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
Photon energy to date, very-high-energy gamma rays, have photon energies of 100 GeV to 100 TeV (10 to 10 electronvolts) or 0.016 microjoules to 0.016 millijoules. This corresponds to frequencies of 2.42 × 10 to 2.42 × 10 Hz. A photon with a wavelength equal to the Planck length would have an energy of about 7.671 × 10 eV or 1.229 × 10 joules (12.29 gigajoules). This is roughly the amount of energy produced by the world's most powerful coal-fired power station, the Taichung Power Plant, during a period of 2.25 seconds. During photosynthesis, specific chlorophyll molecules absorb red-light photons at a