Zeaxanthin is one of two carotenoids in the retina of the human eye where it plays a role in the central macula.
Zeaxanthin is a yellow phytonutrient pigment located in many fruits and vegetables such as lettuce, broccoli, goji berry, kale, turnip greens, collard greens, kiwifruit, and Brussel sprouts. It is thought that deficient concentrations of plasma zeaxanthin in the human body are related to the development age-related macular degeneration (AMD).
Scientists have discovered that dietary zeaxanthin (carotenoid) was an independent predictor of resistance to neovascular age-related macular degeneration (AMD). In addition to protection from AMD, zeaxanthin appears to provide protection against cartilage defects when taken in conjunction with lutein.
In healthy, mature patients, reduced plasma concentrations of zeaxanthin are associated with impaired fasting glucose and type 2 diabetes. However, the primary benefits of zeaxanthin supplementation are visual. The causal relation between plasma carotenoids, including zeaxanthin, and age-related macular degeneration is well established.
As the human body ages, certain body parts and physiological processes break down and begin to fail. The quality of our eyesight is often one of the biological systems that breaks down due to age and disease-related structural changes in the retinal pigment epithelium. The eye is a biologically demanding organ as it requires an immense amount of oxygen to work correctly, and the lifelong exposure to light, coupled with the presence of polyunsaturated fatty acids, can lead to photo-oxidative damage. That's why nutrients that play a role in eye health like the antioxidant retinal pigments - zeaxanthin and lutein - which are supposed to protect the eye from oxidative damage, as well as provide a filter for light, are so important. Over a lifetime, the constant oxidative stress takes a toll on zeaxanthin plasma concentration in the retina, and over time, it degrades and decreases. Our eyesight then deteriorates. The good news is that human beings can alter the concentrations of retinal zeaxanthin, either through diet or supplementation.