Doctors have hit back against a controversial study that linked diet soda to autism.
Research by the University of Texas (UT) found boys diagnosed with autism were three times as likely to have mothers who drank diet soda daily while pregnant or breastfeeding.
They theorized that aspartame, the popular sugar substitute found in Diet Coke, may release toxins that cause oxidative stress in cells and tissues — a process linked to autism.
Researchers not involved with the study claimed it is ‘irresponsible’ to suggest a relationship between aspartame and autism without more research to back up the claim.
Dr Sharon Parten Fowler, lead study author and associate professor at the University of Texas San Antonio, said: ‘These associations still need to be explored in future large-scale, prospective studies, with measurement of maternal diet, as well as other maternal and paternal risk factors.’
‘Nonetheless, our study raises a warning flag – following a long line of warning flags from other studies – about the possible impact of mothers’ use of diet products during pregnancy on the health of their offspring.’
‘There appears to be a smoking gun here. And where there is a smoking gun, it needs to be investigated.’
Research from the University of Texas (UT) found that boys diagnosed with autism were more than three times as likely as non-autistic boys to have mothers who drank diet soda daily while pregnant or breastfeeding
The above products, as well as Weight Watchers yogurts and Conagra’s Mrs Butterworth’s syrups, all contain aspartame
But Dr Deirdre Tobias, a nutritionist at Harvard University who was not involved in the research, told DailyMail.com it was ‘shocking that the authors would feel confident enough in this design to draw those conclusions.’
Dr Rachel Moseley, principal academic in psychology at Bournemouth University in the UK, told DailyMail.com: ‘It would be highly premature and irresponsible to suggest a relationship between aspartame and autism based on this study. As every scientist knows, correlation between two things does not mean that the one causes the other.’
Dr Tobias said the study was ‘extremely flawed’ because the data was collected retrospectively and based on the mother’s memory of how much aspartame they consumed.
Dr Moseley added that the sample size is small and was recruited from a panel of parents with an autistic child.
‘Since autism has a large genetic component, having one autistic child is already associated with a higher risk of having another autistic child,’ she said.
‘Moreover, the authors did not rigorously confirm whether either or both of the parents were themselves autistic.’
In the study, the diets of mothers of 235 children with autism spectrum disorder were compared to a control group of mothers of 121 children who didn’t have autism.
The mothers completed questionnaires that asked: ‘While you were pregnant or breastfeeding your child, how often did you drink diet drinks containing artificial sweeteners?’
Diet Coke, Diet Dr Pepper, Diet Sprite, Crystal Light, sugar-free Kool-Aid, and Slim-Fast were suggested as prompts.
Each mother was also asked: ‘While you were pregnant or breastfeeding your child, how many little packets of low-calorie sweeteners (such as Sweet ‘N Low, Equal or Splenda) did you use in your coffee, tea, or other foods and beverages?’
Intake of the three leading sweeteners — Equal/Nutrasweet (blue), Splenda (yellow), and Sweet’N Low (pink) — was recorded.
The researchers found that males diagnosed with autism disorder were between 3.1 and 3.5 times more likely to have mothers who reported an aspartame intake equivalent to one or more diet sodas a day during pregnancy or breastfeeding, compared with male controls.
The association was greatest among males with non-regressive autism — where the condition is apparent before 18 months, also known as early onset.
The study did not find a statistically significant trend in autistic girls.
Conditions such as obesity and diabetes in mothers are associated with an increased risk of autism in children and may also influence a decision to use diet products.
The researchers did not collect data on these risk factors, nor smoking, drinking, birth weight, prematurity, or the age of the parents. They did have data for household income, educational attainment, and ethnicity, which they adjusted for in the results.
Dr Tobias added that the three artificial sweeteners they examined are ‘completely different compounds, metabolized very differently in humans, and have been extensively evaluated for their safety.
‘Thus, the fact that the signal for aspartame was essentially the same as the other chemicals further points to the bias in this study, perhaps due to errors in the mothers’ recall or other factors related to women who chose diet sodas.
‘It is extremely unlikely that any association they are observing has anything to do with the chemical aspartame itself.’
The study was published in the journal Nutrients.
During pregnancy, aspartame can cross the placenta and accumulate in fetal tissue.
The substance can also cross into breastmilk, but other studies have suggested the mother’s body rapidly breaks it down.
Autism affects one in 36 children, meaning that more than 90,000 children are born annually with the developmental disorder in the US.
It is characterized by problems with social communication and interaction, difficulty expressing oneself and repetitive behaviors and interests.
Autism is a lightning rod issue and often comes up in antivaxxer messaging.
In a recent poll, one-quarter of American adults said they believed the measles, mumps and rubella (MMR) vaccine causes autism – a widely studied and discredited claim that emerged in the 1990s.
Claims that shots can lead to autism have been peddled by anti-vaxxers for almost 25 years, but the link has been repeatedly disproven.
The disgraced British physician Andrew Wakefield made the claim in a now-retracted 1998 Lancet study.
Dr Richard Horton, editor of The Lancet, publicly described the research as ‘fundamentally flawed’ in 2004 – nine years after it was published.
Dr Horton alleged that Andrew Wakefield, the gastroenterologist behind the paper, was paid by a group pursuing lawsuits against vaccine manufacturers.
The prestigious medical journal finally retracted the paper in 2010.
Just three months after his paper was pulled, Wakefield was banned from practicing medicine in Britain by the General Medical Council.
In 2011, the British Medical Journal conducted a damning probe into the findings of Wakefield’s original study.
Its investigation found only two of the 12 children included developed autistic symptoms after being vaccinated – as opposed to the eight Wakefield claimed.
Since then, studies involving millions of children have failed to find a link between the MMR vaccine and the neurodevelopmental disorder.
