Lutein is a naturally occurring vitamin belonging to the carotenoid family.1 It is best known for its deep yellow-green pigment.2 Like many complex nutrients, lutein is not manufactured in the human body so it must be consumed in foods.1

Because of its intense color, lutein is also considered a xanthophyll, from the Greek words for “yellow” and “leaf.”2 Similar to most carotenoids, lutein known for its potent antioxidative qualities.3 Cellular protection against oxidative damage is well established as an essential mechanism of many phytonutrients. Lutein, however, has a second, unique function in the way it protects cells from high-frequency blue light.3 


Background 


Shortly after the turn of the century, researchers discovered a specific photoreceptor in the retina that is very sensitive to the high-energy blue light that is the part of the light spectrum most damaging to cells, especially retinal cells.4 


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Scientists have long known that the central retinal cells (i.e., the macula) contain high concentrations of lutein.4 Research animals fed diets devoid of lutein quickly developed macular degeneration as well as cataracts.5 


Measurement of the optical density of affected macular cells showed both a decreased optical pigment density and a decreased lutein concentration. This has led to a search for a preventive intervention for these conditions. 


Science


Age-related macular degeneration (AMD) accounts for at least 45% of all vision loss in the Western world,6 equating to 9.1 million people, and by 2050 this will increase to an estimated 17.8 million.7 The total cost attributed to AMD in the United States alone is more than $700 billion.8

Numerous trials support the efficacy of lutein supplementation in the reduction or prevention of AMD, as well as other age-related conditions such as cataracts. 


However, as is the case with many herbal and nutritional supplements, conflicting reports are also found. One review of both interventional and observational studies found insufficient evidence to support lutein for AMD or cataract prevention,9 whereas a more recent review, showed evidence that lutein supplementation was efficacious for these degenerative eye diseases.10 


One research team followed 108 patients with known or suspected early AMD for 48 weeks.11 In this randomized, double-blind, placebo-controlled study, patients showed a significant dose-response effect when given lutein supplementation, with statistically significant improvements in macular pigment optical density (MPOD) and visual acuity.11

In a similar study, 27 patients with early AMD were followed for one year.12 Positive outcomes were noted in the lutein-supplementation group, specifically those relating to the density of macular pigmentation and visual acuity.12 


A subsequent trial involved 90 adult men with atrophic AMD studied for one year.6 Outcomes showed an increased MPOD and improved visual acuity in the treatment group.6 


In another extension study from the Women’s Health Initiative (WHI), women aged 50-79 years in three states were grouped into cohorts of either high intake or low intake of lutein and zeaxanthin.13 These women were evaluated for the incidence of nuclear cataracts from four to seven years post WHI. Women in the highest vs. lowest intake quintiles were found to be 32% less likely to develop cataracts.13 


Safety, interactions 


Lutein is safe for consumption. As a supplement, it is also generally recognized as safe by the FDA. Antioxidants (in very large doses) can interact with lutein, potentially causing GI distress and some elevation in warfarin (Coumadin, Jantoven) activity. 


Dose, how supplied, cost


Lutein is usually found in powder-filled capsules. The studies reviewed used an average 10-mg supplement per day in oral form. The cost is approximately $15 for a one-month supply. For those who would rather eat a lutein-enhanced natural diet, kale, spinach, turnip and collard greens all contain approximately 10 mg of lutein per serving. 


Summary


When consumed in recommended doses whether as a supplement or in natural form, lutein was associated with no significant adverse events. The potential long-range benefit of lutein intake is tremendous, especially in the case of AMD.

References


  1. Mozaffarieh M, Sacu S, Wedrich A. The role of the 
carotenoids, lutein and zeaxanthin, in protecting against age-related macular degeneration. Nutr J. 2003;2:20.

  2. Ribaya-Mercado JD, Blumberg JB. Lutein and zeaxanthin and their potential roles in disease prevention. J Am Coll Nutr. 2004;23(6 Suppl):567S-587S.
  3. Alves-Rodrigues A, Shao A. The science behind lutein. 
Toxicol Lett. 2004;150:57-83.

  4. Thompson CL, Bowes Rickman C, Shaw SJ, et al. Expression of the blue-light receptor cryptochrome in the human retina. Invest Ophthalmol Vis Sci. 2003;44:4515-4521. Available at 
http://www.ncbi.nlm.nih.gov/pubmed/14507900.

  5. Kijlstra A, Tian Y, Kelly ER, Berendschot TT. Lutein: more than just a filter for blue light. Prog Retin Eye Res. 2012;31:303-315.
  6. 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. 2004;75:216-230.

  7. Caban-Martinez AJ, Davila EP, Lam BL, et al. Age-related macular degeneration and smoking cessation advice by eye care providers: a pilot study. Prev Chronic Dis. 2011;8:A147. Available at www.ncbi.nlm.nih.gov/pmc/articles/PMC3221586/.

  8. BrightFocus Foundation. Macular Degeneration Facts & Statistics. Available at www.brightfocus.org/macular/about
/understanding/facts.html.
  9. Trumbo PR, Ellwood KC. Lutein and zeaxanthin intakes and risk of age-related macular degeneration and cataracts: an evaluation using the Food and Drug Administration’s evidence-based review system for health claims. Am J Clin Nutr. 2006;84:971-974. Available at ajcn.nutrition.org/content/84/5/971.long.

  10. Barker FM 2nd. Dietary supplementation: Effects on visual performance and occurrence of AMD and cataracts. Curr Med Res Opin. 2010;26:2011-2023.

  11. Ma L, Yan SF, Huang YM, et al. Effect of lutein and 
zeaxanthin on macular pigment and visual function in patients with early age-related macular degeneration. Ophthalmology. 2012;119:2290-2297.
  12. Parisi V, Tedeschi M, Gallinaro G, et al. Carotenoids and antioxidants in age-related maculopathy Italian study: multifocal electroretinogram modifications after 1 year. Ophthalmology. 2008;115:324-333.
  13. Moeller SM, Voland R, Tinker L, et al. Associations between age-related nuclear cataract and lutein and zeaxanthin in the diet and serum in the Carotenoids in Age-Related Eye Disease Study (CAREDS), an ancillary study of the Women’s Health Initiative. Arch Ophthalmol. 2008;126:354-364. Available at archopht.jamanetwork.com/article.aspx?articleid=484355.


All electronic documents accessed August 15, 2013.

From the September 01, 2013 Issue of Clinical Advisor

Topics:

Complementary and Alternative Medicine Diet and Nutrition Ophthalmology