Updated by
Lisa Tereshko, PhD, BCBA-D, Endicott College
Joyce Mauk, MD, Burnett School of Medicine at TCU and Austin College

Description:

Autism Treatments SummaryThere is a hypothesis that individuals with autism spectrum disorder (ASD) have higher levels of toxic heavy metals in their systems than their peers (Lagan & Balfe, 2018); however, this hypothesis is unproven. This is thought to be related to mercury in vaccines. It has been suggested (but not proven) that the severity of ASD is directly related to the amount of toxic heavy metals in the individual’s system. Therefore, the theory behind chelation is that the removal of the metals will decrease the severity of ASD. Chelation is a procedure that works to remove heavy metals (e.g., mercury and/or lead) from the body through the oral consumption or intravenous injection of assorted chemical substances that bind to the metals in the body for excretion via a person’s urine (Brondino et al., 2015; James et al., 2015). The substances used sometimes consist of disodium ethylenediaminetetraacetic acid (EDTA), dimercaptosuccinic acid (DMSA), or leuprolide acetate (Brondino et al., 2015; Mitka, 2008).

Chelation has been approved to treat patients with verified heavy metal poisoning (i.e., lead poisoning), but is not approved for patients with other diseases and disorders (e.g., Alzheimer’s disease, coronary heart disease, ASD; James et al., 2015). Chelation has utility in the treatment of specific conditions, such as lead poisoning (James et al., 2015). In these contexts, when the toxicity is documented, chelation can help reduce toxic levels of the substances within the body. However, there is no known association between heavy metal toxicity and autism. Some companies attempt to sell various chelation drugs over the counter as dietary supplements or as an over-the-counter chelation medication for individuals with ASD, but the U.S. Food and Drug Administration (FDA) has warned companies against doing so as it is dangerous and illegal (Voelker, 2010). The risk of taking chelation drugs without a prescription for an approved diagnosis (i.e., lead poisoning) can result in serious side effects (Voelker, 2010).

Chelation is not a benign intervention; it is associated with many adverse and potentially harmful side effects. Some of the side effects noted in the research include rash, gastrointestinal upset, generalized toxicity, fatigue, hypocalcemia (low calcium levels), thrombophlebitis (increased blood clots), nausea, dysgeusia (distorted metallic taste), nephrotoxicity (toxicity of the kidneys), and even death (James et al., 2015).

Research Summary:

There is no evidence to support the utility of chelation in the treatment of autism. In 2008, the federal government canceled enrollment of clinical trials that were designed to test the effects of chelation for the treatment of ASD (Mitka, 2008). Furthermore, the National Institute of Mental Health (NIMH) canceled its study investigating chelation with individuals with ASD due to an increased risk for participants and marginal confidence that it would have a positive effect on symptoms. Given these concerns, there has been a reduction in investigations researching the effects of chelation on the ASD population.

Researchers have conducted systematic literature reviews to reassess past findings on chelation to help determine the effect it has had on the ASD population. Only a few articles were identified in each of the reviews due to the limited research conducted on chelation with individuals with ASD (Davis et al., 2013 [five articles]; Höfer et al., 2017 [20 articles]; James et al., 2015 [one article]; Lagan & Balfe, 2018 [two articles]). Furthermore, across all reviews, only a small percentage of articles identified supportive evidence (i.e., only two studies across all reviews identified positive effects and these articles lacked experimental designs, limiting these conclusions). Across the systematic literature reviews found, one article (Adams et al., 2009) was identified in three of the reviews (Davis et al., 2014; James et al., 2015; Lagan & Balfe, 2018). All reviews that assessed the study by Adams et al. (2009) agreed chelation offered no benefit.

The review with the most articles identified was Höfer et al. (2017) which reviewed chelation more broadly by examining studies that used complementary alternative medicine as an intervention for ASD. They identified 20 articles for inclusion and 15 of those studies used chelation in combination with other complementary alternative medicine approaches. The researchers concluded that evidence for the majority of treatment packages that included chelation was low, with a risk of adverse and potentially harmful effects.

Articles assessed across the reviews had a variety of limitations that reduced the quality of their findings. A variety of dependent measures were assessed across the studies to examine the effects on the symptoms of ASD. Along with medical measures (i.e., blood and/or urine sampling), their measures included anecdotal parental reports, researcher-made surveys, and formalized checklists (i.e., Autism Treatment Evaluation Checklist). All studies were completed with insufficient certainty of evidence as there was either no experimental design or no control group. As such, the existing studies do not have the level of experimental rigor or protection from bias that constitutes good scientific investigations. Consequently, Davis et al. (2013) concluded that the evidence for the use of chelation to treat the symptoms of ASD is extremely weak.

Recommendations:

Chelation has been proven helpful for treating those with acute heavy metal toxicity. There is no supported use of chelation for any condition other than heavy metal poisoning. Chelation is not relevant to the treatment of autism and poses significant potential harm, and can result in loss of life. The National Center for Complementary and Alternative Medicine (NCCAM) has stated that the use of chelation for nonapproved diseases and disorders has led to approximately 800,000 physician visits annually furthering the strain on the medical system (Mitka, 2008).

Some individuals have suggested that individuals with autism have metal toxicity from vaccines. The suggestion that mercury in vaccinations is the cause of ASD has been disproven through multiple epidemiological studies (Institute of Medicine Immunization Safety Review Committee, 2004; Schultz, 2010), but some physicians and websites continue to recommend chelation to remove mercury for individuals with ASD (Brent, 2013). There is no basis for this recommendation; it is not supported by evidence and is dangerous.

Despite reports of adverse side effects and harm, the termination of studies due to safety concerns of participants, and the discouragement of physicians, chelation continues to be used as an autism treatment (James et al., 2015). There is no high-quality evidence that suggests chelation is effective in improving symptoms of ASD (James et al., 2015). The validity and quality of the studies conducted on chelation are poor, and the premise of chelation’s relevance for autism is also flawed. The weak quality and validity of studies, the absence of a rationale for the implementation of chelation as an ASD intervention, and the potential for extreme adverse side effects strongly argue against the use of chelation as an intervention with individuals with ASD (Davis et al., 2013; James et al., 2015; Lagan & Balfe, 2018; Mitka, 2008; Voelker, 2010). Chelation is not an intervention that should be considered for autism, and its use poses great risk to individuals with autism.

Selected References

Systematic Reviews and Task Forces

Davis, T. N., O’Reilly, M., Kang, S., Lang, R., Rispoli, M., Sigafoos, J., Lancioni, G., Copeland, D., Attai, S., & Mulloy, A. (2013). Chelation treatment for autism spectrum disorders: A systematic review. Research in Autism Spectrum Disorders, 7, 49-55. http://dx.doi.org/10.1016/j.rasd.2012.06.005

James S., Stevenson S. W., Silove, N., & Williams K. (2015). Chelation for autism spectrum disorder (ASD) (Review). Cochrane Database of Systematic Reviews, 5. https://doi.org/10.1002/14651858.CD010766.pub2

Höfer, J., Hoffmann, F., & Bachmann, C. (2017). Use of complementary and alternative medicine in children and adolescents with autism spectrum disorder: A systematic review. Autism, 21(4), 387-402. https://doi.org/10.1177/1362361316646559

Schultz, S. T. (2010). Does thimerosal or other mercury exposure increase the risk for autism? A review of current literature. Acta Neurobiologiae Experimentalis, 70(2), 187–195. https://doi.org/10.55782/ane-2010-1790

Selected Scientific Studies

Adams, J. B., Baral, B., Geis, E., Mitchell, J., Ingram, J., Hensley, A., et al. (2009). Safety and efficacy of oral DMSA therapy: Part B—Behavioral results. BMC Clinical Pharmacology, 9. https://doi.org/10.1186/1472-6904-9-17

Other Works Cited Above

Brent, J. (2013). Commentary on the abuse of metal chelation therapy in patients with autism spectrum disorders. Journal of Medical Toxicology, 9, 370-372. https://doi.org/10.1007/s13181-013-0345-4

Brondino, N., Fusar-Poli, L., Rocchetti, M., Provenzani, U., Barale, F., & Politi, P. (2015). Complementary and alternative therapies for autism spectrum disorder. Evidence-Based Complementary and Alternative Medicine, 2015, ID 258589. https://doi.org/10.1155/2015/258589

Institute of Medicine (US) Immunization Safety Review Committee. (2004). Immunization safety review: Vaccines and autism. National Academies Press (US). https://doi.org/10.17226/10997

Lagan, N. C., & Balfe, J. (2018). Question 2: Does heavy metal chelation therapy improve the symptoms of autism spectrum disorder. Archives of Disease in Childhood, 103(9), 910-911. https://doi.org/10.1136/archdischild-2018-315338

Mitka, M. (2008). Chelation therapy trials halted. Journal of the American Medical Association, 300(19), 2236. https://doi.org/10.1001/jama.2008.607

Voelker, V. (2010). FDA warning targets OTC chelation products. Journal of the American Medical Association, 304(19), 2112. https://doi.org/10.1001/jama.2010.1654.

Citation for this article:

Tereshko, L., & Mauk, J. (2024). A treatment summary of chelation. Science in Autism Treatment, 21(4).

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