Research Brief: Sulforaphane and Autism
Autism spectrum disorder (ASD) is a developmental disorder characterised by impaired communication and social interactions. Children with ASD also often have abnormal behaviours, interests and play.
The incidence of ASD in Australia is 1 in 150 people and it is more common in males than females. The clinical presentation of no two individuals with ASD are exactly the same, although they may have similar behavioural traits. Autism is referred to as a spectrum disorder as there are mild, moderate or severe forms of ASD, and within those forms individuals can experience different features. There is currently no reliable biological test for ASD, instead it is diagnosed based on the professional observation of particular behaviours.
The exact cause of autism is still unknown, however it is understood to be the result of a combination of genetic, environmental and developmental factors. While there is lots that can be done to support individuals with ASD, there is currently still no documented, mechanism based treatment or cure. Early intervention and support can have a significant difference in helping individuals with ASD reach their full potential and depending on the symptoms and the severity of ASD, medications may be prescribed. However, many of the medications prescribed can result in unpleasant side effects such as drowsiness, increased appetite and hormonal changes.
In addition to pharmaceutical interventions, more research is now being done on nutritional therapeutics and their potential to address some of the underlying mechanisms of ASD. One particular therapeutic that has recently been researched in a number of clinical trials researched is sulforaphane.
Sulforaphane is a isothiocyanate compound derived from the broccoli plant. In broccoli, it is in the inactive form of glucoraphanin and is then activated to sulforaphane when glucoraphanin comes into contact with myrosinase enzymes. Myrosinase enzymes are only released and activated when a plant is damaged, therefore the broccoli must be cut, chopped or well-chewed to release the myrosinase and activate sulforaphane.
Sulforphane has been extensively studied and research has found sulforphane to have a number of beneficial health effects. The therapeutic potential of sulforphane is based on its powerful ability to protect cells by up regulating the various protective systems within cells that reduce the risk of damage and therefore the development malignancies and other chronic conditions.
Researchers have started to investigate sulforphane as evidence has shown that sulforphane counteracts many of the same biochemical and molecular abnormalities that are associated with ASD, such as oxidative stress, neuroinflammation, defects in glutathione synthesis, mitochondrial dysfunction, reduced antioxidant capacity and increased lipid peroxidation. Although it is still unclear whether these abnormalities are the cause of ASD, or secondary manifestations of ASD, studies have shown that their correction improves behaviour in those with ASD.
Sulforaphane Treatment in Autism Spectrum Disorder
The study covered in this research brief was a placebo-controlled, randomised, double blind clinical trial (basically the gold standard of studies) that assessed the benefits of orally administered sulforphane derived from broccoli sprouts completed in 2014.
The trial observed 44 young men with ASD over 18 weeks, 29 received the sulforphane and 15 received an identical placebo.
The study found some very positive outcomes in the sulforphane group, with notable improvements being noted on laboratory scores and reports from parents/caregivers starting from week 4 of the study.
The study showed the following results in patients who received the sulforphane:
Improvements in social interaction
Reductions in aberrant/abnormal behaviour
Increase in verbal communication
Significantly greater improvement observed for irritability, lethargy and hyperactivity
Parents and caregivers of the placebo group stated no signs of improvement in any area of communication or social behaviours. Interestingly, positive responses to sulforphane were spontaneously reported from week 4 onwards (despite parents still being unaware whether their child was receiving sulforphane or a placebo), particularly in relation to social responsiveness and calmness.
Adverse Reactions and Safety
This study showed that sulforphane was generally safe and well tolerated by the boys in the study. However the study did find that the boys that received the sulforphane did put on more weight over the 18 week study than those who received the placebos, and their pulse rates were slightly lower.
Vomiting, increased aggressions, abdominal pain, flatulence, constipation, headaches, diarrhoea, fever and allergies were reported in 12% of the patients in the sulforphane group, but interestingly, the same percent of the placebo group also reported these symptoms. As these symptoms are commonly experienced by people with ASD and both groups reported them, it was concluded that this wasn’t a direct result of the sulforphane.
Two of the patients that received the sulforphane did have a seizures, one three weeks into the study and one 3 weeks after finishing the study. Although patients with ASD are of an increased risk of seizures, at this stage we cannot rule out the possibility of seizures as an adverse effect of sulforphane in ASD patients.
The behavioural outcome measures used and the clinical observations by study physicians and the parents/caregivers all indicated that many of the patients who received sulforphane had statistically significant and clinically meaningful improvements during their treatment with sulforphane. The apparent improvements strongly suggest that further investigation of sulforphane in ASD is both valuable and promising.
As this study was just focusing on boys, we aren’t sure if sulforphane supplementation would have the same beneficial effects in girls with ASD. However, the paper showed great outcomes for many of the boys receiving sulforphane in the study, so hopefully more studies will be done on a bigger group that also includes girls.
It is important to remember that although sulforphane is a naturally occurring compound in food that is easily accessible, the supplementation or use of it as a therapeutic intervention still needs to be discussed and approved by your child’s physician.
Bent, S., Lawton, B., Warren, T., Widjaja, F., Dang, K., Fahey, J. W., … Hendren, R. L. (2018). Identification of urinary metabolites that correlate with clinical improvements in children with autism treated with sulforaphane from broccoli. Molecular Autism, 9(1). doi:10.1186/s13229-018-0218-4
Lynch, R., Diggins, E. L., Connors, S. L., Zimmerman, A. W., Singh, K., Liu, H., … Fahey, J. W. (2017). Sulforaphane from Broccoli Reduces Symptoms of Autism: A Follow-up Case Series from a Randomized Double-blind Study. Global advances in health and medicine, 6, 2164957X17735826. doi:10.1177/2164957X17735826
Singh, K., Connors, S. L., Macklin, E. A., Smith, K. D., Fahey, J. W., Talalay, P., & Zimmerman, A. W. (2014). Sulforaphane treatment of autism spectrum disorder (ASD). Proceedings of the National Academy of Sciences of the United States of America, 111(43), 15550–15555. doi:10.1073/pnas.1416940111