Dictionary:

lutein

  (lū'tē-ĭn, -tēn')

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1. A yellow carotenoid pigment, C₄₀H₅₆O₂, found widely in nature, first isolated in corpus luteum but later discovered in body fats, egg yolk, and green plants; xanthophyll.
2. A dried preparation of corpus luteum.

[Latin lūteum, yellow, egg yolk (from neuter of lūteus, yellow, from lūtum, yellowweed) + –IN.]

A hydroxylated carotenoid (xanthophyll); not vitamin A active, but an antioxidant.

Description

Found in certain fruits and vegetables as well as egg yolks, lutein is a nutrient with a number of potentially beneficial effects. It is a member of the carotenoid family, a group of chemicals related to vitamin A. While betacarotene, the precursor of vitamin A, may be the most familiar carotenoid, there are almost 600 others whose effects have yet to be extensively studied. Aside from lutein, these include alpha-carotene, lycopene, zeaxanthin, and beta-cryptoxanthin. In the plant world, carotenoids like lutein help to give color to sweet potatoes, carrots, and other fruits and vegetables. In people, lutein and zeaxanthin make up most of the pigment in the center of the retina, where vision sensitivity is greatest. While lutein is not considered an essential nutrient, studies suggest that it may play an important role in maintaining healthy vision and preventing eye diseases such as age-related macular degeneration (ARMD) and cataracts. Getting adequate amounts of this carotenoid may also decrease the risk of developing colon cancer and heart disease.

Lutein and other carotenoids are considered important because of their antioxidant properties. Antioxidants help to protect cells from damage caused by free radicals, the destructive fragments of oxygen produced as a byproduct during normal metabolic processes. As free radicals travel through the body, they cause damage to cells and genes by stealing electrons from other molecules—a process referred to as oxidation. Test tube studies conducted by the Agricultural Research Service of the United States Department of Agriculture (USDA) suggest that lutein may be just as effective at combating free radicals as vitamin E, which is a potent antioxidant. Concentrated mainly in the lens and retina of the eye, lutein may help to protect vision by neutralizing free radicals and by increasing the density of eye pigment. Lutein may also shield the eyes from the destructive effects of sunlight. In late 2001, a British study reported that risk of cortical cataract was lowest with high concentrations of lutein.

General Use

While not approved as a dietary supplement by the FDA, lutein is ubiquitous in foods. It may play an important role in maintaining vision and preventing such eye diseases as ARMD and cataracts, the two leading causes of vision loss in adults. The carotenoid may accomplish this by protecting eye tissue from free radical damage and shielding the eyes from potentially destructive sunlight. Research also indicates that getting adequate amounts of lutein may decrease the risk of colon cancer and heart disease. Lutein may offer protection against the latter two diseases by acting as an antioxidant, since free radical damage is believed to contribute to the development of cardiovascular disease as well as certain cancers.

The results of an earlier study, published in the British Medical Journal in 1992, shed light on the possible link between lutein and cataracts. The objective of the study was to examine the relationship between cataracts and intake of carotenoids, vitamins C and E, and riboflavin. Researchers studied the dietary habits via questionnaires of over 50,000 registered nurses aged 45 years and over for a period of eight years and found that those who reported consuming the most vitamin A and carotenoids were found to have a lower risk of developing cataracts. Spinach, which is a rich source of lutein, appeared to offer the most protection against the disease. The researchers concluded that the carotenoids present in food may decrease the risk of developing severe cataracts.

Lutein may also help to prevent the development of colon cancer, according to a study published in the American Journal of Clinical Nutrition in 2000. This study examined the risk of colon cancer and dietary intake of lutein and other carotenoids such as alpha-carotene, beta-carotene, lycopene, zeaxanthin, and beta-cryptoxanthin. The researchers examined the eating habits of over 4,000 people. Roughly half the participants were between the ages of 30 and 79 and already had colon cancer, while the remainder made up the cancer-free control group. The results indicated that men and women who had consumed large amounts of lutein were less likely to develop the disease. Interestingly, lutein was the only carotenoid identified by the study that seemed to offer any protection.

The evidence regarding lutein and heart disease is indirect but intriguing. A study reported in 2001 found that carotid arteries in those with higher lutein levels were clearer than average.

A human study also provides some indirect evidence that higher levels of lutein and other carotenoids may play a role in preventing the development of cardiovascular disease. The study, conducted by researchers from Cambridge University and published in 1996, examined blood levels of antioxidant vitamins and carotenoids in people from two regions of the world with very different rates of heart disease: Toulouse, France, and Belfast, Ireland. The results showed that residents of Toulouse, who have a much lower rate of heart disease, had lutein levels about twice as high as those from Belfast, where the incidence of cardiovascular disease is much greater. The people from Toulouse also had higher blood levels of other carotenoids.

Preparations

There is no RDA or Daily Value (DV) for lutein, and the optimum daily dosage has not been established with certainty. Therapeutic dosages range from 5–30 mg a day, though 6 mg daily is generally considered adequate. Some authorities believe it is better for people to avoid lutein supplements altogether and increase their intake of foods known to contain lutein. Egg yolks are the richest source and also contain a large amount of zeaxanthin. Other sources of lutein include corn, red seedless grapes, kiwi fruit, squash, and green vegetables such as zucchini, spinach, collard greens, kale, leaf lettuce, celery, peas, broccoli, and leeks. Oranges and orange juice, tomatoes, and carrots also prove good sources of lutein. In 2001, researchers reported that concentrations of lutein are higher in the peels of fruits than in the pulp. The concentration of carotenoids increases as fruit ripens. Getting too much lutein through food and drink is not considered a significant risk because the nutrient is only present in relatively small amounts in plants and animals.

Precautions

Lutein is not known to be harmful when taken in recommended dosages, though it is worth remembering that the long-term effects of taking lutein supplements are unknown. Due to lack of sufficient medical study, lutein should be used with caution in children, women who are pregnant or breast-feeding, and people with liver or kidney disease.

Side Effects

When taken in recommended dosages, lutein is not associated with any bothersome or significant side effects.

Interactions

Lutein is not known to interact adversely with any drugs or dietary supplements.

Resources

Books

Murray, Michael T. Encyclopedia of Nutritional Supplements. Rocklin, CA: Prima Publishing, 1996.

Periodicals

Carlson, Mike, et al. "Eat the Peel (Smart Nutrition)." Men's Fitness (October 2001): 20.

"Carotenoids May Protect Against Cataracts, Study Suggests." Angiogenesis Weekly (December 14, 2001): 9.

"Lutein: Not Just for Eyes." Nutrition Action Healthletter (October, 2001): 12.

Seddon J. M., U. A. Ajani, R. D. Sperduto, et al. "Dietary carotenoids, Vitamins A, C, and E, and Advanced Age-Related Macular Degeneration." Journal of the American Medical Association 272 no. 18 (1994): 1413–20.

Slattery M. L., J. Benson, K. Curtin, et al. "Carotenoids and Colon Cancer." American Journal of Clinical Nutrition 71 no. 2 (2000): 575–82.

Organizations

American Academy of Ophthalmology. PO Box 7424. San Francisco, CA 94120-7424. .

National Eye Institute. 2020 Vision Place. Bethesda, MD 20892-3655. .

Other

Discovery Health. .

[Article by: Greg Annussek; Teresa Norris]

1. a lipochrome from the corpus luteum, fat cells, and egg yolk.
2. any lipochrome.

Lutein
General
Synonyms	Luteine; 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
Carotenodermia
Common sources
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 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.

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.

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]. 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.^[9]

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 dietary intake 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 (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 Americans, mostly after age 65. Lutein and zeaxanthin reduce the risk of AMD (journal Archives of Ophthalmology). Foods considered good sources of the nutrients also include kale, turnip greens, collard greens, romaine lettuce, broccoli, zucchini, corn, garden peas and Brussels sprouts.^[1]

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 ^[12]. 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

1. Malinow, M.R., et al., Diet-related macular anomalies in monkeys. Invest Ophthalmol Vis Sci, 1980. 19(8): p. 857-63.
2. 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. 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. 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. 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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