Abstract

Aim: To investigate the change in core and associated behaviours of autism spectrum disorder (ASD) following micronutrient supplementation.

Methods: Adolescents and adults with ASD (N=16, aged 11-22) participated in an 8-week open label study of micronutrients supplements. Measures of behaviour and social responsiveness, using Autism Behaviour Inventory – Short (ABI-S) and Social Responsiveness Scale (SRS) respectively, were completed by parents and teachers at baseline and end of the study. Paired t-tests were used to compare the pre- and post-treatment mean scores.

Results: Eleven participants completed the study. Mean scores on both clinical outcomes showed improvements (decreases) over the study period, but none were statistically significant. Parent-reported ABI-S scores decreased (improved) by 11.5% (effect size=-0.52, p=0.08), teacher-reported ABI-S scores improved by 3.7% (effect size=-0.16, p=0.31), and parent-reported SRS scores improved by 8.6% (effect size=-0.56, p=0.05). There were no adverse events reported.

Conclusion: This study adds to the mixed findings of micronutrient supplementation in individuals with ASD, consistent with previous studies. Micronutrients were safely tolerated. In the future, randomized controlled trials with a larger sample size are needed to provide more insight on the potential benefits of micronutrients in ASD.

Keywords : Micronutrients, autism spectrum disorder (ASD), nutrition, supplements, clinical trial

Citation: Hossain, B., Benes, J., Bent, S., Widjaja, F., Parentau, C., Hendren RL. (2023). Micronutrient Supplementation in Adolescents and Adults with Autism Spectrum Disorder: An Open-Label Trial. Journal of Health and Rehabilitation Sciences, 2023 Oct 3; 2(2):30-39. https://doi.org/10.33700/jhrs.2.2.87

Copyright ©2023 Hossain, B., Benes, J., Bent, S., Widjaja, F., Parentau, C., Hendren RL. This is an open-access article distributed under the terms of the Creative Commons 4.0 International License (CC BY 4.0)

Bushra HOSSAIN

University of California, San Francisco,

Address: 675 18th St, San Francisco,

CA 94143, USA

Email: bushra.hossain@ucsf.edu

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by early deficits in social interactions and restricted, repetitive patterns of behavior, interests, or activities (American Psychiatric Association, 2013). The prevalence of ASD has been on the rise with the Centers for Disease Control (CDC) indicating a prevalence rate of 21.5 and 27.6 per 1,000 children aged 4 and 8, respectively (Shaw et al., 2023; Maenner et al., 2023). Additionally, the CDC estimates 2.21% of adults, over the age of 18, in the United States are on the spectrum (Dietz et al., 2020). To address these growing numbers, research efforts have increased to understand etiological factors contributing to ASD and identify potential interventions.

Among these, nutritional supplementation has been an area of focus. Previous studies have revealed imbalances in vitamins and minerals in children and adolescents with ASD, including lower levels of vitamin D, lithium, zinc, and methionine, along with elevated levels of vitamin B6, C, and beta-carotene (Adams et al., 2011a). These nutritional imbalances may contribute to impaired methylation, decreased glutathione levels, and increased oxidative stress, possibly playing a role in the presentation of ASD symptoms (Adams et al., 2011a). Furthermore, nutritional deficiencies have been found to increase the risk of ASD (Wang et al., 2020; Alzghoul et al., 2020) and exacerbate core symptoms (Cheng et al., 2020). A comparative study by Zhu et al. (2020) demonstrated correlations between insufficient micronutrient levels and the development of ASD, along with associated symptoms, in children.

The high incidence of this nutritional vulnerability in ASD has been associated with poor dietary patterns, such as consuming less varied diets and limited fruits and vegetables (Chistol et al., 2018). With these nutritional and dietary considerations, there are probable functional consequences. Gastrointestinal symptoms, such as diarrhea, constipation, and abdominal pain, are common among individuals with ASD, potentially affecting nutrient absorption and the composition of their gut microbiome (McElhanon et al., 2014). These gastrointestinal disturbances are thought to play a role in modulating the expression of social and behavioral symptoms (Karhu et al., 2020).

Various complementary and alternative interventions have been explored as possible therapies for the clinical symptoms of ASD. Several studies evaluating the efficacy of nutritional interventions in individuals with ASD showed nutritional supplementation to be effective in improving several symptoms, functions, and clinical domains (Adams et al., 2018; Fraguas et al., 2019; Kittana et al., 2021; Song et al., 2020;) or provided inconsistent results (Li et al., 2018; Monteiro et al., 2020). Another study assessing how nutritional interventions may affect other developmental disorders found clinical benefits of micronutrient supplementation in Attention Deficit/Hyperactivity Disorder (ADHD), which may translate as an effective intervention for ASD (Johnstone et al., 2022).

Prior studies studying the effects of micronutrient supplementation in individuals with ASD have shown some promising findings. One study found autism severity scores to correlate with levels of vitamins, minerals, and amino acids (Adams et al., 2011a). A double-blind, randomized, placebo-controlled trial of a vitamin/mineral supplement in 141 children with autism found numerous improvements in nutritional biomarkers as well as a statistically significant improvement in parent ratings of child functioning (with specific questions on language, behavior, social function, sleep, gastrointestinal symptoms, and eye contact). There was no improvement in the Social Responsiveness Scale (SRS) or the Pervasive Developmental Disorder Behavior Inventory (PDD-BI) (Adams et al., 2011b). A more recent open-label study by the same team collected evaluations from 161 people with autism about the effectiveness of the vitamin/mineral supplement from the double-blind RCT (Adams et al., 2022). When compared to the placebo group of the previous study, the participants of the open-label study had greater improvements in parent-reported child functioning across a wide range of symptoms. Another study from the group evaluated a more complex intervention that included a nutritional supplement as well as digestive enzymes, carnitine, essential fatty acids, Epsom-salt baths, and a healthy gluten-free, casein-free, soy-free diet. The study found improvements in autism symptoms but was limited by the single-blind study design (Adams et al., 2018).

Despite the potentially beneficial results, these studies were limited in design - open-label or single-blind for most - and were few in number, only four studies by the same group. Therefore, there exists the need for more research examining the effect of micronutrient supplementation in individuals with ASD. The current study aims to investigate the changes in clinical outcomes before and after micronutrient supplementation in adolescents and adults with ASD. Understanding the potential impact of micronutrient treatment on clinical outcomes can aid in developing effective therapies for ASD. By addressing this research question, the present study seeks to fill the existing knowledge gap and shed further light on micronutrient supplementation in individuals with ASD.

Sixteen students enrolled in the school completed the informed consent process for the study. Four participants withdrew before completing post-baseline information due to the inability to take the micronutrients supplements as instructed. They all withdrew earlier on in the study; two participants withdrew after two days, one after one week and one after two weeks. None of them could tolerate the sensation of the powder form and therefore could not take the micronutrients. Another participant was lost to follow-up early on in the study (shortly after the baseline visit) despite numerous attempts to reach them throughout the study period. (Figure 1). The characteristics of the 11 participants who completed the study are shown in Table 1. All participants had a diagnosis of ASD, 82% were male and the mean age was 17.7 years. Neither of the participants who were taking medications had any changes in their medications during the course of the 8-week study period. None of the participants reported any adverse events during the study period.

Fig. 1: Flow of participants through the study

Table 1: Characteristics of participants who completed the study

Individuals with ASD have been known to have nutritional deficiencies and prior studies have indicated that there may be clinical benefits to micronutrient supplementation. As such, we sought to examine any changes in clinical symptoms after micronutrient supplementation in adolescents and adults with ASD through an open-label clinical trial. Overall, there were no significant changes in the mean score of ABI-S and SRS at the end of the study compared to baseline, although there were some improvements at the individual level. Namely, among the eleven participants, six were considered responders and five were non-responders.

A small number of studies have studied micronutrient supplementation in ASD with potentially promising results. These include levels of vitamins, amino acids and minerals correlating with autism severity scores (Adams et al., 2011a), significant improvements in ratings of functioning across a number of different symptoms (Adams et al., 2011b; Adams et al., 2018; Adams et al., 2022). The findings from our study that showed no significant change in mean clinical symptoms after micronutrient supplementation contradict the (albeit limited) clinical benefits seen in these previous studies.

Although our results did not achieve statistical significance, we did see a trend towards improvement in ABI-S and SRS, mainly among parent-reported surveys which had moderate effect sizes. One reason for the negative findings could be the small sample size and resulting lack of power. Another could be that our study duration (8 weeks) was too short, and the micronutrients needed more time to show a significant effect. In contrast, all prior studies in this population were at least 12 weeks long.

Another interesting aspect of our findings was that parent-reported measures showed a greater absolute improvement compared to teacher-reported measures. One reason for this could be that the teacher ratings were influenced by comparison with other students in the class, whereas the parents did not have such a comparison point.

Although micronutrient supplementation in ASD has not been studied in detail, there have been some studies investigating general nutritional supplements in ASD populations, often showing mixed results. A meta-analysis (Fraguas et al., 2019) looking at specific dietary interventions on the symptoms, functions, and clinical domains in subjects with ASD found them to exert a nonspecific and small effect in ASD.

When looking at vitamin supplementation specifically, they observed small but statistically significant improvements in most of the outcomes measured. A more recent narrative review (Poudineh et al., 2020) looking at the effects of vitamins and other dietary supplements on ASD concluded that vitamins A, B6, B12, and D, iron supplements, L-carnosine, melatonin, Omega-3 and serotonin had growing positive evidence and thus showed some promise. However, the effects of multivitamin/mineral supplements, vitamin C, chelation, cyproheptadine, magnesium supplements, tryptophan and zinc supplements need further evaluation due to insufficient evidence.

Similarly, a systematic review (Li et al., 2018) also had mixed findings, where folinic acid and methyl B12 showed some improvements in ASD severity, vitamin D3 had inconsistent results in behavioral outcomes, and vitamin B6/Mg and omega-3 fatty acid were not helpful improving ASD symptoms. Another systematic review (Sathe et al., 2017) found methyl B12 and levocarnitine to show some improvement in symptoms severity and gluten/casein-free diets to have parent-rated improvements in communication and challenging behaviors, while omega-3 fatty acid did not affect challenging behaviors.

However, the authors observed insufficient or low strength of evidence for most of the studies. The consensus from prior literature is that while nutritional and dietary supplements show some promise in managing ASD symptoms, the results are mixed and inconsistent. Therefore, further research is required on this topic.

The micronutrient supplement used in this study was well-tolerated, as none of the participants who completed the study reported any adverse events during the course or at the end of the study. The micronutrients supplement used in this study was much lower in dose across all vitamins and minerals compared to the micronutrients used in the previous studies. The absence of adverse reactions aligns with other studies of micronutrients in ASD populations, which also observed them as safe and tolerable (Adams et al., 2011b; Adams et al., 2018; Adams et al., 2022). Interestingly, in a recent review summarizing the current evidence for using vitamins, minerals, and cofactors in ASD, Indika et al. (2023) cite that while some supplements have been studied in RCTs as monotherapy, few studies have used multinutrient supplements or studied the effectiveness of their combination in ASD. They propose that using a combination of vitamins may have advantages over monotherapy, including higher bioavailability, synergistic action and reduced adverse effects due to high doses. In that regard, our study adds to the few others that have used multiple nutrients over single nutrient treatment and also shows its safety and tolerability. Identifying a treatment biomarker to target with specific micronutrients may also improve statistical significance.

In interpreting the findings of this study, several limitations should be acknowledged. Firstly,the limited sample size (N=11) has indeed constrained the statistical power of the analysis and, therefore, it affects the generalizability of the results.

A larger sample size would provide more insights into the effects of micronutrient supplementation on clinical outcomes in individuals with ASD. Secondly, the absence of a control group prevents direct comparisons between treated participants and untreated individuals, limiting our ability to isolate the effects of the micronutrient supplement from other confounding factors.

A well-matched control group would have allowed for a more comprehensive evaluation of treatment efficacy. Finally, we do not have information regarding the types of diets the participants were on, especially if they were on any special or limited diets, which could have influenced their response to the micronutrient supplementation.

Despite these limitations, this study contributes valuable insights into the potential benefits of micronutrient supplements in individuals with ASD. It is one of the few studies that examined micronutrient supplementation in this population and showed trends towards improvement in clinical outcomes and the safety and tolerability of the treatment in this population. The small sample size and absence of a control group certainly warrant caution in the interpretation of the results but also highlight the need for future research with a larger number of participants and appropriate control groups. By addressing these limitations, subsequent studies may achieve a better understanding of the effects of micronutrient supplementation on clinical outcomes in ASD, further enhancing the potential for targeted and effective interventions for this population. Acknowledgements: We would like to thank JS Foundation for funding this study. We are also grateful to TrueHope Nutritional Support Ltd. for supplying the micronutrient supplements.

Conflicts of interest

The authors declare that they have no conflicts of interest.

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