Zeaxanthin, Best Known For Eye Health, Boosts Cancer-Fighting Cells In Mouse Study
Scientists searching for nutrients that bolster the immune system have identified an unexpected candidate: zeaxanthin, a pigment found in corn, spinach, and egg yolks that is commonly marketed for eye health.
Researchers at the University of Chicago discovered that zeaxanthin enhanced the ability of CD8+ T cells to attack and destroy tumor cells in mice. When mice with melanoma tumors received daily oral doses of zeaxanthin, tumor growth slowed in mice compared to untreated animals. The compound also worked with checkpoint inhibitor drugs, a type of immunotherapy, to further suppress tumor growth.
The findings, published in Cell Reports Medicine, emerged from a systematic screen of hundreds of nutrients circulating in human blood. The research team co-cultured immune cells with tumor cells in the presence of various dietary compounds to identify which ones improved the immune system’s cancer-fighting capacity.
Structural Twins with Different Effects
Zeaxanthin and lutein are chemical cousins. Both belong to the carotenoid family, differ by just one double bond in their molecular structure, and concentrate in the human retina where they filter blue light. Both are sold as vision supplements, often combined in the same pill.
Yet only zeaxanthin enhanced immune function in the experiments.
When the scientists tested lutein alongside zeaxanthin, lutein failed to increase T cell activation or improve tumor control in mice. This specificity suggests that zeaxanthin’s effects depend on its precise molecular shape rather than general antioxidant properties shared by many carotenoids.
The research team tested several structurally similar compounds and found that only zeaxanthin and fucoxanthin, another carotenoid from seaweed, significantly boosted T cell activity. The symmetrical structure of zeaxanthin, with matching ring structures at both ends of its molecular chain, may be critical for its immune effects.
