Doctors have pushed back against a controversial study that linked diet soda to autism.
Research from the University of Texas (UT) found that boys diagnosed with autism were three times more likely than 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.
But Dr. Deirdre Tobias, a nutritionist at Harvard University who was not involved in the study, told DailyMail.com that it was “shocking that the authors would have enough confidence in this design to draw those conclusions.”
Dr. Rachel Moseley, chief scientist in psychology at Bournemouth University in Britain, told DailyMail.com: ‘It would be very premature and irresponsible to suggest a link between aspartame and autism on the basis of this research. As every scientist knows, correlation between two things does not mean that one causes the other.”
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 Mrs. Butterworth’s Conagra syrups, all contain aspartame
Dr. Tobias said the study was “extremely flawed” because the data was collected retrospectively and was based on mothers’ recollection of the amount of 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.
‘Additionally, the authors did not rigorously confirm whether one or both parents were themselves autistic.’
The study compared the diets of mothers of 235 children with an autism spectrum disorder with a control group of mothers of 121 children who did not have autism.
The mothers completed questionnaires that asked, “While you were pregnant or breastfeeding your child, how often did you drink diet drinks with artificial sweeteners?”
Diet Coke, Diet Dr Pepper, Diet Sprite, Crystal Light, sugar-free Kool-Aid and Slim-Fast were suggested as clues.
Each mother was also asked, “How many packets of low-calorie sweeteners (such as Sweet ‘N Low, Equal, or Splenda) did you use in your coffee, tea, or other foods while you were pregnant or breastfeeding your child?” drinks?’
Intake of the three main sweeteners – Equal/Nutrasweet (blue), Splenda (yellow) and Sweet’N Low (pink) – was recorded.
The researchers found that men diagnosed with autism were between 3.1 and 3.5 times more likely to be mothers who reported an aspartame intake equivalent to one or more diet sodas per day during pregnancy or lactation, compared with male control subjects.
The association was greatest among men with non-regressive autism – where the condition becomes visible before 18 months, also known as early onset.
The study found no statistically significant trend in autistic girls.
Conditions such as maternal obesity and diabetes are associated with an increased risk of autism in children and may also influence the decision to use diet products.
The researchers did not collect data on these risk factors, nor on smoking, drinking, birth weight, premature birth or the age of the parents. They did have data on family income, education level and ethnicity, which they corrected 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.”
‘So the fact that the signal for aspartame was essentially the same as for the other chemicals further points to the bias in this study, perhaps due to errors in the mothers’ memory or other factors associated with women taking light chose soft drinks.
‘It is extremely unlikely that the association they observe has anything to do with the chemical aspartame itself.’
The research was published in the journal Nutrients.
During pregnancy, aspartame can cross the placenta and accumulate in fetal tissue.
The substance can also pass into breast milk, but… other studies have suggested that the mother’s body breaks it down quickly.
Autism affects one in 36 children, meaning more than 90,000 children are born with the developmental disorder in the U.S. every year.
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 is often discussed in anti-vaxxer posts.
In a recent poll, a quarter of American adults said they believed the measles, mumps and rubella (MMR) vaccine causes autism – a much-studied and discredited claim that emerged in the 1990s.
Claims that vaccinations can lead to autism have been peddled by anti-vaxxers for nearly 25 years, but the link has been repeatedly debunked.
Disgraced British doctor Andrew Wakefield made this claim in a now retracted 1998 Lancet study.
Dr. Richard Horton, editor of The Lancet, publicly described the study 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 that filed lawsuits against vaccine manufacturers.
The prestigious medical journal eventually retracted the article in 2010.
Just three months after his papers were withdrawn, Wakefield was banned from practicing medicine in Britain by the General Medical Council.
In 2011, the British Medical Journal conducted a scathing investigation into the findings of Wakefield’s original study.
The study found that only two out of 12 children developed autistic symptoms after being vaccinated – unlike 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.