-vitamin/mineral supplement used in the trial contained levels of vitamin B6 that were well above recommended daily amounts (and could therefore have been dangerous) and also contained lithium (which is a mood stabiliser and could therefore have compromised any results).
  • The author of the study by Adams et al (2011) did not pay equal attention to all of the outcomes measures used in the way they wrote up their findings. This gave undue prominence to the one measurement tool which suggested that the supplement provided some significant benefits and failed to give sufficient prominence to the other tools which suggested that the supplement provided no benefits. The only assessment tool that found a significant difference between the supplement and the placebo was the PGI-R (Parental Global Impressions – Revised) and this tool was only used at the end of the study (whereas the others were used at the beginning and at the end). The PGI-R was the only tool mentioned in the summary and the conclusion of the study and was the only tool featured in three additional tables. The other assessment tools ATEC (Autism Treatment Evaluation Checklist), SAS (Severity of Autism Scale) and PDD-BI (Pervasive Development Disorder Behaviour Inventory) were hardly mentioned despite the fact that these tools found no significant differences between the supplement and the placebo. The authors should have made this fact much, much clearer in their reporting of the trial.  
  • The study by Adams et al (2011) was undertaken by researchers who were not independent of the intervention being studied. This is because some of the researchers are on the board of directors of a company called the Autism Nutrition Research Center which sells a product called ANRC Essentials. This is a dietary supplement based on the supplement used in the studies and which costs considerably more than most other multi-vitamin/mineral supplements. Some of the researchers involved in the study may therefore have been biased towards the intervention, however unconsciously.

For a comprehensive list of potential flaws in research studies, please see ‘Why some autism research studies are flawed’.

19 Dec 2017
Last Review
01 Nov 2017
Next Review
01 Nov 2020