Link between daily diet soda and aspartame intake in early life with autism in males

In a recent study published in Nutrients, researchers investigated the association between maternal daily consumption of diet sodas or aspartame during pregnancy and the risk of autism in offspring.

Study: Daily Early-Life Exposures to Diet Soda and Aspartame Are Associated with Autism in Males: A Case-Control Study. Image Credit: VintageTone/Shutterstock.com

Background

Over the past four decades, autism spectrum disorder (ASD) diagnoses in the United States (US) have surged, especially among males. While diagnostic changes and increased testing partly explain this rise, maternal dietary factors, including aspartame consumption, have been identified as potential influences.

Aspartame, a prevalent sweetener, breaks down into metabolites that may affect neurological function, and its safety and impact on neurological health have been debated for years. 

About the study

The Autism Tooth Fairy Study, executed from 2011 to 2014 at the University of Texas Health Science Center at San Antonio (UTHSCSA), primarily sourced participants from the Interactive Autism Network (IAN).

The IAN registry comprised 21,600 individuals diagnosed with ASD and their parents; 356 children-235 with ASD and 121 controls participated in the study.

Parents provided demographic data and information on any ASD-related diagnoses their children received. Children diagnosed with specific ASD forms were labeled as cases, while those without developmental issues were controls; the study also examined their speech regression patterns.

A significant component of the study was mothers’ recall of their consumption habits during pregnancy and breastfeeding, specifically concerning diet drinks and low-calorie sweeteners, such as Sweet ‘N Low, Equal, and Splenda.

The study had two main focal points: identifying autism disorders and any ASD type. Emphasis was placed on evaluating the early-life exposure of offspring to aspartame and other non-nutritive sweeteners.

They utilized multilevel mixed-effects generalized linear models for data analysis and determined odds ratios for directions to certain products.

Lastly, a sensitivity analysis explored the correlation between demographic factors like income, education level, ethnicity, and maternal consumption patterns. They used the Stata/IC 14.2 software for statistical analysis, highlighting any significant disparities among demographic subsets.

Study results 

In the Autism Tooth Fairy Study, the sample composition included 257 boys, with 203 diagnosed with ASD and 54 as controls. There were 99 girls, of which 32 had ASD diagnoses, and 67 were controls.

Maternal education among participants was notably high. Over 60% of mothers across all diagnostic and sex subgroups held college degrees.

Similarly, more than 60% of families reported incomes surpassing the 2010 US median of USD 50,000. This trend of higher income was particularly evident among controls and non-regressive autism cases.

About 70% of both cases and controls were sourced from the IAN in the male subset. Around 70% of male patients identified as Non-Hispanic White (NHW), while 64% of controls did.

In contrast, female statistics showed that approximately 90% of cases came from IAN and were NHW. However, only 60% of female controls fit this demographic.

Regarding early dietary sweetener (DS_early) and aspartame (ASP_early) exposures among males, there was a conspicuous increase in exposure frequency as the severity of the diagnostic category grew, peaking with non-regressive autism cases.

Around 23.3% of males with non-regressive autism were exposed to ASP_early, and 22.1% to DS_early, compared to just 7.4% of controls. Such trends were absent in females.

Further, odds ratios (ORs) highlighted a relationship between DS_early exposure and diagnostic severity, especially in males.

Males with autism had tripled odds of DS_early exposure, particularly among non-regressive cases, while no such correlations were observed for females or ASD.

Similarly, ASP_early exposures rose with increasing diagnosis severity in males. The odds more than tripled for all autism cases and were even higher for non-regressive autism cases. Yet, as with DS_early, no significant links were observed between ASP_early exposure and total ASD in boys or any ASD-related diagnoses in girls.

The study also considered general non-nutritive sweetener (NNS) consumption. Although daily early-life exposures to aspartame showed higher odds ratios concerning the severity of diagnosis, these did not attain statistical significance.

This implies that only high daily dosages of either DS or aspartame may have associations with autism in boys, but lower doses do not.

Sensitivity analysis showed that NNS consumption habits among biological mothers of male offspring were consistent across various socioeconomic factors, such as income, education, and ethnicity.

Nonetheless, slightly higher consumption rates were seen in affluent households and among mothers with college degrees. About 28% of mothers reported consuming NNS equivalent to at least one tabletop packet daily during pregnancy, aligning with previous studies.

Conclusions

In the present study examining maternal intake of diet soda and aspartame during pregnancy or breastfeeding, researchers found that boys exposed early to these substances had an increased risk of autism.

However, this association was not observed in girls, who comprised only 17% of autism cases in this study.

The lack of association in girls might be due to insufficient sample size or differences in gender response. Prior research had noted neurological reactions in adults consuming aspartame and adverse outcomes in offspring from mothers who drank diet beverages.

Further research is essential, especially considering the widespread use of such products among pregnant women.