Fermentation boosts stevia’s ability to target cancer cells while leaving healthy ones unharmed.
Hiroshima University researchers have found that fermented stevia extract may fight pancreatic cancer without harming healthy cells—potentially making it more than just a zero-calorie sugar substitute.
Pancreatic cancer shows significant resistance to existing treatments like surgery, chemotherapy, and radiation.
“Globally, the incidence and mortality rates of pancreatic cancer continue to rise, with a five-year survival rate of less than 10 percent,” study coauthor Narandalai Danshiitsoodol, associate professor at Hiroshima University, said in a press statement.
There’s a growing need to find new, effective cancer-fighting compounds—especially those that come from medicinal plants, said Danshiitsoodol.
Fermentation Unlocks Cancer-Fighting Power
The study, recently published in the International Journal of Molecular Sciences, found that when stevia is fermented with a probiotic, the resulting extract kills pancreatic cancer cells while sparing healthy kidney cells. The fermented extract inhibited cancer growth but did not harm normal cells.
The research team fermented stevia leaf extract using the probiotic Lactobacillus plantarum SN13T, a beneficial bacterium commonly found in fermented foods like sauerkraut, pickles, and kimchi. The researchers noted that fermenting the extract with bacteria can change its structure and produce beneficial compounds called bioactive metabolites.
“To enhance the pharmacological efficacy of natural plant extracts, microbial biotransformation has emerged as an effective strategy,” Masanori Sugiyama, a professor of microbiology and biotechnology and coauthor of the study, said in a press statement.
Sugiyama’s lab has studied more than 1,200 strains of bacteria from fruits, vegetables, flowers, and medicinal plants, evaluating their health benefits.
The results showed that the fermented stevia leaf extract (FSLE) was more effective at killing cancer cells than the nonfermented version.
Sugiyama said that FSLE was also less harmful to the HEK-293 cells, which are human kidney cells used in the study. Even at the highest dose tested, FSLE caused minimal damage to these cells.
This is important because conventional chemotherapy, such as cisplatin, can damage the kidneys—especially the left one, which is adjacent to the pancreas.
Key Anticancer Agent Identified
Further analysis identified a compound called chlorogenic acid methyl ester (CAME) as the key anticancer agent. Fermentation reduced the amount of chlorogenic acid—a precursor to CAME—in the extract by sixfold, a change caused by bacterial enzymes, corresponding to the production of CAME, according to Danshiitsoodol.
“This microbial transformation was likely due to specific enzymes in the bacteria strain used,” she said.
CAME was found to stop cancer cells from multiplying, trigger them to self-destruct, and change the expression of key genes so that cells are more likely to die.
The experiments were conducted on cancer cells grown in laboratory dishes—not in living organisms. The researchers plan to conduct tests in mice to better understand how different doses of the fermented extract affect the entire body.
They emphasized that their results help explain how probiotic bacteria can boost the anticancer effects of herbal medicines. Danshiitsoodol noted that the study significantly advances understanding of how the Lactobacillus plantarum SN13T strain works in fermenting herbal extracts, and it also offers insight into using probiotics as natural antitumor agents.
Stevia Safety and Benefits
Dr. Joseph Mercola, a board-certified family medicine physician not involved in the study, called the research “a powerful reminder” that plants such as stevia offer more than just sweetness—they may deliver compounds that support long-term health.
Mercola noted that stevia extract is a “far healthier” alternative to artificial sweeteners such as aspartame, sucralose, or saccharin.
“Unlike synthetic options that can disrupt gut bacteria or trigger metabolic changes, pure stevia extract—which has a glycemic index close to zero—has minimal to no impact on your blood sugar or insulin,” he said.
However, he cautioned that sweeteners blended with stevia—such as those containing dextrose or maltodextrin—can raise blood sugar if taken in large amounts.
