Lutein Lutein Lutein (; from Latin "luteus" meaning "yellow") is a xanthophyll and one of 600 known naturally occurring carotenoids. Lutein is synthesized only by plants and like other xanthophylls is found in high quantities in green leafy vegetables such as spinach, kale and yellow carrots. In green plants, xanthophylls act to modulate light energy and serve as non-photochemical quenching agents to deal with triplet chlorophyll (an excited form of chlorophyll), which is overproduced at very high light levels, during photosynthesis. See xanthophyll cycle for this topic. Lutein is obtained by animals by ingesting plants. In the human retina, lutein is
Photosynthesis light, oxidize cytochrome f, chlorophyll a (and other pigments) will absorb another light, but will reduce this same oxidized cytochrome, stating the two light reactions are in series. In 1893, Charles Reid Barnes proposed two terms, "photosyntax" and "photosynthesis", for the biological process of "synthesis of complex carbon compounds out of carbonic acid, in the presence of chlorophyll, under the influence of light". Over time, the term "photosynthesis" came into common usage as the term of choice. Later discovery of anoxygenic photosynthetic bacteria and photophosphorylation necessitated redefinition of the term. After WWII at late 1940 at the University of California,