Common sweetener now linked to impaired memory and learning

Two months on from it being declared safe by the FDA, aspartame is again making headlines for the wrong reasons, this time for its potential negative impact on learning and memory.

Researchers at Florida State University (FSU) College of Medicine have found that male mice consuming aspartame at significantly lower levels than deemed safe by the Food and Drug Administration (FDA) passed on spatial learning and memory deficits to their offspring.

These hereditary signs were absent from a control group not exposed to aspartame.

The findings follow on from a 2022 study by the researchers that linked aspartame consumption to inherited anxiety-like behavior that spanned two generations.

“There is some overlap in terms of learning, memory and anxiety, in the sense that often there is an emotional component to our learning,” said co-author Pradeep Bhide, from FSU’s Department of Biomedical Sciences. “When there’s an emotional impact, you remember better. But this is a quite distinct function and brain network.

“The second thing we noticed here, unlike the anxiety (research), this went only one generation,” he added. “It was not seen in the grandchildren, only in the children [of the male mice], which is another line of support that these kinds of transmissions occur due to epigenetic changes in the sperm.”

Over 16 weeks, one group of mice ingested water mixed with 7% of the FDA’s maximum intake of aspartame – equivalent to two 8-ounce (237-ml) diet sodas daily – and another was given a higher dose, 15%. The control, of course, consumed only water.

The mice were tested on different cognitive tasks in weeks four, eight and 12, with the final test requiring the animals to learn to find a “safe” escape box out of 40 choices in a circular space.

The aspartame-free control mice found the box fast; both the 7% and 15% aspartame group took much longer to learn the task at hand.

Then, when the males were bred with females who were not exposed to aspartame, both male and female offspring in the first generation has similar deficiencies in learning and memory.

“We’re seeing they use a different strategy, but they do find the escape box,” said co-author Deirdre McCarthy, from the Department of Biomedical Sciences and the Center for Brain Repair. “They compensate in some sort of way.”

“Again, they can function, but they need longer time, or may need extra help,” said Bhide.

The researchers hope to look into the aspartame-induced epigenetic changes in sperm. Interestingly, the learning and memory deficits were not passed on to a second generation of mice.

Earlier studies have linked aspartame to other health issues, including disruption to the gut microbiome, blood sugar regulation and weight gain.

In July, the cancer-research arm of the World Health Organization (WHO) officially named aspartame as possibly carcinogenic to humans, which the FDA challenged soon after.

Aspartame was first approved for use in tabletop sweeteners in 1981, diet sodas in 1983 and in other products in 1996. It's now used in more than 6,000 products across the globe, including in toothpaste and chewable vitamins.

The study was published in the journal Scientific Reports.

Source: Florida State University