From Joseph Mercola, DO
While there are about 850 known carotenoids, most are not found in the human body and only lutein, zeaxanthin and astaxanthin cross the blood-retina barrier to form macular pigment. Your retina is an extension of your brain, where lutein also accumulates throughout the human lifespan, hinting at its importance for both vision and cognitive function.
In fact, if you have dementia, you’re likely deficient in lutein, which crosses the bloodbrain barrier and has a protective, anti-inflammatory effect. While lutein is available in supplement form, it’s also found in a wide variety of foods, including dark leafy greens, avocados and egg yolks.
Lutein concentrates in your macula, which is the part of your retina responsible for central vision. Along with zeaxanthin and mesa-zeaxanthin (a metabolite of lutein), these three carotenoids form the retinal macular pigment, which not only is responsible for optimizing your visual performance but also serves as a biomarker for the risk of macular diseases.
Lutein is also found in the lens, where it helps protect against cataracts and other agerelated eye diseases. Among carotenoids, lutein is the most efficient at filtering out blue light — the type that comes from cellphones, computers, tablets and LED lights.