In patients with melanoma or non-small cell lung cancer, consuming high levels of the artificial sweetener sucralose contributes to diminished responses to immunotherapy and poorer survival, researchers reported in Cancer Discovery.

When the researchers had 132 patients with advanced melanoma or non-small cell lung cancer answer detailed diet history questionnaires, they found that high consumption of sucralose was linked with lower effectiveness of immunotherapies across a range of cancer types, stages and treatment methods.

In experiments with mice, the researchers found that sucralose shifts the composition of microbes in the intestines, increasing bacterial species that degrade arginine, an amino acid that is essential for key immune cells called T cells.

“When arginine levels were depleted due to sucralose-driven shifts in the microbiome, T cells couldn’t function properly,” study leader Abby Overacre of the University of Pittsburgh said in a statement. “As a result, immunotherapy wasn’t as effective in mice that were fed sucralose.”

Laying the groundwork for a solution to the problem, the same researchers also found in the mice that supplements that boosted levels of arginine mitigated the negative effects of sucralose on immunotherapy, an approach they now hope to test in humans.

“It’s easy to say, ‘Stop drinking diet soda,’ but when patients are being treated for cancer, they are already dealing with enough, so asking them to drastically alter their diet may not be realistic,” Overacre said.

“That’s why it’s so exciting that arginine supplementation could be a simple approach to counteract the negative effects of sucralose on immunotherapy.” REUTERS

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