A Common Artificial Sweetener Is Linked to Anxiety-like Behavior

Researchers at the Florida State University College of Medicine have found a link between aspartame and behavior similar to anxiety. Artificial sweetener is found in almost 5,000 low-calorie foods and drinks.

Key takeaways:
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    A recent study at the Florida State University College of Medicine found a link between aspartame and anxiety-like behavior.
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    Aspartame, a popular artificial sweetener, is found in thousands of diet foods and drinks.
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    Anxiety-like behavior brought on by aspartame exposure can be potentially passed down to further generations, though the effects may not be as severe.

What do many diet soft drinks and sugar-free foods have in common? It’s called aspartame, and this artificial sweetener is found in thousands of diet foods and drinks. But did you know aspartame may be linked to anxiety?

A recent study at the Florida State University College of Medicine found a link between the artificial sweetener aspartame and anxiety-like behavior in mice.

The peer-reviewed study, published earlier this month in the Proceedings of the National Academy of Sciences, found that even aspartame that adheres to the FDA guidelines can cause anxiety.

The researchers found that when aspartame is eaten, it breaks down into aspartic acid, phenylalanine, and methanol. All three of these chemicals can have strong effects on the central nervous system.

The study, led by doctoral candidate Sara Jones, placed aspartame in the mice’s drinking water at a level that was about 15% of the FDA-approved maximum daily intake for humans.

For reference, the dose is about the same as eight 8-ounce cans of diet soda a day for humans. The study continued for 12 weeks, spanning across four years.

Over time, the researchers noticed elevated anxiety levels in the mice. They also noticed that the mice’s gene cells had changed. The mice's amygdala's, a part of the brain that controls anxiety and fear responses, went off more often than usual after they were given aspartame. This fact may explain the increased anxiety in the mice.

"It was such a robust anxiety-like trait that I don't think any of us were anticipating we would see," Jones said. "It was completely unexpected. Usually you see subtle changes."

Even more surprising was the fact that the offspring of the males who had been exposed to aspartame also had higher levels of anxiety. This genetic testing was proof that the mice’s behavior could be passed down to later generations, even if the offspring weren’t exposed to aspartame.

However, the genetic testing also showed that the changes in the amygdala caused by aspartame were passed down from the mice that were given the sweetener to their offspring, but not to the generation after that.

Pradeep Bhide, who holds the Jim and Betty Ann Rodgers Eminent Scholar Chair of Developmental Neuroscience in the Department of Biomedical Sciences, explained:

What this study is showing is we need to look back at the environmental factors, because what we see today is not only what’s happening today, but what happened two generations ago and maybe even longer.

Diazepam, also known as Valium, was given to the aspartame-exposed mice to help calm their anxiety.

A key finding in the study was how diazepam affected the aspartame-exposed mice in relation to their offspring.

When the mice's offspring were given diazepam, it helped them feel much less anxious than when aspartame was given to the aspartame-exposed mice. This suggests that the sweetener's effects lessen over generations.

Aspartame is a sugar substitute that has been used in the United States since the early 1980s and is sold under brand names like NutraSweet® and Equal®.

Aspartame is used as a tabletop sweetener, in prepared foods and beverages, and in low-heat recipes (since heat breaks down aspartame). It is also used in some medicines to add flavor.

Studies have found links between aspartame and diseases like Alzheimer's, Parkinson's, multiple sclerosis, and brain tumors.

Scientists will continue to study the artificial sweeteners' possible effects on overall health.


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