Egg yolk contains two xanthophylls (carotenes that contain an alcohol group) that have important health benefits - lutein and zeaxanthin. It is estimated that a large egg contains 0.33 mg of lutein and zeaxanthin; however, the content of these xanthophylls is totally dependent on the type of feed provided to the hens. Egg-yolk lutein levels can be increased up to tenfold through modification of the feed with marigold extract or purified lutein. An indicator of the lutein + zeaxanthin content is the color of the yolk; the darker yellow-orange the yolk, the higher the xanthophyll content. Studies have shown that egg-yolk xanthophylls have a higher bioavailablity than those from plant sources, probably because the lipid matrix of the egg yolk facilitates greater absorption. This increased bio-availability results in significant increases in plasma levels of lutein and zeaxanthin as well as increased macular pigment densities with egg feeding.
Was this article helpful?