This Artificial Sweetener Has a Surprising Effect on the Immune System

A mouse study shows a unique benefit of Splenda.

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Artificial sweeteners get a bad reputation. To be fair, natural sweeteners do, too. But in the past few decades, researchers have put tremendous effort into studying the health effects, particularly the detrimental ones, of these sugar substitutes. This week, scientists report a surprising twist: One of the most popular and commonly used artificial sweeteners, sucralose, may benefit our immune systems.

A mouse study published today in the journal Nature depicts how high doses of sucralose impact the body. Of particular interest to the authors, sucralose had no observable changes — other than those made to the immune system. While this research is preliminary, it could lead to a supplementary treatment for those with autoimmune disorders.

Sucralose’s Potential Superpower

Sucralose — better known as Splenda — is an artificial sweetener that, according to the paper, is 600 times sweeter than sugar with none of the calories.

After performing various experiments in mice, the researchers observed that mice who consumed sucralose over 12 weeks had suppressed T cells, a type of white blood cell that makes up part of the immune system’s army.

What’s more, this change was temporary. “If we take away the sucralose, the immune response [goes] back to normal,” said co-author Fabio Zani, a postdoctoral training fellow at The Francis Crick Institute, at a press briefing.

“This article paves the way for future modulation of the immune system directly through alimentation,” writes Gaëtan Barbet, an immunology professor at Rutgers University, to Inverse. “There is still a long way to go for translating this research to humans, but it is definitely going in the right direction.” Barbet was not involved in the research.

The Food and Drug Administration (FDA) set the maximum acceptable daily intake of sucralose at 5 milligrams per kilogram of body weight. In Europe, the maximum is even higher at 15 mg per kg of body weight. Most people don’t even approach the upper limit. That kind of sucralose intake can only come from 10 cans of soda in one day or 30 cups of Splenda-sweetened coffee, according to supervising author Karen Vousden, a cancer researcher and lab lead at The Francis Crick Institute.

Mice received the equivalent amounts, according to the FDA and European authorities, at 0.17 milligrams per milliliter^-1 and 0.72 mg per ml^-1 in their drinking water.

On the other end of the spectrum, Vousden underscores that the amounts of sucralose typically consumed are too low to meaningfully impact T cells. If you enjoy Splenda in every cup of tea, that’s not going to change your immune response.

The team stressed that since this is a mouse study, it’s no indication of what high doses of sucralose in humans may do. “As of yet, we do not know whether or not we would be able to see similar effects in humans,” co-author Julianna Blagih, a metabolism researcher at The Francis Crick Institute, said at the briefing.

It is, however, worth finding out.

When The Immune System Needs Suppressing

It may seem alarming that fake sugar might actually suppress the cells that help fight off infection, but this finding indicates that sucralose may be helpful to humans. What’s more, Vousden and co-authors Fabio Zani and Julianna Blagih underscored that the amounts in which people consume sucralose are low enough to not meaningfully impact their immune systems. Autoimmune disorders, like type 1 diabetes, occur when the immune system attacks your own body.

Another novel aspect of this finding is how isolated the effect is. Sucralose’s only observable effect on the mice was on their T cells. This means that it could become a treatment with minimal to no unpleasant side effects.

Sweet somethings

This paper is the product of more than five years of research. Blagih says she remembers doing the team’s first colitis model at the end of 2018.

Most researchers agree that this finding is preliminary and needs additional data, including future studies, to support it. Shin-Heng Chiou, an immunology professor at Rutgers University who was not involved with the research, writes to Inverse that he notices the “lack of mechanism of action that could explain how sucralose inhibits T cell function at high dose.”

Aware of this gap, Zani says that the missing biological mechanism merits further research.

“We don't have the full picture,” Zani said. There’s an inkling of how sucralose bamboozles a T cell’s membrane, impairing the cell’s activation, but still no evidence for the biological mechanism at work. “We are looking forward to [doing] more studies to try to figure it out.”

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