View source for Lutein

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|-
| align="center" colspan="2" |  ''Lutein''
<br />
[[Image:lutein.png|none|300px]]
|- style="border-top: 3px solid gray"
! bgcolor="#ffddaa" colspan="2" | General
|-
| bgcolor="#ffeedd" | Synonyms
| Luteine; trans-lutein; beta, epsilon-Carotene-3,3'-diol
|-
| bgcolor="#ffeedd" | [[IUPAC]] Name
| 4-[18-(4-hydroxy-2,6,6-trimethyl-1-cyclohexenyl) -3,7,12,16-tetramethyl-octadeca -1,3,5,7,9,11,13,15,17-nonaenyl] -3,5,5-trimethyl-cyclohex-2-en-1-ol
|-
| bgcolor="#ffeedd" | [[CAS Number]]
| 127-40-2
|-
| bgcolor="#ffeedd" | [[Chemical formula]]
| C<sub>40</sub>H<sub>56</sub>O<sub>2</sub>
|-
! bgcolor="#ffddaa" colspan="2" | Chemical properties
|-
| bgcolor="#ffeedd" | [[Molecular weight]]
| 568.871 g/mol
|-
| bgcolor="#ffeedd" | Color
| Red-orange
|-
| bgcolor="#ffeedd" | Form
| Crystalline
|-
| bgcolor="#ffeedd" | [[Solubility]]
| Organic/fat soluble, aqueous insoluble
|-
| bgcolor="#ffeedd" | [[Beer-Lambert law|Molar absorption coefficient]] (EtOH)
| 255 ml/(mg*cm)
|-
| bgcolor="#ffeedd" | λ<sub>max</sub>
| 446 nm
|-
| bgcolor="#ffeedd" | Toxicity
| [[GRAS]]
|-
! bgcolor="#ffeedd" colspan="2" | Deficiency symptoms
|-
| colspan="2" |
* Eye damage
* Pale, dry skin
|-
! bgcolor="#ffeedd" colspan="2" | Excess symptoms
|-
| colspan="2" |
* [[Carotenodermia]]
|-
! bgcolor="#ffddaa" colspan="2" | Common sources
|-
| colspan="2" |
* Leafy vegetables
* Egg yolk
* Darkly colored fruits
* Marigold petals
|-
|}

'''Lutein''' (LOO-teen) (from [[Latin]] ''lutea'' meaning "yellow") is one of over 600 known naturally occurring [[carotenoid]]s. Found in [[green leafy vegetable]]s such as [[spinach]] and [[kale]], lutein is employed by organisms as an [[antioxidant]] and for blue light absorption. Lutein is [[covalent bond|covalently bound]] to one or more [[fatty acid]]s present in some fruits and flowers, notably [[marigold]]s (Tagetes). [[Saponification]] of lutein [[esters]] yields lutein in approximately a 2:1 weight-to-weight conversion.

Lutein is a [[lipophilic]] molecule and is generally insoluble in water. The presence of the long [[chromophore]] of conjugated double bonds ([[polyene]] chain) provides the distinctive light-absorbing properties.  The polyene chain is susceptible to oxidative degradation by light or heat and is chemically unstable in acids.  

The principal natural [[stereoisomer]] of lutein is         
(3R,3'R,6'R)-beta, epsilon-Carotene-3,3'-diol.

==As a pigment==
This [[xanthophyll]], like its sister compound [[zeaxanthin]], has primarily been used as a natural colorant due to its [[orange-red]] [[color]]. Lutein absorbs [[blue]] light and therefore appears [[yellow]] at low concentrations and orange-red at high concentrations.

Lutein was traditionally used in [[chicken]] feed to provide the yellow color of [[broiler]] chicken skin.  Polled consumers viewed yellow chicken skin more favorably than white chicken skin. Such lutein fortification also results in a darker yellow [[egg yolk]]. Today the coloring of the egg yolk has become the primary reason for feed fortification.  Lutein is not used as a [[colorant]] in other foods due to its limited stability, especially in the presence of other dyes.

==Role in human eyes==
Lutein was found to be present in a concentrated area of the [[macula]], a small area of the retina responsible for central vision. The hypothesis for the natural concentration is that lutein helps protect from oxidative stress and high-energy light. Various research studies have shown that a direct relationship exists between lutein intake and pigmentation in the eye <sup>[1-7]</sup>. Several studies also show that an increase in macula pigmentation decreases the risk for eye diseases such as Age-related [[Macular Degeneration]] (AMD) <sup>[8-10]</sup>. The only randomized clinical trial to demonstrate a benefit for lutein in [[Macular Degeneration]] was a small study, in which the authors concluded that more study was needed.<sup>[9]</sup>

Lutein is a natural part of human diet when fruits and vegetables are consumed. For individuals lacking sufficient lutein intake, lutein-fortified foods are available, or in the case of elderly people with a poorly absorbing digestive system, a [[sublingual]] spray is available. As early as 1996, lutein has been incorporated into dietary supplements.  While no [[recommended daily allowance]] currently exists for lutein as for other nutrients, positive effects have been seen at dietary intake levels of 6 mg/day {{ref_N|11|a}}. The only definitive side effect of excess lutein consumption is bronzing of the skin ([[carotenodermia]]).

The functional difference between lutein (free form) and lutein esters is not entirely known. It is suggested that the [[bioavailability]] is lower for lutein esters, but much debate continues.

As a [[food additive]], lutein has the [[E number]] E161b.

On September 10, 2007, in a 6-year study, [[researchers]], led by John Paul SanGiovanni of the [[National Eye Institute]], [[Maryland]] found that Lutein and [[zeaxanthin]] ([[nutrients]] in [[eggs]], [[spinach]] and other [[green]] [[vegetables]]) protect against [[blindness]] ([[macular degeneration]]), affecting 1.2 million [[United States|Americans]], mostly after age 65. Lutein and zeaxanthin reduce the risk of [[macular degeneration|AMD]] ([[journal]] [[Archives of Ophthalmology]]). Foods considered good sources of the nutrients also include [[kale]], [[turnip]] [[leaf vegetables|greens]], [[collard]] greens, [[romaine lettuce]], [[broccoli]], [[zucchini]], [[corn]], [[garden]] [[peas]] and [[Brussels sprouts]].<ref>[http://news.yahoo.com/s/nm/20070910/hl_nm/eyesight_nutrients_dc;_ylt=AhJwo077jBEbQvMoRIMIxV2s0NUE  Yahoo.com, Study finds spinach, eggs ward off cause of blindness]</ref>

==Commercial value==
The Lutein market is segmented into Pharmaceutical, Nutraceutical, Food, Pet Foods and Animal Feed and Fish Feed. The Pharmaceutical market is estimated to be about US $ 190 Million, Nutraceutical and Food is estimated to be about US $ 110 Million. Pet foods and other applications are estimated at US $ 175 Million annually.  Apart from the customary Age related Macular Degeneration applications , newer applications are emerging in Cosmetics, Skin Care and as an Antioxidant.  It is one of the fastest growing areas of the $ 2 Billion carotenoid market {{ref_N|12|a}}. There are several lutein ester suppliers, but few pure lutein (Free Form) suppliers due primarily to patent protections on obtaining purified Lutein from natural products, namely marigolds. Companies like Indus Biotech Pvt. Ltd, OmniActive Health Technologies and Kemin Industries have patents.  The market size of lutein is anticipated to grow at an average annual growth rate of over 22%.

==References==

# Malinow, M.R., ''et al.'', Diet-related macular anomalies in monkeys. Invest Ophthalmol Vis Sci, 1980. 19(8): p. 857-63.
# [[Image:Free_text.png]] Johnson, E.J., ''et al.'', Relation among serum and tissue concentrations of lutein and zeaxanthin and macular pigment density. ''Am J Clin Nutr. 2000 Jun; 71(6): 1555-62. {{PMID|10837298}}'' [http://www.ajcn.org/cgi/content/full/71/6/1555 Free text] 
# Landrum, J., ''et al.'' Serum and macular pigment response to 2.4 mg dosage of lutein. in ARVO. 2000.
# [[Image:Free_text.png]] Berendschot, T.T., ''et al.'', Influence of lutein supplementation on macular pigment, assessed with two objective techniques. ''Invest Ophthalmol Vis Sci. 2000 Oct. 41(11): 3322-6; {{PMID|11006220}}'' [http://www.iovs.org/cgi/content/full/41/11/3322 Free text] 
# [[Image:Free_text.png]] Aleman, T.S., ''et al.'', Macular pigment and lutein supplementation in retinitis pigmentosa and Usher syndrome. ''Invest Ophthalmol Vis Sci. 2001 Jul; 42(8): 1873-81. {{PMID|11431456}}'' [http://www.iovs.org/cgi/content/full/42/8/1873 Free text]
# Duncan, J.L., ''et al.'', Macular pigment and lutein supplementation in choroideremia. ''Exp Eye Res, 2002. 74(3): p. 371-81. {{PMID|12014918}}''
# [[Image:Free_text.png]] Johnson, E.J., ''et al.'', Nutritional manipulation of primate retinas, III: Effects of lutein or zeaxanthin supplementation on adipose tissue and retina of xanthophyll-free monkeys. ''Invest Ophthalmol Vis Sci, 2005. 46(2): p. 692-702. {{PMID|15671301}}'' [http://www.iovs.org/cgi/content/full/46/2/692 Free text]
# Richer, S., ARMD--pilot (case series) environmental intervention data. ''J Am Optom Assoc, 1999. 70(1): p. 24-36. {{PMID|10457679}}'
# Richer, S., ''et al.'', Double-masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration: the Veterans LAST study (Lutein Antioxidant Supplementation Trial). ''Optometry, 2004. 75(4): p. 216-30. {{PMID|15117055}}''
# A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age- related macular degeneration and vision loss: AREDS report no. 8. ''Arch Ophthalmol, 2001. 119(10): p. 1417-36. {{PMID|11594942}}''
# {{note_N|11|a}} Seddon, J.M., ''et al.'', Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. ''JAMA, 1994. 272(18): p. 1413-20. {{PMID|7933422}}''
# {{note_N|12|a}} GA-110R The Global Market for Carotenoids, [http://www.bccresearch.com Business Communications Company, Inc.] 

[[Category:Carotenoids]]
[[Category:Food antioxidants]]
[[Category:Dietary antioxidants]]

[[bg:Лутеин]]
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[[ja:カロテノイド#.E3.83.AB.E3.83.86.E3.82.A4.E3.83.B3]]
[[pl:Luteina (barwnik)]]
[[sv:Lutein]]