Zeaxanthin
Encyclopedia
Zeaxanthin is one of the most common carotenoid alcohols found in nature. It is important in the xanthophyll cycle. Synthesized in plants & some micro-organisms, it is the pigment that gives paprika
(made from bell peppers), corn
, saffron
, and many other plants & microbes their characteristic color.
The name is derived from Zea mays (common yellow maize corn) in which zeaxanthin provides the primary yellow pigment, plus the Greek word for yellow (see xanthophyll
).
Xanthophylls such as zeaxhanthin are found in highest quantity in the leaves
of most green plants, where they act to modulate light energy and perhaps serve as a non-photochemical quenching
agent to deal with triplet chlorophyll (an excited form of chlorophyll), which is overproduced at very high light levels, during photosynthesis.
Animals derive zeaxanthin from a plant diet. Zeaxanthin is one of the two primary xanthophyll
carotenoid
s contained within the retina
of the eye
. Within the central macula
, zeaxanthin is the dominant component, whereas in the peripheral retina, lutein
predominates.
As a food additive
, zeaxanthin is a food dye with E number
E161h.
s, but they are not stereoisomers. The only difference between them is in the location of the double bond
in one of the end rings. This difference gives lutein three chiral
centers whereas zeaxanthin has two. Because of symmetry, the (3R,3'S) and (3S,3'R) stereoisomers of zeaxanthin are identical. Therefore, zeaxanthin has only three stereoisomeric forms. The (3R,3'S) stereoisomer is called meso-zeaxanthin.
The principal natural form of zeaxanthin is (3R,3'R)-zeaxanthin. The macula mainly contains the (3R,3'R)- and meso-zeaxanthin forms, but it also contains much smaller amounts of the third (3S,3'S) form.
have connected high dietary intake of foods providing zeaxanthin with lower incidence of age-related macular degeneration (AMD), most notably the Age-Related Eye Disease study (AREDS). There is currently insufficient evidence to assess the effectiveness of dietary or supplemental
antioxidants in treatment or primary prevention of ARMD, or the formation or progression of cataract
s. Any benefit is more likely to be apparent in subpopulations of individuals exposed to high oxidative stress, such as heavy smokers or those with poor nutrition. In 2005, the US Food and Drug Administration
rejected a Qualified Health Claims application by Xangold, citing insufficient evidence supporting the use of a zeaxanthin-containing supplement in prevention of AMD.
(made from bell peppers), corn
, saffron
, and many other plants their characteristic color. Zeaxanthin breaks down to form picrocrocin
and safranal
, which are responsible for the taste and aroma of saffron.
Foods considered good sources of lutein and zeaxanthin include eggs
, spinach
, goji berry, kale
, turnip
greens
, collard greens, romaine lettuce
, broccoli
, zucchini
, kiwifruit
, corn
, garden peas
, swiss chard and Brussels sprouts.
Paprika
Paprika is a spice made from the grinding of dried fruits of Capsicum annuum . In many European languages, the word paprika refers to bell peppers themselves. The seasoning is used in many cuisines to add color and flavor to dishes. Paprika can range from mild to hot...
(made from bell peppers), corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, saffron
Saffron
Saffron is a spice derived from the flower of Crocus sativus, commonly known as the saffron crocus. Crocus is a genus in the family Iridaceae. Each saffron crocus grows to and bears up to four flowers, each with three vivid crimson stigmas, which are each the distal end of a carpel...
, and many other plants & microbes their characteristic color.
The name is derived from Zea mays (common yellow maize corn) in which zeaxanthin provides the primary yellow pigment, plus the Greek word for yellow (see xanthophyll
Xanthophyll
Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos + phyllon , due to their formation of the yellow band seen in early chromatography of leaf pigments...
).
Xanthophylls such as zeaxhanthin are found in highest quantity in the leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
of most green plants, where they act to modulate light energy and perhaps serve as a non-photochemical quenching
Non-photochemical quenching
Non-photochemical quenching is a mechanism employed by plants and algae to protect themselves from the adverse effects of high light intensity. It involves the quenching of singlet excited state chlorophylls via enhanced internal conversion to the ground state , thus harmlessly dissipating...
agent to deal with triplet chlorophyll (an excited form of chlorophyll), which is overproduced at very high light levels, during photosynthesis.
Animals derive zeaxanthin from a plant diet. Zeaxanthin is one of the two primary xanthophyll
Xanthophyll
Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos + phyllon , due to their formation of the yellow band seen in early chromatography of leaf pigments...
carotenoid
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
s contained within the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
of the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
. Within the central macula
Macula
The macula or macula lutea is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells...
, zeaxanthin is the dominant component, whereas in the peripheral retina, lutein
Lutein
Lutein 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 and kale...
predominates.
As a food additive
Food additive
Food additives are substances added to food to preserve flavor or enhance its taste and appearance.Some additives have been used for centuries; for example, preserving food by pickling , salting, as with bacon, preserving sweets or using sulfur dioxide as in some wines...
, zeaxanthin is a food dye with E number
E number
E numbers are number codes for food additives that have been assessed for use within the European Union . They are commonly found on food labels throughout the European Union. Safety assessment and approval are the responsibility of the European Food Safety Authority...
E161h.
Isomers
Lutein and zeaxanthin have identical chemical formulas and are isomerIsomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...
s, but they are not stereoisomers. The only difference between them is in the location of the double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...
in one of the end rings. This difference gives lutein three chiral
Chirality (chemistry)
A chiral molecule is a type of molecule that lacks an internal plane of symmetry and thus has a non-superimposable mirror image. The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom....
centers whereas zeaxanthin has two. Because of symmetry, the (3R,3'S) and (3S,3'R) stereoisomers of zeaxanthin are identical. Therefore, zeaxanthin has only three stereoisomeric forms. The (3R,3'S) stereoisomer is called meso-zeaxanthin.
The principal natural form of zeaxanthin is (3R,3'R)-zeaxanthin. The macula mainly contains the (3R,3'R)- and meso-zeaxanthin forms, but it also contains much smaller amounts of the third (3S,3'S) form.
Relationship with diseases of the eye
Several observational studiesObservational study
In epidemiology and statistics, an observational study draws inferences about the possible effect of a treatment on subjects, where the assignment of subjects into a treated group versus a control group is outside the control of the investigator...
have connected high dietary intake of foods providing zeaxanthin with lower incidence of age-related macular degeneration (AMD), most notably the Age-Related Eye Disease study (AREDS). There is currently insufficient evidence to assess the effectiveness of dietary or supplemental
Dietary supplement
A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...
antioxidants in treatment or primary prevention of ARMD, or the formation or progression of cataract
Cataract
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
s. Any benefit is more likely to be apparent in subpopulations of individuals exposed to high oxidative stress, such as heavy smokers or those with poor nutrition. In 2005, the US Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
rejected a Qualified Health Claims application by Xangold, citing insufficient evidence supporting the use of a zeaxanthin-containing supplement in prevention of AMD.
Natural occurrence
Zeaxanthin is one of the most common carotenoid alcohols found in nature. It is the pigment that gives paprikaPaprika
Paprika is a spice made from the grinding of dried fruits of Capsicum annuum . In many European languages, the word paprika refers to bell peppers themselves. The seasoning is used in many cuisines to add color and flavor to dishes. Paprika can range from mild to hot...
(made from bell peppers), corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, saffron
Saffron
Saffron is a spice derived from the flower of Crocus sativus, commonly known as the saffron crocus. Crocus is a genus in the family Iridaceae. Each saffron crocus grows to and bears up to four flowers, each with three vivid crimson stigmas, which are each the distal end of a carpel...
, and many other plants their characteristic color. Zeaxanthin breaks down to form picrocrocin
Picrocrocin
Picrocrocin is a monoterpene glycoside precursor of safranal. It is found in the spice saffron, which comes from the crocus flower. Picrocrocin has a bitter taste and is the chemical most responsible for the taste of saffron....
and safranal
Safranal
Safranal is an organic compound isolated from saffron, the spice consisting of the stigmas of crocus flowers . It is the constituent primarily responsible for the aroma of saffron....
, which are responsible for the taste and aroma of saffron.
Foods considered good sources of lutein and zeaxanthin include eggs
Egg (food)
Eggs are laid by females of many different species, including birds, reptiles, amphibians, and fish, and have probably been eaten by mankind for millennia. Bird and reptile eggs consist of a protective eggshell, albumen , and vitellus , contained within various thin membranes...
, spinach
Spinach
Spinach is an edible flowering plant in the family of Amaranthaceae. It is native to central and southwestern Asia. It is an annual plant , which grows to a height of up to 30 cm. Spinach may survive over winter in temperate regions...
, goji berry, kale
Kale
Kale is very high in beta carotene, vitamin K, vitamin C, lutein, zeaxanthin, and reasonably rich in calcium. Kale, as with broccoli and other brassicas, contains sulforaphane , a chemical with potent anti-cancer properties. Boiling decreases the level of sulforaphane; however, steaming,...
, turnip
Turnip
The turnip or white turnip is a root vegetable commonly grown in temperate climates worldwide for its white, bulbous taproot. Small, tender varieties are grown for human consumption, while larger varieties are grown as feed for livestock...
greens
Leaf vegetable
Leaf vegetables, also called potherbs, green vegetables, greens, leafy greens or salad greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots...
, collard greens, romaine lettuce
Romaine lettuce
Romaine or cos lettuce is a variety of lettuce which grows in a tall head of sturdy leaves with a firm rib down the center. Unlike most lettuces, it is tolerant of heat...
, broccoli
Broccoli
Broccoli is a plant in the cabbage family, whose large flower head is used as a vegetable.-General:The word broccoli, from the Italian plural of , refers to "the flowering top of a cabbage"....
, zucchini
Zucchini
The zucchini is a summer squash which often grows to nearly a meter in length, but which is usually harvested at half that size or less. It is a hybrid of the cucumber. Along with certain other squashes, it belongs to the species Cucurbita pepo. Zucchini can be dark or light green...
, kiwifruit
Kiwifruit
The kiwifruit, often shortened to kiwi in many parts of the world, is the edible berry of a cultivar group of the woody vine Actinidia deliciosa and hybrids between this and other species in the genus Actinidia....
, corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, garden peas
PEAS
P.E.A.S. is an acronym in artificial intelligence that stands for Performance, Environment, Actuators, Sensors.-Performance:Performance is a function that measures the quality of the actions the agent did....
, swiss chard and Brussels sprouts.