Stevia, a zero-calorie sugar substitute, combined with probiotics, yields a surprising and targeted cancer-killing effect. Credit: Shutterstock
Researchers at Hiroshima University have found that stevia, when fermented with specific bacteria from banana leaves, gains a remarkable ability to kill pancreatic cancer cells while leaving healthy kidney cells unharmed.
This transformation enhances the plant’s natural properties through microbial biotransformation, creating a potent compound called chlorogenic acid methyl ester (CAME). The fermented stevia extract showed significant cancer-fighting potential in lab tests and may represent a new direction in probiotic-based cancer therapies.
Stevia’s Surprising Anti-Cancer Potential
Stevia might offer more than just a no-calorie alternative to sugar. Scientists at Hiroshima University found that when stevia extract is fermented using bacteria sourced from banana leaves, it becomes capable of killing pancreatic cancer cells without damaging healthy kidney cells.
The results of their study were published in the International Journal of Molecular Sciences.
“Globally, the incidence and mortality rates of pancreatic cancer continue to rise, with a five-year survival rate of less than 10%,” said co-author Narandalai Danshiitsoodol, associate professor in Department of Probiotic Science for Preventive Medicine, Graduate School of Biomedical and Health Sciences.
“Pancreatic cancer is highly invasive and prone to metastasis, showing significant resistance to existing treatments, such as surgery, radiotherapy, and chemotherapy. As such, there is an urgent need to identify new and effective anticancer compounds, particularly those derived from medicinal plants.”
The overall mechanism for the induction of apoptosis in PANC-1 cells by stevia leaf extract fermented with Lactobacillus plantarum SN13T strain. Credit: Zhang Rentao/Hiroshima University
Fermentation Unlocks Bioactive Compounds
Earlier research had suggested that stevia leaf extract could help fight cancer, but pinpointing and isolating the specific active compounds has proven difficult. Danshiitsoodol explained that fermentation can alter the structure of stevia extract, leading to the creation of new bioactive metabolites. These are compounds that can influence biological systems.
“To enhance the pharmacological efficacy of natural plant extracts, microbial biotransformation has emerged as an effective strategy,” said corresponding author Masanori Sugiyama, professor in the Department of Probiotic Science for Preventive Medicine, Graduate School of Biomedical and Health Sciences.
Sugiyama’s lab has isolated and evaluated the health benefits of more than 1,300 lactic acid bacteria (LAB) strains from fruits, vegetables, flowers, and medicinal plants. “In this study, we aimed to compare LAB-fermented and non-fermented extracts to identify key compounds that enhance bioactivity, ultimately contributing to the efficacy of herbal medicine in cancer prevention and therapy.”
Fermented Stevia Extract Targets Cancer Cells
Specifically, the team fermented stevia leaf extract with plant-derived Lactobacillus plantarum SN13T strain (FSLE) and compared its effects on pancreatic cancer (PANC-1) cells in the lab, alongside non-cancerous human embryonic kidney cells HEK-293, to the effects of non-fermented stevia extract. The cells utilized in these experiments were acquired from established commercial cell lines.
“Our findings indicate that FSLE demonstrates significantly greater cytotoxicity than the non-fermented extract at equivalent concentrations, suggesting that the fermentation process enhances the bioactivity of the extract,” Sugiyama said. “Notably, FSLE exhibited lower toxicity toward the HEK-293 cells, with minimal inhibition observed even at the highest concentration tested.”
Discovery of a Powerful Cancer-Fighting Molecule
Additional analyses identified chlorogenic acid methyl ester (CAME) as the active anti-cancer compound. When fermented, the concentration of chlorogenic acid in the extract dropped six-fold, indicating a microbial transformation, according to Danshiitsoodol.
“This microbial transformation was likely due to specific enzymes in the bacteria strain used,” Danshiitsoodol said. “Our data demonstrate that CAME exhibits stronger toxicity to cells and pro-apoptotic effects — which encourage cell death — on PANC-1 cells compared to chlorogenic acid alone.”
Next, the researchers said they plan to study the effects in a mouse model to better understand the effectiveness of various dosages across a whole-body system.
“The present study has substantially enhanced our understanding of the mechanism of action of the Lactobacillus plantarum SN13T strain in the fermentation of herbal extracts, while also offering a valuable research perspective on the potential application of probiotics as natural anti-tumor agents,” Danshiitsoodol said.
Reference: “Stevia Leaf Extract Fermented with Plant-Derived Lactobacillus plantarum SN13T Displays Anticancer Activity to Pancreatic Cancer PANC-1 Cell Line” by Rentao Zhang, Narandalai Danshiitsoodol, Masafumi Noda, Sayaka Yonezawa, Keishi Kanno and Masanori Sugiyama, 27 April 2025, International Journal of Molecular Sciences.
DOI: 10.3390/ijms26094186
Other contributors include Rentao Zhang and Masafumi Noda, Department of Probiotic Science for Preventive Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University; and Sayaka Yonezawa and Keishi Kanno, Department of General Internal Medicine, Hiroshima University Hospital.