LUTEIN STORY |
| Monday, 7th April 2008 |
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The Lutein "White Paper" was researched by Melvin Baron, PharmD, MPA, FACA, FCPHA, Associate Professor of Clinical Pharmacy. What Are Carotenoids? Carotenoids are a large group of natural plant compounds that provide yellow, orange, and red colors to many foods and plants. Carotenoids perform several important functions in plants. They harvest light energy for photosynthesis, protect against sunlight-induced damage, and provide colors that attract pollinating insects.1 Carotenoids are important for human health as well as plant health. The major carotenoids consumed in the diet are alpha-carotene, beta-carotene, lycopene, lutein, zeaxanthin, and beta-cryptoxanthin. Those found in the highest concentrations in human blood are beta-carotene, lycopene, and lutein.2 Because the body cannot manufacture carotenoids, all carotenoids that appear in the bloodstream originate from the diet (foods or dietary supplements). Some of the carotenoids are converted into vitamin A in the body and can satisfy the body’s need for this essential vitamin. Other carotenoids act as antioxidants, enhance the immune system, and protect the eye against light damage.2 Diets rich in carotenoids are associated with a lower risk of heart disease, certain types of cancer, and age-related eye diseases.2 A carotenoid-rich diet requires an abundance of colorful fruits and vegetables. However, the average American fails to meet even the minimum recommendation of 5 servings of fruits and vegetables each day. The United States Department of Agriculture (USDA) reports that only about a third of the population eats 5 or more servings of fruits and vegetables each day, and a large proportion of the population does not eat a single serving of fruit on any given day.3 What Are Lutein and Zeaxanthin? Lutein and zeaxanthin are yellow-colored carotenoids. They belong to the group of carotenoids known as xanthophylls. Like other carotenoids, lutein and zeaxanthin have antioxidant activity in the body. Unlike other carotenoids, lutein and zeaxanthin cannot be converted to vitamin A in the body. Lutein and zeaxanthin are unique among the carotenoids because they are concentrated in the retina of the eye. They make up the macula or “yellow spot” in the center of the retina, which is responsible for detailed, central vision. Although up to 20 carotenoids can be detected in the blood, only lutein and zeaxanthin appear in the macula.4-5 Dark green, leafy vegetables like spinach, kale, and collard greens are the richest sources of lutein and zeaxanthin. Broccoli, brussels sprouts, peas, corn, and egg yolks are good sources of lutein, and egg yolks, corn, orange peppers, and persimmons are good sources of zeaxanthin. Even though tomatoes, lettuce, carrots, and orange juice are not particularly rich sources of lutein and zeaxanthin, they provide a significant amount of lutein and zeaxanthin in the daily diet because they are more commonly eaten on a regular basis.4, 6 Fruits and vegetables typically contain much larger amounts of lutein than zeaxanthin. Although lutein and zeaxanthin are nearly identical in structure, they are not interchangeable in the body. Although there is a theoretical pathway for the conversion of lutein to zeaxanthin and zeaxanthin to lutein, it is not clear if this interconversion actually takes place to any extent.7 Age-Related Eye Diseases Poorer vision is a normal part of the aging process. In addition to causing a decline in eyesight, aging also greatly increases the risk of two types of eye diseases – age-related macular degeneration and cataract. Rates of these two eye diseases are increasing as the percentage of elderly people in the population increases. Age-Related Macular Degeneration (AMD) AMD is the leading cause of blindness in people aged 65 years and older. Nearly 2 million people have AMD and another 7 million people are at high risk for developing AMD. These figures are expected to triple in the next 30-40 years as the population ages.8 AMD is caused by a painless deterioration of the retina, which is the part of the eye that relays images to the brain. The center of the retina is called the macula. The macula is responsible for the detailed central vision that allows people to read, drive, and recognize faces. If the macula starts to break down, areas in the center of the visual field look blurry. As AMD progresses, vision become more blurred and distorted and blindness may occur. Smoking, obesity, exposure to sunlight, female gender, Caucasian race, blue or green eye color, heart disease, and a family history of AMD all increase the risk of developing AMD.9-10 About 85-90% of people with AMD have “dry” AMD. In dry AMD, the macula thins and dries out, which in turn leads to a loss of macular function and causes a gradual loss of vision. “Wet” AMD occurs in about 15% of people. In wet AMD, abnormal blood vessels beneath the macula leak fluid, causing the retina to become distorted. Vision deteriorates rapidly with wet AMD. Dry AMD can progress to wet AMD when new blood vessels are formed to improve the blood supply to the retina.9 People with wet AMD are twice as likely to fall and injure themselves and four times as likely to need assistance with daily activities as people without AMD. AMD leads to a decline in the quality of life and increases utilization of health care resources.11 There is currently no cure for AMD, and treatment to limit the progression of the disease is temporary or ineffective in many people. Prevention of AMD at an early stage may be the only effective way to reduce the personal and public health burden of AMD. Cataract A cataract is a cloudiness of the lens in the eye. The lens, which is clear and transparent in the healthy eye, focuses the light entering the pupil onto the retina in the back of the eye. Aging gradually causes protein fibers in the lens to accumulate and the lens becomes cloudy. A cloudy lens scatters the light and prevents a sharp image from reaching the retina. Cataracts are painless and the most common symptoms of a cataract are blurred or dim vision, sensitivity to glare, and seeing halos around lights.12 Half of people who are 65 years of age have cloudiness in the lens that affects their vision. Aging, smoking, alcohol consumption, diabetes, exposure to sunlight, and a family history of cataract all increase the risk of developing a cataract. Cataracts are the leading cause of impaired vision and are a major cause of disability.12 Lutein and Zeaxanthin
What Do Lutein and Zeaxanthin Do? Lutein and zeaxanthin play similar roles in plants and in humans. The two major roles of lutein and zeaxanthin in humans are: 1. Photoprotection – protection against damage caused by excess light exposure 2. Antioxidant – protection against damage caused by highly reactive molecules Eye Photoprotection The physical structure of lutein and zeaxanthin allows them to trap and absorb light from a particular portion of the visible light spectrum. The eyes are continuously exposed to light and are vulnerable to damage from light energy. The retina lines the back of the eye and it is sensitive to light exposure. The retina converts light into electrical impulses that are sent to the brain. Lutein and zeaxanthin make up the macular pigment found in the macula (the center of the retina). The macular pigment traps and filters out much of the higher-energy blue light before it reaches the delicate structures of the retina. It is estimated that lutein and zeaxanthin reduce the intensity of blue light in the retina by 40-90%.4 Antioxidant A dietary antioxidant is defined as a substance in foods that significantly decreases the harmful effects of highly reactive molecules on normal physiological function in humans.2 Lutein, zeaxanthin, and other carotenoids are natural dietary antioxidants and are among the most efficient scavengers of singlet oxygen. Singlet oxygen is a highly reactive type of oxygen that can damage proteins, fats, DNA, and other biological molecules. Lutein and zeaxanthin are easily oxidized and thereby “sacrifice” themselves to protect these important biological molecules.4, 13 Damage caused by oxidation appears to contribute to the development of many chronic diseases, including cancers, heart disease, cataracts, and age-related macular degeneration.5 The skin and eyes are continually exposed to light and ultraviolet (UV) radiation from the sun and are vulnerable to light-induced damage. Oxidative stress occurs in the eye because of the intense light exposure and the high rate of oxidative metabolism.8 The retina is particularly vulnerable because it requires a rich supply of oxygen and has delicate structures that are exposed to high-energy blue light.5 Oxidation of proteins in the lens plays a role in the formation of age-related cataracts. Skin exposure to sunlight triggers a cascade of reactions that can produce reactive oxygen species and lead to sunburn, skin damage, and skin cancer. Lutein and zeaxanthin are found in the skin and several parts of the eye, where they appear to provide antioxidant protection from sunlight-induced oxidation reactions. What Research Has Been Conducted on Lutein and Zeaxanthin? Lutein and zeaxanthin have been investigated in laboratory studies, animal studies, observational studies in humans, and intervention studies in humans (clinical trials). Supplementation with lutein plus zeaxanthin has been shown to significantly increase the blood levels of both carotenoids.14-17 Supplementation also significantly increases the density of the macular pigment in the eye.15-18 Higher intakes of lutein and zeaxanthin are associated with increased levels in the blood and greater macular pigment density.19 Because diet strongly influences the density of the macular pigment, a wide range of macular pigments densities is found in the normal population.20 Studies of eyes from deceased donors have shown that people with AMD have lower levels of lutein and zeaxanthin in the macula than people without AMD.5 Observational Studies In these studies, researchers observe a group of people to see what changes have occurred or will occur in their health. These studies may demonstrate an association between a risk factor or variable (such as lutein and zeaxanthin intake) and a condition or disease (such as age-related macular degeneration). Although an association may be observed, these studies do not prove cause and effect. 1. Age-Related Macular Degeneration (AMD) • Eye Disease Case-Control Study21, 22 i. Examined the relationship between AMD and dietary intake of carotenoids, vitamin A, vitamin C, and vitamin E ii. Conducted among 876 people with and without wet AMD, aged 55 to 80 years, in the United States iii. Higher dietary intakes of carotenoids were associated with a lower risk of AMD; the risk of developing AMD was 43% lower in those with the highest intakes compared to those with the lowest intakes iv.Lutein and zeaxanthin were the carotenoids most strongly associated with a reduced risk for AMD •Beaver Dam Eye Study23 i.Examined the relationship between antioxidants (lutein and zeaxanthin, alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, vitamin E, and vitamin C) and zinc intake and the incidence of early stages of AMD ii.Conducted among 1,709 middle-aged and older participants in the Beaver Dam Eye Study in the United States iii.None of the antioxidants, including lutein and zeaxanthin, were associated with early AMD during a 5-year follow up period iv.Higher intakes of the pro-vitamin A carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin) and vitamin E were associated with lower incidence of large drusen (deposits on the retina that may indicate early AMD); higher intakes of zinc were associated with fewer pigment abnormalities •Third National Health and Nutrition Examination Survey (NHANES III)24 i.Examined the relationship between lutein and zeaxanthin (dietary intake and blood levels) and AMD ii.Conducted among 8,222 people aged 40 years and older in the United States iii.No association between dietary or blood lutein and zeaxanthin and AMD was found in the overall population iv.Higher intakes of lutein and zeaxanthin were associated with a lower risk of an early AMD lesion in people aged 40 to 59 years and a lower risk of late AMD in people aged 60 to 79 years •Age-Related Eye Disease Study (AREDS)25 i.Examined the relationships between dietary carotenoids, vitamin A, vitamin E, vitamin C, and prevalence of AMD ii.Conducted among 4,519 people, aged 60-80 years, in the United States iii.Higher intakes of dietary lutein and zeaxanthin were associated with a lower risk of AMD iv.No association was found between vitamins A, E, or C and risk of AMD •Carotenoids in Age-Related Eye Disease Study (CAREDS)26, 27 i.Examined the relationships between dietary lutein and zeaxanthin intake, blood levels of lutein and zeaxanthin, macular pigment density, and AMD ii.Conducted among 1,787 women, aged 50-86 years, in the United States iii.Macula pigment density was 30% higher in women with the highest intakes of lutein and zeaxanthin compared to women with the lowest intakes iv.Macular pigment density is associated with dietary lutein and zeaxanthin and strongly associated with blood levels of lutein and zeaxanthin v.No differences in AMD prevalence were found overall between women with high intakes of lutein and zeaxanthin and women with low intakes; for a subgroup of healthy women younger than 75 years who had maintained a consistent intake of lutein and zeaxanthin, the risk of AMD was 43% lower for those with high intakes compared to those with low intakes 2. Cataract •Beaver Dam Eye Study28 i.Examined the relationship between antioxidants (lutein and zeaxanthin, alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, vitamin C, and vitamin E) and cataracts ii.Conducted among 1,354 people, aged 43-84 years, participating in the Beaver Dam Eye Study in the United States iii.People with the highest intake of lutein and zeaxanthin in the distant past were half as likely to develop cataracts compared to people with the lowest intakes iv.Lutein and zeaxanthin were the only carotenoids associated with a reduced risk of cataract •Nurses’ Health Study29 i.Examined the association between dietary carotenoid and vitamin A intakes and cataract surgery over a 12-year period ii.Conducted among 77,466 female nurses, aged 45-71 years, in the United States iii.Women with the highest intakes of lutein and zeaxanthin had a 22% lower risk of cataract surgery compared to women with the lowest intakes iv.No associations were observed for other carotenes (alpha-carotene, beta-carotene, lycopene, or beta-cryptoxanthin) or vitamin A v.Increased frequency of eating spinach and kale was associated with a moderate decrease in risk of cataract •Health Professionals Follow-up Study30 i.Examined the association between dietary carotenoid and vitamin A intakes and cataract surgery over an 8-year period ii.Conducted among 36,644 male health professionals, aged 45-75 years, in the United States iii.Men with the highest intakes of lutein and zeaxanthin had a 19% lower risk of cataract surgery compared to men with the lowest intakes iv.No associations were observed for other carotenes (alpha-carotene, beta-carotene, lycopene, or beta-cryptoxanthin) or vitamin A v.Increased frequency of eating broccoli and spinach was associated with a lower risk of cataract 3. Skin Health •Nambour Skin Cancer Study31 i.Examined the relationship between dietary intake of antioxidants and risk of skin cancer ii.Conducted among 1,001 adults in Australia iii.Higher intakes of lutein and zeaxanthin were associated with a 50% reduction in squamous cell carcinoma in people with a history of skin cancer Clinical Trials In these studies, researchers intervene by giving research subjects the product or treatment in question and assessing the outcome. Researchers try to eliminate or control for variables that may influence the outcome. Because other variables are controlled, the outcomes can generally be attributed to the intervention (cause and effect). 1. Age-Related Macular Degeneration (AMD) •Veterans Lutein Antioxidant Supplementation Trial (LAST)18 i.Evaluated the effects of daily lutein (10 mg); lutein (10 mg) plus a supplement containing additional carotenoids, antioxidants, vitamins and minerals; and placebo on central vision and macular pigment density over a 12-month period ii.Conducted among 90 people with AMD in the United States iii.Macular pigment density increased and visual function improved in people taking lutein or lutein plus the supplement; no changes occurred in people taking the placebo •Lutein Nutrition Effects Measured by Autofluorescence (LUNA)15 i.Evaluated the effects of a daily supplement (containing 12 mg lutein, 1 mg zeaxanthin, vitamin C, vitamin E, zinc, and selenium) on blood levels of lutein and zeaxanthin and macular pigment density over a 6-month period ii.Conducted among 136 people with and without AMD, aged 51-87 years, in Germany iii.Blood levels of lutein and zeaxanthin increased fourfold and macular pigment density increased significantly, compared to a control group not taking the supplement •Lutein Xanthophyll Eye Accumulation Study (LUXEA)16 i.Evaluated the effects of daily supplementation with 10.7 mg lutein, 12.6 mg zeaxanthin, a combination of 10 mg lutein plus 12 mg zeaxanthin, or a placebo on blood levels of lutein and zeaxanthin and macular pigment density over a 6-month period ii.Conducted among 92 healthy people, aged 18-45 years (study location not specified) iii.Blood levels of lutein increased 7-fold with the lutein only supplement; levels of zeaxanthin increased 27-fold with the zeaxanthin only supplement; levels of lutein increased 4-fold and levels of zeaxanthin increased 14-fold with the combination supplement iv.Macular pigment density increased 15% with lutein only, 14% with zeaxanthin only, and 15% with lutein plus zeaxanthin, compared with placebo •Short Term Antioxidant Supplementation32 i.Evaluated the effects of a daily antioxidant supplement (15 mg lutein, 20 mg vitamin E, and 18 mg niacin) versus no treatment on retinal function over a 6-12 month period ii.Conducted among 30 people with early AMD and 8 healthy controls in Italy iii.Compared to those receiving no treatment, people with early AMD and healthy people taking the supplement had beneficial changes in retinal function, as measured by focal electroretinogram iv.These changes suggest that increasing the antioxidant level in the retina may influence macular function early in the AMD process as well as in normal aging 2. Cataract •Lutein and Vitamin E Pilot Study33 i.Examined the effects of lutein (15 mg 3 times weekly), vitamin E (100 mg three times weekly), or placebo on blood levels and visual performance over a 2-year period ii.Conducted among 17 people with age-related cataracts in Spain iii.Visual performance (visual acuity and glare sensitivity) improved with lutein but not with vitamin E 3. Skin Health •Carotenoid Supplements and Sunburn34 i.Examined the effects of daily supplements of beta carotene (24 mg), a carotenoid mixture (8 mg beta-carotene, 8 mg lycopene, 8 mg lutein), or placebo on skin levels of carotenoids and sunburn over a 12-week period ii.Conducted among 36 healthy people in Germany iii.The carotenoid mixture increased the concentration of carotenoids in the skin and reduced the severity of sunburn following UV light exposure •Lutein and Zeaxanthin Supplements and Skin Health35 i.Examined the effects of oral and/or topical administration of lutein and zeaxanthin on skin health over a 12-week period ii.Conducted among 40 women with premature skin aging, aged 25-50 years, in Italy iii.Oral, topical, and combined oral and topical administration improved all skin parameters (surface lipids, elasticity, hydration, photoprotective activity, and skin lipid peroxidation) compared to placebo. The combined administration provided greater benefits than either oral or topical application alone. Are Lutein and Zeaxanthin Safe? Lutein and zeaxanthin occur naturally in fruits and vegetables and they are a normal component of a healthy diet. Dietary supplements containing lutein and/or zeaxanthin have been tested in clinical trials and no side effects or biochemical abnormalities have been reported: •Healthy volunteers took 4.1 mg or 20.5 mg lutein with zeaxanthin daily for 42 days; the supplement was well tolerated and there was no effect on concentrations of other carotenoids in blood14 •Elderly people with and without AMD took supplements of up to 10 mg daily for 6 months; no apparent toxicity or side effects were observed •People with AMD took 10 mg lutein daily for 12 months; minor side effects were no different in people taking lutein than in people taking placebo18 •People with age-related cataracts took 15 mg lutein three times weekly for up to 2 years; no side effects or changes in biochemical or blood profiles were found33 •Healthy volunteers took 1 mg or 10 mg synthetic zeaxanthin for 42 days; zeaxanthin was well tolerated, no side effects were reported, and there was no impact on blood levels of other carotenoids36 A review of the safety of lutein concluded that the evidence supports the safety of lutein at intakes up to 20 mg daily. The authors of the review state that much higher levels of lutein have been tested without adverse effects and may be safe, but conclude that the existing data are not sufficient to assess the long-term safety of lutein intakes higher than 20 mg per day.37 How Much Lutein and Zeaxanthin is Recommended? There is currently no recommended dietary allowance (RDA) for lutein, zeaxanthin, or other carotenoids. The recommendation for fruits and vegetables, the main sources of carotenoids in the diet, is at least 5 servings per day. However, surveys in the United States show that only about a third of people eat the minimum amount of fruits and vegetables and a large proportion of the population does not eat a single serving of fruit on any given day.3 The optimal intake of lutein and zeaxanthin for maintaining eye health and general health is not known. Typical daily intakes from food range from 0.8 to 2.2 mg.6, 19, 27, 38 However, research studies suggest that higher intakes of lutein and zeaxanthin are needed to protect against the development of AMD and cataracts: •5.3 mg was associated with greater macular pigment density26 •6 mg was associated with a lower risk of AMD22 •6.9 mg and 11.7 mg were associated with lower risks of cataract29, 30 •Supplements containing 10-15 mg were used in clinical trials that demonstrated increased macular pigment density and improved vision in people with AMD15, 18, 33 A new clinical trial sponsored by the National Institutes of Health, called the Age-Related Eye Disease Study II (AREDS II), is currently underway. AREDS II will test the effects of supplements containing 10 mg lutein, 2 mg zeaxanthin, and omega-3 fatty acids.39 PIVEG
PIVEG offers several advantages, including:•Complete control of the growing, harvesting, and processing, which results in consistent, high-quality carotenoid products •Highly stabilized, ester-free, purified natural carotenoids ensure high intestinal absorption without impacting the size of a capsule or tablet •Carotenoid ingredients are available to accommodate any nutraceutical form •Expert assistance in formulating and manufacturing products and creating custom products for clients •Flexibility in processing of carotenoids to meet client specifications and volume •High production volumes result in a year-round supply to meet customer needs PIVEG (Pigmentos Vegetales del Centro) is a fully integrated company specializing in purified carotenoids: Lutein, Zeaxanthin, Lycopene, Beta Carotene and Lutein Esters. PIVEG is the world leader in marigold production from seed to concentrate owning all the facilities in which its products are manufactured, with more than 40 years experience growing marigold. PIVEG is a global supplier of carotenoids to the food, nutraceutical, and pharmaceutical industries and holds certifications for GMP (Good Manufacturing Practices), HACCP (Hazard Analysis Critical Control Point), ISO 9001:200 and ISO 22000:2005 (International Organization for Standardization). PIVEG offers several advantages, including: •Complete control of the production process: seed production, growing, harvesting, processing, extraction, purification and encapsulation which results in consistent, high-quality carotenoid products. •Highly concentrated and stabilized, ester-free, purified natural carotenoids ensure high intestinal absorption without impacting the size of a capsule or tablet •Different formulations are available to accommodate any dosage form and any requirement •Expert assistance in formulating and manufacturing products and creating custom formulations for clients •Flexibility in processing of carotenoids to meet client specifications and volume •High production volumes result in a year-round supply to meet customer needs Conclusion
Lutein and zeaxanthin are natural dietary carotenoids that play important roles in eye health and general health. Observational research studies suggest that higher intakes of lutein and zeaxanthin from fruits and vegetables may protect against the development of AMD and cataracts. Clinical trials demonstrate that supplements containing lutein and zeaxanthin increase the concentration of these carotenoids in the blood and in the eyes, and that supplements may improve vision in people with AMD. Clinical trials also suggest that the antioxidant activity of lutein and zeaxanthin can help protect against skin damage caused by sunlight and aging.Age-related eye diseases dramatically decrease the quality of life and are a leading cause of disability. The number of people suffering from these eye diseases is expected to increase as the population ages. Current treatments for AMD are limited, and prevention may be the only way to reduce the personal and public health burden of the disease. Dietary supplements containing lutein and zeaxanthin are a safe and convenient way to increase the levels of these protective carotenoids in the body. References 1.Bartley GE, Scolnik PA. Plant carotenoids: pigments for photoprotection, visual attraction, and human health. Plant Cell. 1995;7:1027-1038. 2.Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press. 2000. 3.America’s Eating Habits: Changes and Consequences. US Department of Agriculture; May 1999. Agriculture Information Bulletin No. 750. Available at: http://www.ers.usda.gov/publications/aib750/aib750.pdf. 4.Krinsky NI, Landrum JT, Bone RA. Biologic mechanisms of the protective role of lutein and zeaxanthin in the eye. Annu Rev Nutr. 2003;23:171-201. 5.Whitehead AJ, Mares JA, Danis RP. Macular pigment. A review of current knowledge. Arch Ophthalmol. 2006;124:1038-1045. 6.Slattery ML, Benson J, Curtin K, Ma K-N, Schaeffer D, Potter JD. Carotenoids and colon cancer. Am J Clin Nutr. 2000;71:575-582. 7.Khachik F, de Moura FF, Chew EY, et al. The effect of lutein and zeaxanthin supplementation on metabolites of these carotenoids in the serum of persons aged 60 or older. Invest Ophthalmol Vis Sci. 2006;47:5234-5242. 8.Johnson EJ. Obesity, lutein metabolism, and age-related macular degeneration: a web of connections. Nutr Rev. 2005;63:9-15. 9.Age-related macular degeneration. National Eye Institute. Available at: http://www.nei.nih.gov/health/maculardegen/armd_facts.asp. Accessed August 31, 2007. 10.Macular degeneration. Mayo Clinic. Available at: http://www.mayoclinic.com/health/macular-degeneration/DS00284. Accessed August 31, 2007. 11.Soubrane G, Cruess A, Lotery A, et al. Burden and health care resource utilization in neovascular age-related macular degeneration. Findings of a multicountry study. Arch Ophthalmol. 2007;125:1249-1254. 12.Cataract. National Eye Institute. Available at: http://www.nei.nih.gov/health/cataract/cataract_facts.asp. Accessed August 31, 2007. 13.Sies H, Stahl W. Nutritional protection against skin damage from sunlight. Annu Rev Nutr. 2004:173-2000. 14.Thürmann PA, Schalch W, Aebischer J-C, Tenter U, Cohn W. Plasma kinetics of lutein, zeaxanthin, and 3-dehydro-lutein after multiple doses of a lutein supplement. Am J Clin Nutr. 2005;82:88-97. 15.Trieschmann M, Beatty S, Nolan JM, et al. Changes in macular pigment optical density and serum concentrations of its constituent carotenoids following supplemental lutein and zeaxanthin: the LUNA study. Exp Eye Res. 2007;84:718-728. 16.Schalch W, Cohn W, Barker, FM. Xanthophyll accumulation in the human retina during supplementation with lutein or zeaxanthin – the LUXEA (Lutein Xanthophyll Eye Accumulation) study. Arch Biochem Biophys. 2007;458:128-135. 17.Landrum JT, Bone RA, Joa H, Kilburn MD, Moore LL, Sprague KE. A one year study of the macular pigment: the effect of 140 days of a lutein supplement. Exp Eye Res. 1997;65:57-62. 18.Richer S, Stiles W, Statkute L, 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. 2007;75:216-230. 19.Burke J, Curran-Celentano J, Wenzel AJ. Diet and serum carotenoid concentrations affect macular pigment optical density in adults 45 years and older. J Nutr. 2005;135:1208-1214. 20.Stringham JM, Hammond BR. Dietary lutein and zeaxanthin: possible effects on visual function. Nutr Rev. 2005;63:59-64. 21.Eye Disease Case Control Study Group. Antioxidant status and neovascular age-related macular degeneration. Arch Ophthalmol. 1993;111:104-109. 22.Seddon JM, Ajani UA, Sperduto RD, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA. 1994;272:1413-1420. 23.VandenLangenberg GM, Mares-Perlman JA, Klein R, Klein BEK, Brady WE, Palta M. Associations between antioxidant and zinc intake and the 5-year incidence of early age-related maculopathy in the Beaver Dam Eye Study. Am J Epidemiol. 1998;148:204-214. 24.Mares-Perlman JA, Fisher AI, Klein R, et al. Lutein and zeaxanthin in the diet and serum and their relation to age-related maculopathy in the third National Health and Examination Survey. Am J Epidemiol. 2001;153:424-432. 25.Age-Related Eye Disease Study Research Group. The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study. AREDS Report No. 22. Arch Ophthalmol. 2007;125:1225-1232. 26.Mares JA, LaRowe TL, Snodderly DM, et al. Predictors of optical density of lutein and zeaxanthin in retinas of older women in the Carotenoids in Age-Related Eye Disease Study, an ancillary study of the Women’s Health Initiative. Am J Clin Nutr. 2006;84:1107-1122. 27.Moeller SM, Parekh N, Tinker L, et al. Associations between intermediate age-related macular degeneration and lutein and zeaxanthin in the Carotenoids in Age-Related Eye Disease Study (CAREDS). Ancillary study of the Women’s Health Initiative. Arch Ophthalmol. 2006;124:1151-1162. 28.Lyle BJ, Mares-Perlman JA, Klein BEK, Klein R, Greger JL. Antioxidant intake and incident age-related nuclear cataracts in the Beaver Dam Eye Study. Am J Epidemiol. 1999;149:801-809. 29.Chasan-Taber L, Willett WC, Seddon JM, et al. A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women. Am J Clin Nutr. 1999;70:509-516. 30.Brown L, Rimm EB, Seddon JM, et al. A prospective study of carotenoid intake and risk of cataract extraction in US men. Am J Clin Nutr. 1999;70:517-524. 31.Heinen MM, Hughes MC, Ibiebele TI, et al. Intake of antioxidant nutrients and the risk of skin cancer. Eur J Cancer. 2007;43:2707-2716. 32.Falsini B, Piccardi M, Iarossi G, Fadda A, Merendino E, Valentini P. Influence of short-term antioxidant supplementation on macular function in age-related maculopathy: a pilot study including electrophysiologic assessment. Ophthalmology. 2003;110:51-60. 33.Olmedilla B, Granado F, Blanco I, Vaquero M. Lutein, but not alpha-tocopherol, supplementation improves visual function in patients with age-related cataracts: a 2-y double-blind, placebo-controlled pilot study. Nutrition. 2003;19:21-24. 34.Heinrich U, Gartner C, Wiebusch M, et al. Supplementation with B-carotene or a similar amount of mixed carotenoids protects humans from UV-induced erythema. J. Nutr. 2003;133:98-101. 35.Palombo P, Fabrizi G, Ruocco V, et al. Beneficial long-term effects of combined oral/topical antioxidant treatment with the carotenoids lutein and zeaxanthin on human skin: a double-blind, placebo-controlled study. Skin Pharmacol Physiol. 2007;20:199-210. 36.Hartmann D, Thürmann PA, Spitzer V, Schalch W, Manner B, Cohn W. Plasma kinetics of zeaxanthin and 3’-dehydro-lutein after multiple oral doses of synthetic zeaxanthin. Am J Clin Nutr. 2004;79:410-417. 37.Shao A, Hathcock JN. Risk assessment for the carotenoids lutein and lycopene. Regul Toxicol Pharmacol. 2006;45:289-298. 38.Gruber M, Chappell R, Millen A, et al. Correlates of serum lutein and zeaxanthin: findings from the Third National Health and Nutrition Examination Survey. J Nutr. 2004;134:2387-2394. 39.Seddon J. Multivitamin-multimineral supplements and eye disease: age-related macular degeneration and cataract. Am J Clin Nutr. 2007;85(suppl):304S-307S. |
Keywords: LUTEIN STORY
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