Omega-3 fatty acids—Grade: B
Polyunsaturated fatty acids, in particular omega-3 fatty acids, are crucial for brain development and cannot be manufactured in the body. Essential fatty acid supplements such as fish oil have become popular for children with autism. A recent randomized, double-blind, placebo-controlled, six-week pilot study found behavior improvements in 13 children with severe behavior problems as a result of autism.
Folic acid—Grade: C
Oxidative stress is a theory that some people have advanced to account for the atypical brain development seen in autism, and abnormal levels of antioxidants have been reported in children with autism. But there are no randomized, controlled trials testing the notion that supplementation with folic acid, a water-soluble B vitamin that helps produce and maintain new cells, would have beneficial effects.
Secretin, a gastrointestinal hormone, is one of the most extensively studied autism treatments. More than a dozen well-designed, well-executed studies have failed to find any benefit.
Parent reports of frequent respiratory or gastrointestinal infections in children with autism are used to support the theory that the children have immune system problems, but those findings have not been confirmed. One study found short-term behavioral improvement in 11 children treated with oral vancomycin. But there are no other data supporting the use of antibiotics, and the researchers in that study said they would not recommend it for routine treatment.
Antifungal agents—Grade: C
Treatment with antifungal agents is based on the premise that imbalances in intestinal flora or other immune factors lead to an overgrowth of yeast. No controlled trials have tested antifungals as an autism treatment despite the popularity of medications such as nystatin (Mycostatin) and fluconazole (Diflucan).
Gastrointestinal medications—Grade: C
Children with autism frequently have symptoms such as reflux, constipation and diarrhea, and eat only a very limited number of foods. There are no evidence-based studies on the efficacy of digestive enzymes or probiotics for treating these symptoms.
Hyperbaric Oxygen Therapy—Grade: C
Hyperbaric oxygen therapy (HBOT) is used in conventional medicine to treat carbon monoxide poisoning and to speed wound healing, and it has become popular as an autism treatment based on theories that implicate gut or brain inflammation or lack of blood flow to the brain. There are no randomized clinical trials of HBOT for autism. One open trial of 18 children with autism found some decrease in C-reactive protein, a marker for inflammation, and parents reported improved behavior. But the subjective measures and the fact that many of the children were also taking antioxidant supplements "make this study difficult to interpret," Hyman and Levy report.
Immune therapies—Grade: C
Some alternative practitioners recommend treatment with intravenous immunoglobulin-G, on the premise that immune deficits cause symptoms of autism. One open trial reported subjective improvements, but two other trials with specific outcome measures found no benefit.
One alternative theory holds that mercury is poorly eliminated by children with autism, and that the toxic metal alters immune function and development. Epidemiological studies have failed to find a link between the use of the ethyl mercury–based preservative thimerosal in vaccines and autism. Despite this, chelation, the standard treatment for heavy metal poisoning, is marketed as an off-label treatment for autism. There are no controlled studies testing chelation's safety or effectiveness as an autism treatment, and at least one child has died after being treated with EDTA (ethylenediamine tetraacetic acid) chelation for autism.