Researchers found that zeaxanthin, long associated with eye health, may also boost the body’s immune response against cancer.
In a recent study, scientists at the University of Chicago found that zeaxanthin, a carotenoid derived from plants and traditionally recognized for supporting eye health, may also enhance immune function by boosting the tumor-fighting abilities of certain immune cells. Published in Cell Reports Medicine, the research points to zeaxanthin’s promise as an accessible supplement that could improve the effectiveness of cancer immunotherapies.
“We were surprised to find that zeaxanthin, already known for its role in eye health, has a completely new function in boosting anti-tumor immunity,” said Jing Chen, PhD, Janet Davison Rowley Distinguished Service Professor of Medicine and senior author of the study. “Our study shows that a simple dietary nutrient could complement and strengthen advanced cancer treatments like immunotherapy.”
How does this nutrient work?
Chen’s laboratory has spent years investigating how nutrients shape immune function, and this study extends that effort. By screening an extensive library of blood nutrients, the team pinpointed zeaxanthin as a compound that directly boosts the activity of CD8+ T cells, the immune cells responsible for killing tumor cells. These T cells depend on a structure known as the T-cell receptor (TCR) to detect and eliminate abnormal cells.
The researchers discovered that zeaxanthin helps stabilize and reinforce the TCR complex on CD8+ T cells when they engage with cancer cells. This strengthening effect amplifies intracellular signaling, leading to greater T-cell activation, higher cytokine production, and improved tumor-killing performance.
Zeaxanthin improves immunotherapy effects
In mouse experiments, dietary zeaxanthin supplementation slowed the progression of tumors. Even more striking, when paired with immune checkpoint inhibitors—a widely used form of cancer immunotherapy—zeaxanthin markedly increased anti-tumor activity compared to immunotherapy on its own.
To extend the findings, the researchers tested human T cells engineered to recognize specific tumor antigens and found that zeaxanthin treatment improved these cells’ ability to kill melanoma, multiple myeloma, and glioblastoma cells in laboratory experiments.
“Our data show that zeaxanthin improves both natural and engineered T-cell responses, which suggests high translational potential for patients undergoing immunotherapies,” Chen said.
A safe and accessible candidate
Zeaxanthin is sold as an over-the-counter supplement for eye health, and is naturally found in vegetables like orange peppers, spinach, and kale. It’s inexpensive, widely available, well-tolerated and, most importantly, its safety profile is known – which means it can be safely tested as an adjunct to cancer therapies.
The study also reinforces the importance of a balanced diet. In their previous research, Chen’s group discovered that trans-vaccenic acid (TVA), a fatty acid derived from dairy and meat, also boosts T-cell activity – but through a different mechanism. Together, the findings suggest that nutrients from both plant and animal sources may provide complementary benefits to immune health.
Clinical applications of zeaxanthin
Although the results are promising, the researchers emphasize that the work is still at an early stage. Most of the findings come from laboratory experiments and animal studies. Thus, clinical trials will be needed to determine whether zeaxanthin supplements can improve outcomes for cancer patients.
“Our findings open a new field of nutritional immunology that looks at how specific dietary components interact with the immune system at the molecular level,” Chen said. “With more research, we may discover natural compounds that make today’s cancer therapies more effective and accessible.”
Reference: “Zeaxanthin augments CD8+ effector T cell function and immunotherapy efficacy” by Freya Q. Zhang, Jiacheng Li, Rukang Zhang, Jiayi Tu, Zhicheng Xie, Takemasa Tsuji, Hardik Shah, Matthew O. Ross, Ruitu Lyu, Junko Matsuzaki, Anna Tabor, Kelly Xue, Fatima Choudhry, Chunzhao Yin, Hamed R. Youshanlouei, Syed Shah, Michael W. Drazer, Yu-Ying He, B. Marc Bissonnette, Yuancheng Li, Hui Mao, Jun Huang, Lei Dong, Rui Su, Chuan He, Kunle Odunsi, Jing Chen and Hao Fan, 1 September 2025, Cell Reports Medicine.
DOI: 10.1016/j.xcrm.2025.102324
The research was supported by grants from the National Institutes of Health, the Ludwig Center at the University of Chicago, and the Harborview Foundation Gift Fund.
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