Study Links Sucralose Consumption to Reduced Immunotherapy Effectiveness in Small Patient Cohort

A study published in Cancer Discovery found that patients who reported high consumption of the artificial sweetener sucralose had weaker responses to anti‑PD‑1 immunotherapy and poorer survival than patients who reported low consumption.

The observational analysis included 132 patients with melanoma or non‑small cell lung cancer who were receiving anti‑PD‑1 therapy alone or in combination with chemotherapy. Researchers at the University of Pittsburgh and UPMC Hillman Cancer Center gathered dietary information through questionnaires and compared clinical outcomes across reported levels of sucralose intake.

Investigators reported that higher reported sucralose intake was linked with a “worse response” to immunotherapy and reduced survival, a pattern that held across cancer types, stages and treatment modalities, according to senior author Diwakar Davar, an associate professor of medicine at Pitt and a medical oncologist at UPMC Hillman Cancer Center.

The research team complemented the human observations with laboratory experiments in mice. In those models, sucralose altered the gut microbiome in ways that reduced levels of the amino acid arginine, which the authors said is essential for T‑cell function. When arginine levels were depleted, T cells were less able to mount an effective response and immunotherapy was less effective in mice fed sucralose.

Lead author Abby Overacre, an assistant professor in Pitt’s Department of Immunology, said arginine supplementation in the mouse experiments counteracted the negative effects of sucralose and boosted the effectiveness of checkpoint blockade therapy. The authors said these findings suggest a possible approach of targeted nutrient supplementation for patients who consume high levels of sucralose.

The paper and its authors emphasize limits to the current evidence. The human component was an observational study with a modest sample size that relied on self‑reported dietary data, which can be affected by misreporting and recall bias. The mechanistic findings derive primarily from animal experiments, which cannot be directly extrapolated to human patients. The Calorie Control Council, responding to the findings, noted that regulatory authorities including the U.S. Food and Drug Administration have repeatedly confirmed sucralose’s safety and urged that treatment guidance come from patients’ healthcare teams.

The study was supported by the National Institutes of Health, the Damon Runyon Cancer Research Foundation and Gateway for Cancer Research. The authors said they plan to launch a clinical trial to test whether arginine supplementation can offset any negative effects of sucralose on immunotherapy in humans and will investigate the potential impact of other sugar substitutes.

Researchers and patient advocates said the findings do not constitute clinical guidance and that clinicians should counsel individual patients. The study’s combination of human observational data and laboratory work provides a basis for further clinical investigation into how diet and the gut microbiome may influence responses to cancer immunotherapy.