In a study published in the journal Proceedings of the National Academy of Sciences, American scientists from Florida State University have found a link in mice between aspartame, a sweetener found in thousands of diet foods and drinks, and anxiety-like behavior that would remain present in the next two generations.
Aspartame is an artificial sweetener that has been widely used in place of conventional sugar in low-calorie foods and beverages since it was approved by the U.S. Food and Drug Administration in 1981. Since then, aspartame has been regularly criticized for its potential adverse effects and its effects on the nervous system. When ingested, aspartame breaks down into two amino acids, aspartic acid and phenylalanine, the latter being a compound that allows the production of neurotransmitters, it can act on the nervous system. The scientists sought to know how mice would behave when ingesting aspartame, but also what effect it would have on the expression of their genes.
This study, which follows a study on the transgenerational effects of nicotine on mice, consisted of giving mice drinking water containing aspartame for twelve weeks at nearly 15% of the maximum daily dose approved for humans by the FDA. This dose is equivalent to about six to eight cans of diet soda per day, and the U.S. government’s health policy states that aspartame is safe when consumed within the maximum daily intake limit of 50 mg/kg.
Exposure of mice to the sweetener resulted in anxiety-like behavior and disruption of neurotransmitter signalling. RNA sequencing also revealed epigenetic, and therefore temporary, changes in the expression of genes that regulate the arousal/inhibition balance in the amygdala, the brain region that regulates fear and anxiety.
The anxiety disorder in the mice was alleviated by administering diazepam, a drug used to treat generalized anxiety disorder. The researchers were also surprised to find that anxiety, its response to diazepam and changes in gene expression in the amygdala were not limited to aspartame-exposed individuals, but also appeared in two generations descended from aspartame-exposed males. The scientists conclude that the human population exposed to the potential mental health effects of aspartame may be larger than currently predicted, which includes only aspartame-using individuals. Future studies plan to evaluate the effects of aspartame on memory, and further research should identify the molecular mechanisms that influence the intergenerational transmission of aspartame’s effect.