Sweetener May Weaken Cancer Treatment, Study Finds

Sucralose, a widely used artificial sweetener found in diet sodas and sugar-free snacks, may reduce the effectiveness of cancer immunotherapy. New research from the University of Pittsburgh and UPMC Hillman Cancer Center suggests that even small amounts of this sugar substitute could negatively affect treatment outcomes in certain cancers.

The study involved patients with melanoma and non-small cell lung cancer. These are serious cancers often treated using immunotherapy. Researchers observed that people who regularly consumed sucralose had weaker responses to treatment and shorter survival compared to those who consumed little or none.

How Sucralose Affects the Body

To better understand the impact, researchers turned to mouse models. The findings revealed that sucralose alters the gut microbiome, the collection of bacteria that live in the digestive tract. This shift caused a reduction in arginine, an amino acid that plays a key role in immune cell function.

Immunotherapy relies on activating T cells to fight cancer. However, with reduced arginine levels, these immune cells could not function effectively. As a result, tumors grew larger and survival worsened in mice that received sucralose.

This effect was seen in models of both melanoma and adenocarcinoma. In these cases, sucralose weakened the impact of anti-PD1 therapy, an immune checkpoint inhibitor used in cancer treatment.

Is the Effect Reversible?

There is some good news. The researchers found that supplementing with either arginine or citrulline (an amino acid that the body converts into arginine) helped restore the immune response. Both supplements are commonly available and generally well tolerated, even among people taking multiple medications.

“This is promising because asking cancer patients to completely change their diets is often unrealistic,” said Dr. Abby Overacre, one of the study’s authors. “But a simple supplement might offer real benefits.”

How Much Is Too Much?

Surprisingly, the amount of sucralose linked to these effects was very small. Just 0.16 milligrams per kilogram of body weight per day was enough to be associated with poorer outcomes. For a person weighing 70 kilograms, that’s less than one packet of sweetener per day.

The study also analyzed dietary data from 132 patients who were receiving immunotherapy. Those who consumed sucralose regularly had worse responses to treatment across different cancer types, treatment stages, and therapeutic combinations.

“These findings point toward the possibility of using targeted supplements for patients who consume high levels of sucralose,” said Dr. Diwakar Davar, co-author and medical oncologist.

What Comes Next?

While reducing sucralose intake may help, it is not always easy. Sucralose is often present in foods and drinks without clear labeling. Many people may not even realize they are consuming it.

The researchers plan to conduct clinical trials to evaluate whether removing sucralose from the diet or adding supplements like arginine can improve outcomes for cancer patients. They also intend to study other artificial sweeteners, including aspartame, saccharin, xylitol, and stevia, to explore whether they cause similar effects.

Although more research is needed, the study highlights an important idea. Everyday dietary choices can interact with medical treatments in unexpected ways. For patients undergoing immunotherapy, paying attention to what’s in your food could make a real difference.