Our diets can affect our health, but despite extensive research, we still don’t have a great understanding of what diets are best for which people, and whether different diets can improve certain health conditions. Now, researchers have discovered that a molecule found in plants, a carotenoid known as zeaxanthin, can boost the immune system to help it fend off cancer. While more research will be needed to confirm these findings, the study suggested that zeaxanthin could work as a supplement that improves the efficacy of cancer immunotherapies. This work has been published in Cell Reports Medicine.
"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 co-corresponding study author Jing Chen, PhD, a Professor at the University of Chicago. "Our study shows that a simple dietary nutrient could complement and strengthen advanced cancer treatments like immunotherapy."
The Chen lab has been working for years to learn how nutrients can influence the immune system in various ways. They determined that zeaxanthin can enhance the function of an important immune cell type called CD8+ T cells. These cells can kill tumors and identify abnormal cells that should be destroyed, with a molecule known as the T-cell receptor (TCR).
This study revealed that when TCRs on CD8+ T cells interact with cancer cells, zeaxanthin makes the link stronger and more stable. This leads to bigger signals that activate more immune cells and molecules to eliminate cancer cells.
The investigators used a mouse model to show that zeaxanthin added to the diet can reduce tumor growth. When zeaxanthin was given along with immune checkpoint inhibitors, the antitumor effects of these drugs were more robust. These results were also replicated with T cells that had been engineered to identify certain cancer types like glioblastoma or multiple myeloma.
"Our data show that zeaxanthin improves both natural and engineered T-cell responses, which suggests high translational potential for patients undergoing immunotherapies," suggested Chen..
Since zeaxanthin is available over-the-counter as an inexpensive supplement for eye health, and can be found in vegetables like orange peppers, spinach, and kale, people can easily obtain it or add it to their diet. It has also been found to be safe. But the study authors are not yet recommending that people undergoing immunotherapies also use zeaxanthin, since these findings need to be explored and confirmed in clinical trials with cancer patients. But it highlights the importance of eating healthy foods and a balanced diet.
"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."
Sources: University of Chicago Medical Center, Cell Reports Medicine