by Bianca Garilli, ND, IFMCP
Across the world autism spectrum disorder (ASD) rates vary greatly; making it difficult to confirm definitive numbers particularly in many countries that do not actively track rates or publicly report their statistics. However, data from countries such as Poland where it is reported that 3 in 10,000 children are diagnosed with ASD, or Hong Kong where ASD afflicts 327 in 10,000 children and in the US where in 2015 there were 222 in 10,000 children or 1 in 45 are affected,1 are all alarming numbers and should be a wake up call for clinicians.
ASD may occur with, or without, intellectual disability (ID) where ID is defined as an IQ of less than 70.2 Living with a diagnosis of ASD can be difficult for both the child and the family due to the deficits which define this diagnosis. These include difficulties with social skills, repetitive behaviors, and challenges with speech and non-verbal communication. Bowel diseases are higher in the ASD population and many suffer extreme anxiety. Epilepsy has also been shown to affect 20% of children with ASD, and a host of other emotional, social and psychological concerns often coexist with this diagnosis.1
Research indicates various potential influences on the development of autism regardless of ID. These include influences on the gestational environment such as fetal growth deviance, maternal infection and inflammation, and maternal exposure to environmental toxins. Heritability has also been shown to play a role in the development of ASD and is estimated to be 0.50 and shared familial environmental influences to be 0.04.3-4
More recently, studies have looked at nutritional supplementation of the mother during pregnancy and how this may affect risk of ASD in the fetus or newborn. Some studies indicate a micronutrient deficiency due to maternal exposure to environmental toxins may lead to increased risk of ASD in the unborn child whereas maternal nutritional supplementation during pregnancy may reduce those risks.5 Two frequently researched nutrient deficiencies studied for their potential influence on ASD risk are folic acid and iron; studies looking at the effects of supplementing with these nutrients during pregnancy have found a reduced risk of ASD in the child.6
An observational, prospective, cohort study published in BMJ in 2017 analyzed data collected from 273,107 mother-child pairs from Sweden born between 1996 and 2007.7 The information gathered for this study included the pregnant women’s self-reported utilization of supplements and drugs at the time of their first antenatal visit. Supplementation use was categorized into the following groups: multivitamin (MV), iron, iron and folic acid, folic acid alone or no supplementation. The MV category was further broken down into MV alone; MV and iron; MV and folic acid; and MV plus iron and folic acid. Additionally, ASD statistics for the offspring of these mothers was collected and the data was broken down into two additional categories: ASD with ID and ASD without ID. Results from this study include the following:7
- MV use was associated with a lower likelihood of ASD with ID compared with non-use of MV, iron and folic acid, but was not associated with ASD without ID in any of the analysis
- Iron use was not associated with ASD with or without ID in any of the analysis
- Folic acid results suggest there may be an increased association between folic acid use and ASD without ID
The results from this study underscore the complexity of understanding the role of supplementation in the human body and more so when combined with a myriad of environmental and genetic factors. The authors called out a few of the potential confounding factors associated with the findings from this study; many of which may account for why these types of studies often result in conflicting outcomes. These factors may include:
- Mother’s nutritional status and dietary habits
- Brand, dosing, timing and formulation of supplements
- Consistency of use of supplementation
- Presence of a “window of exposure” for each of the supplements studied
- Susceptibility and risk factors associated with different nationalities
- Differences in nutritional fortification in various countries 7
In summary, this study and several others have noticed a possible reduction in ASD risk associated with maternal vitamin supplementation use. A 2018 study in JAMA Psychology8 corroborates the 2017 BMJ findings. In the 2018 case-control cohort study, 45,300 Israeli children born between January 1, 2003 and December 31, 2007 were followed from birth through January 2015. The data collected from the study found that maternal exposure to folic acid and multivitamin supplementation before and during pregnancy was associated with a reduced risk of ASD when compared to offspring of mothers without this supplementation use.8
In summary, research has indicated a potential benefit of nutritional supplementation in women during antenatal and prenatal time periods in reducing risk of ASD in their offspring.
Why is this Clinically Relevant?
- MV use should be discussed at all antenatal and prenatal visits
- Nutritional status testing may uncover important and critical nutritional deficiencies before and during pregnancy
- Nutritional deficiencies should be treated through personalized diet and nutritional supplementation recommendations and nutrient levels followed throughout pregnancy
- Healthcare providers should continue to follow recommended guidelines for nutritional supplementation in pregnancy as set out by country specific health organizations
- Charron R. For for Health. Autism rates across the developed world. https://www.focusforhealth.org/autism-rates-across-the-developed-world/. Accessed January 28, 2018.
- Chapman T et al. IQ in children with autism spectrum disorders: data from the Special Needs and Autism Project (SNAP). Psychol Med. 2011;41(3):619-27.
- Xie S et al. Prevalence of autism spectrum disorders with and without intellectual disability by gestational age at birth in the Stockholm Youth Cohort: a register linkage study. Paediatric and Perinatal Epidemiology. 2017;31:586–594.
- Sandin S et al. The heritability of autism spectrum disorder. JAMA. 2017;318(12):1182-1184.
- Nuttall JR. The plausibility of maternal toxicant exposure and nutritional status as contributing factors to the risk of autism spectrum disorders. Nutr Neurosci. 2017;20(4):209-218.
- Schmidt RJ et al. Maternal intake of supplemental iron and risk of autism spectrum disorder. Am J Epidemiol. 2014;180(9):890-900.
- DeVilbiss E et al. Antenatal nutritional supplementation and autism spectrum disorders in the Stockholm youth cohort: population based cohort study. BMJ. 2017; 359:j4273.
- Levine SZ et al. Association of maternal use of folic acid and multivitamin supplements in the periods before and during pregnancy with the risk of autism spectrum disorder in offspring. JAMA Psychiatry. 2018;75(2):176-184.