A preservative in processed foods can hold one of the clues to the rising rates of autism in the United States, according to a laboratory-based study by University of Central Florida researchers.
Scientists exposed human neural stem cells to high levels of the food preservative propionic acid or PPA and found that it reduced the development of neurons. The preservative is found in packaged and processed foods, such as baked goods and cheese.
The findings could mean that consuming too many foods that contain PPA during pregnancy can affect the development of the brain of the fetus or newborn and increase the risk of autism, researchers said.
The study doesn’t draw a cause-and-effect conclusion about PPA and autism. And because it was done in the lab, it’s too soon to tell what the findings mean for humans. But researchers say it’s another reminder about the importance of eating homemade, healthy foods during pregnancy.
“The ultimate goal of this study is really to prevent autism from happening,” said Dr. Saleh Naser, lead researcher and professor of medicine at the UCF College of Medicine. “What we are saying is that pregnant women should be careful about what they eat. Food containing PPA should avoided during pregnancy.”
Nearly one in 59 children in the United States is diagnosed with autism spectrum disorder, according to the latest report from Centers for Disease Control and Prevention. Two decades earlier, the odds of diagnosis were one in 150.
It’s still not clear what causes autism. It’s thought that the disorder results from culmination of several factors, including genetic predisposition, maternal immune system abnormalities in early pregnancy and environmental triggers.
“There’s a strong link that the environment can have an influence on autism, because one of the things we know is that the rate of autism has increased greatly in the past decades, and it’s not explained by genetic factors,” said Dr. Cheryl Rosenfeld, a professor at University of Missouri at the Bond Life Science Center, who was not involved in Naser’s study. “We’ve changed how we store our food and we eat much more processed food. Let’s go back to the way we had home-cooked meals” and use glass containers instead of plastic, she said.
Naser and his team decided to focus on PPA to fill in the gaps left by previous studies. One study has shown that injecting rats’ brains with PPA led to autistic-like behavior. Other studies have suggested that the type of neural cells in autistic brains are different from normal brains.
But it hasn’t been clear how, when and why the neural changes occur.
UCF researchers say they’re the first to discover the molecular effect of elevated levels of PPA on neural stem cell development and the potential link to autism.
The 18-month study, funded by UCF, was published in the Scientific Reports, a Nature journal.
Naser’s research showed that when human neural stem cells were exposed to excessive levels of PPA, they shifted to overproduction of glial cells and a reduction of the number of neurons.
Glial cells don’t participate in electrical signaling in the brain. Their role is supportive. But too many glial cells can disrupt the connectivity between neurons. They can also cause inflammation in the brain.
Moreover, when researchers looked at the neurons, they found that most of them were unhealthy.
Reduced neurons and damaged pathways can hamper the brain’s ability communicate and result in repetitive behavior, mobility issues and the inability to interact with others, which are some of the hallmarks of autism, researchers said.
“The study warrants follow-ups but in and of itself, to me, it’s just a tiny piece of a potential puzzle,” said Rosenfeld of the University of Missouri. “It’s not something that readers should be alarmed on.”
She also said it’s not clear whether real-life doses of PPA can be as high as what was used in the lab.
Naser and his team are planning to next run the experiment in mice.
“My message has been firm to all women during pregnancy," he said. "Eating healthy is a must and not an option.”