In a recent study, scientists from the University of Chicago discovered that zeaxanthin, a carotenoid found in plants that is recognized for its role in protecting vision, may also strengthen immune cells' ability to fight cancer. The findings, published in Cell Reports Medicine, suggest that zeaxanthin could be a readily available supplement to boost the effectiveness of cancer immunotherapies.
Cell Reports Medicine"We were astonished to discover that zeaxanthin, which is already known for supporting eye health, has a novel function in enhancing anti-tumor immunity," said Jing Chen, Ph.D., Janet Davison Rowley Distinguished Service Professor of Medicine and senior author of the study. "Our research indicates that this dietary nutrient could enhance advanced cancer treatments like immunotherapy."
The study expands on previous work by Chen's lab to understand how nutrients affect the immune system. By analyzing a comprehensive blood nutrient library, the team identified zeaxanthin as a compound that enhances CD8+ T cells' activity—a vital type of immune cell that eliminates tumor cells through the T-cell receptor (TCR) mechanism.
The researchers found that zeaxanthin stabilizes and strengthens TCR complex formation on CD8+ T cells when interacting with cancer cells. This leads to stronger intracellular signaling, enhancing T-cell activation, cytokine production, and their ability to destroy tumors.
Mouse models showed that dietary supplementation with zeaxanthin slowed tumor growth. Moreover, combining it with immune checkpoint inhibitors—a type of immunotherapy—significantly improved the anti-tumor effects compared to using immunotherapy alone.
The researchers also tested human T cells genetically engineered to recognize specific tumor antigens and found that treatment with zeaxanthin improved these cells' ability to destroy melanoma, multiple myeloma, and glioblastoma cells in lab experiments.
"Our data shows that zeaxanthin enhances both natural and engineered T-cell responses, suggesting a strong potential for patients undergoing immunotherapies," Chen said.
Zeaxanthin is sold as an over-the-counter supplement to promote eye health and is naturally found in vegetables like orange peppers, spinach, and kale. It's affordable, widely available, well-tolerated, and has a known safety profile, making it suitable for testing alongside cancer treatments.
The study underscores the benefits of a balanced diet. In earlier research, Chen's team discovered that trans-vaccenic acid (TVA), a fatty acid from dairy and meat, also boosts T-cell activity through different mechanisms, suggesting that both plant and animal nutrients can enhance immune health.
While the results are promising, the researchers emphasize that more work is needed. Most findings come from lab experiments and animal studies, so clinical trials will be required to determine if zeaxanthin supplements improve outcomes for cancer patients.
"Our study opens a new field in nutritional immunology, exploring how specific dietary components interact with immune systems at the molecular level," Chen said. "With more research, we may find natural compounds that make today's cancer therapies more effective and accessible."