Researchers at the University of Chicago have discovered a surprising new role for zeaxanthin, a plant-based compound best known for supporting eye health. According to the survey results published in cell report medicinethis common carotenoid may also help the immune system fight cancer by increasing the activity of important immune cells. This finding indicates that zeaxanthin is a simple and widely available supplement that has the potential to improve the efficacy of cancer immunotherapy.
“We were surprised to discover that zeaxanthin, which is already known for its role in eye health, has an entirely new function in enhancing antitumor immunity,” said the study’s lead author, Dr. Jing Chen, the Janet Davison Lowry Distinguished Professor of Medicine. “Our study shows that simple dietary nutrients have the potential to complement and enhance advanced cancer treatments like immunotherapy.”
How zeaxanthin activates cancer-fighting T cells
The study builds on years of research in Chen’s lab studying how nutrients shape immune responses. By analyzing a large library of nutrients present in the blood, the research team identified zeaxanthin as a compound that directly enhances the performance of CD8+ T cells. These immune cells play a central role in identifying and destroying cancer cells.
CD8+ T cells rely on a structure called the T cell receptor (TCR) to detect abnormal cells. Researchers found that zeaxanthin helps stabilize the formation of this receptor complex when T cells encounter cancer. This enhances internal signaling, increases T cell activation, stimulates cytokine production, and improves the cells’ ability to kill tumors.
Boosting the power of immunotherapy
In a mouse study, adding zeaxanthin to the diet slowed tumor growth. This effect was even more pronounced when combined with immune checkpoint inhibitors, a type of immunotherapy that has revolutionized cancer treatment in recent years. The combination produced stronger antitumor responses than immunotherapy alone.
The researchers also tested human T cells that had been engineered to target specific cancer markers. In laboratory experiments, zeaxanthin enhanced the ability of these cells to destroy melanoma, multiple myeloma, and glioblastoma cells.
“Our data show that zeaxanthin improves both natural and engineered T cell responses, suggesting that this has high translational potential for patients receiving immunotherapy,” Chen said.
Safe, accessible nutrients with a wide range of potential
Zeaxanthin is already widely used as an over-the-counter supplement for eye health. It is found naturally in foods such as orange peppers, spinach, and kale. Because it is cheap, readily available, and well-tolerated, researchers believe it can be quickly tested as a complementary approach to cancer treatment.
The findings also highlight the broader importance of diet in immune health. In previous research, Chen’s team identified transvaccenic acid (TVA), a fatty acid found in dairy products and meat, as another compound that enhances T cell function through a different pathway. Taken together, these findings suggest that nutrients from both plant and animal sources may function complementarily to support the immune system.
Future developments of zeaxanthin in cancer treatment
Although the results are promising, the researchers stress that the study is still in its early stages. Most of the evidence to date comes from laboratory experiments and animal models. Clinical trials will be needed to determine whether zeaxanthin can improve outcomes for cancer patients.
“Our findings open up a new field of nutritional immunology that examines how specific dietary components interact with the immune system at the molecular level,” Chen said. “Further research may lead to the discovery of natural compounds that make today’s cancer treatments more effective and accessible.”
The study, “Zeaxanthin enhances CD8+ effector T cell function and immunotherapy efficacy,” was supported by grants from the National Institutes of Health, the University of Chicago Ludwig Center, and the Harborview Foundation Gift Fund.
Other authors include Freya Zhang, Jiacheng Li, Rukang Zhang, Jiayi Tu, Zhicheng Xie, Takemasa Tsuji, Hardik Shah, Matthew Ross, Ruitu Lyu, Junkomatsuzaki, Anna Tabor, Kelly Xue, Chunzhao ying, Hamed R. Youshanlouei, Syed Shah, Michael W. Drazer, Yu-Ying He, Marc Bissonnette, Jun Huang, Chuan He, Kunle Odunsi, and Hao Fan of the University of Chicago. Fatima Chaudhry of DePaul University in Chicago; Yuancheng Li and Hui Mao of Emory University School of Medicine in Atlanta; Lei Dong, University of Texas Southwestern Medical Center, Dallas; and Rui Su of the Beckman Institute at City of Hope in Duarte, California.
