Lutein

From Wikipedia, the free encyclopedia

Jump to: navigation, search
Lutein
IUPAC name
Other names Luteine; trans-lutein; 4-[18-(4-Hydroxy-2,6,6-trimethyl-1-cyclohexenyl) -3,7,12,16-tetramethyloctadeca-1,3,5,7,9,11,13,15,17-nonaenyl]-3,5,5-trimethyl-cyclohex-2-en-1-ol
Identifiers
CAS number [127-40-2]
PubChem 5368396
SMILES
Properties
Molecular formula C40H56O2
Molar mass 568.87 g mol−1
Appearance Red-orange crystalline solid
Solubility in water Insoluble
Solubility in fats Soluble
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox references

Lutein (pronounced /ˈluːtiːən/, /ˈluːtiːn/, /ˈluːtɪɪn/[1]; from Latin luteus meaning "yellow") is one of over 600 known naturally occurring carotenoids. Found in green leafy vegetables such as spinach and kale, lutein is employed by organisms as an antioxidant and for blue light absorption. Lutein is present in the plant as fatty-acid ester, with one or two fatty acids bound to the two hydroxyl-groups. Saponification of lutein esters yields lutein in approximately a 1:2 molar ratio. Lutein is also found in egg yolks, animal fats and the corpus luteum.[2] 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.

Contents

[edit] 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.

[edit] Role in human eyes

Lutein was found to be concentrated in 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.[3][4][5][6][7][8][9] Several studies also show that an increase in macula pigmentation decreases the risk for eye diseases such as Age-related Macular Degeneration (AMD).[10][11][12] The only randomized clinical trial to demonstrate a benefit for lutein in Macular Degeneration was a small study, in which the authors concluded that visual function is improved with lutein alone or lutein together with other nutrients and also that more study was needed .[11]

Lutein may also play a role in Haidinger's brush, an entoptic phenomenon that allows humans to detect polarized light.

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 6-10 mg/day.[13] 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 and is extracted from the petals of marigold (Tagetes erecta).[14]

Several researchers including a group led by John Paul SanGiovanni of the National Eye Institute, Maryland found that high intakes of Lutein and zeaxanthin (nutrients in eggs, spinach and other green vegetables) are associated with a lower risk of blindness (macular degeneration), affecting 1.2 million Americans, mostly after age 65. (journal Archives of Ophthalmology).

Whether this relation is causal and whether lutein and zeaxanthin actually reduce the risk of AMD is being studied.

Foods considered good sources of the nutrients also include kale, turnip greens, collard greens, romaine lettuce, broccoli, zucchini, corn, garden peas and Brussels sprouts.[15]


[edit] Relationship with diseases of the eye

There is epidemiological evidence of a relationship between low plasma concentrations of lutein and zeaxanthin on the one hand, and the risk of developing age-related macular degeneration (AMD) on the other. Some studies support the view that supplemental lutein and/or zeaxanthin help protect against AMD. There is also epidemiological evidence that increasing lutein and zeaxanthin intake lowers the risk of cataract development.[citation needed]

In 2007, in a 6-year study, 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 Americans, mostly after age 65. Lutein and zeaxanthin reduce the risk of AMD. Foods considered good sources of the nutrients also include kale, turnip greens, collard greens, romaine lettuce, broccoli, zucchini, corn, garden peas, swiss chard and Brussels sprouts.[16]

[edit] Commercial value

The lutein market is segmented into pharmaceutical, nutraceutical, food, pet foods, and animal 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, skins and as an antioxidant. It is one of the fastest growing areas of the US $2 billion carotenoid market.[17] There are several lutein ester suppliers, but few pure lutein (free form) suppliers such as Zhejiang Medicine Company (http://www.zmc-usa.com) and Omni Actives (http://www.omniactives.com) due primarily to patent (http://www.zmc-usa.com/docs/ZMC_Lutein_Patent_US7271298.pdf) protections on obtaining purified lutein from natural products, primarily marigolds.

[edit] References

  1. ^ Merriam-Webster's Online Dictionary: \ˈlü-tē-ən, ˈlü-ˌtēn\ (IPA equivalents: /ˈluːtiːən/, /ˈluːtiːn/); Oxford Dictionary of English, 2nd Ed.: /ˈluːtɪɪn/ (with two ɪ's)
  2. ^ Merriam-Webster Online Dictonary
  3. ^ Malinow, M.R., et al., Diet-related macular anomalies in monkeys. Invest Ophthalmol Vis Sci, 1980. 19(8): p. 857-63.
  4. ^ 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. PubMed Free text
  5. ^ Landrum, J., et al. Serum and macular pigment response to 2.4 mg dosage of lutein. in ARVO. 2000.
  6. ^ 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; PubMed Free text
  7. ^ 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. PubMed Free text
  8. ^ Duncan, J.L., et al., Macular pigment and lutein supplementation in choroideremia. Exp Eye Res, 2002. 74(3): p. 371-81. PubMed
  9. ^ 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. PubMed Free text
  10. ^ Richer, S., ARMD--pilot (case series) environmental intervention data. J Am Optom Assoc, 1999. 70(1): p. 24-36. PubMed
  11. ^ a b 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. PubMed
  12. ^ 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. PubMed
  13. ^ 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. PubMed
  14. ^ WHO/FAO Codex Alimentarius General Standard for Food Additives
  15. ^ Yahoo.com, Study finds spinach, eggs ward off cause of blindness
  16. ^ "Age-Related Eye Disease Study Research Group, SanGiovanni JP, Chew EY, et al.", The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report 125 (22): 1225–1232, 2007, doi:10.1001/archopht.125.9.1225, PMID 17846363 
  17. ^ FOD025C The Global Market for Carotenoids, BCC Research
v • d • e
Carotenoids
Carotenes (C40)
Xanthophylls (C40)
Apocarotenoids (C<40)
Vitamin A retinoids (C20)
Retinoid drugs
Retrieved from "http://en.wikipedia.org/wiki/Lutein"
Personal tools