A common plant compound best known for protecting vision may also help the immune system fight cancer, according to new research from the University of Chicago Medical Center.
Scientists found that zeaxanthin, a carotenoid found in foods like spinach, kale and orange peppers, enhances the activity of CD8+ T cells, immune cells responsible for killing abnormal or cancerous cells. In lab and animal studies, zeaxanthin strengthened T-cell receptors, triggering more robust activation, cytokine release and tumor-killing ability.
When combined with immune checkpoint inhibitors, a form of cancer immunotherapy, dietary zeaxanthin slowed tumor growth in mice more effectively than immunotherapy alone. Researchers also saw benefits in human T cells engineered to target melanoma, multiple myeloma and glioblastoma cells in the lab.
“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 show that a simple dietary nutrient could complement and strengthen advanced cancer treatments like immunotherapy.”
Because zeaxanthin is already sold as an over-the-counter supplement for eye health and is widely consumed in vegetables, researchers say it is a safe candidate to test alongside cancer therapies. Still, most of the work so far has been conducted in animal models and laboratory settings. Clinical trials will be needed to determine whether the benefits translate to cancer patients.
The findings, published in Cell Reports Medicine, add to a growing field of “nutritional immunology,” which explores how specific dietary components interact with the immune system at a molecular level.
The research was supported by the National Institutes of Health, the Ludwig Center at the University of Chicago and the Harborview Foundation Gift Fund.