Lutein

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Lutein


General
Synonyms Luteine; Lutein ester; trans-lutein; beta,epsilon-Carotene-3,3'-diol
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
CAS Number 127-40-2
Chemical formula C40H56O2
Chemical properties
Molecular weight 568.871 g/mol
Color Red-orange
Form Crystalline
Solubility Organic/fat soluble, aqueous insoluble
Molar absorption coefficient (EtOH) 255 ml/(mg*cm)
λmax 446 nm
Toxicity GRAS
Deficiency symptoms
  • Eye damage
  • Pale, dry skin
Excess symptoms
Common sources
  • Leafy vegetables
  • Egg yolk
  • Darkly colored fruits
  • Marigold petals

Lutein (LOO-teen) 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 covalently bound to one or more fatty acids present in some fruits and flowers, notably marigolds (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.

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] Health benefits for 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 [1-7]. Several studies also show that an increase in macula pigmentation decreases the risk for eye diseases such as Age-related Macular Degeneration (AMD) [8-10].

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, fortification via a sublingual spray ensures maximum benefit to the eyes. 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 levels of 6 mg/day [11]. The only definitive side effect of excess lutein consumption is the same observed for β-carotene overdose, namely bronzing of the skin (carotenodermia). The normal levels of Lutein found in a daily vitamin tablet can be as low as 0.25mg.

The functional difference between the benefits of lutein 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.

[edit] Commercial value

The commerciality of lutein has recently exploded with an estimated market value of $139 million in 2004, compared to $64 million in 1999. It is one of the fastest growing areas of the $887 million carotenoid market [12]. There are several lutein ester suppliers, but few pure lutein suppliers due primarily to patent protections on obtaining purified lutein from natural products, namely marigolds. Nevertheless, the market value of lutein is anticipated to grow at an average annual growth rate of over 6%.

[edit] References

  1. Malinow, M.R., et al., Diet-related macular anomalies in monkeys. Invest Ophthalmol Vis Sci, 1980. 19(8): p. 857-63.
  2. 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
  3. Landrum, J., et al. Serum and macular pigment response to 2.4 mg dosage of lutein. in ARVO. 2000.
  4. 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
  5. 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
  6. Duncan, J.L., et al., Macular pigment and lutein supplementation in choroideremia. Exp Eye Res, 2002. 74(3): p. 371-81. PubMed
  7. 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
  8. Richer, S., ARMD--pilot (case series) environmental intervention data. J Am Optom Assoc, 1999. 70(1): p. 24-36. PubMed'
  9. 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
  10. 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
  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. PubMed
  12. a  GA-110R The Global Market for Carotenoids, Business Communications Company, Inc.
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