Egg yolks for eye health
|Lutein and zeaxanthin are found in egg yolks.|
This morning I spoke with a lady in a coffeeshop who told me she “heard on Dr. Oz” that she should be eating an egg a week for her eyes. I told her differently: she may need to eat them more often than once a week, turn to spinach, or supplement with lutein and zeaxanthin for her aging eyes. Now, because she said she’d get online and read this blog, I want to back my statements up.
In 2009, University of Massachusetts researchers (1) evaluated lutein and zeaxanthin from egg yolks on older adults with low macular pigment optical density, most whom were taking statins to lower cholesterol.* They found that eating four egg yolks per day, and possibly two egg yolks per day, improve macular health after five weeks. Notably, the treatments also increased HDL cholesterol, but not LDL cholesterol.
Previous studies showed lutein and zeaxanthin from spinach, corn or supplements (2 to 30 milligram doses) can also increase macular pigment optical density. However, one study (2) showed the bioavailability of lutein was higher from lutein-enriched eggs than from spinach or supplements.
Several clinical trials suggest low dietary intake of lutein and zeaxanthin contributes to age-related macular degeneration (AMD). Most recently, the ongoing Age-related Eye Disease Study-2 (AREDS2) (3) found that lutein supplementation increases macular pigment optical density and visual activity significantly after six months, which may potentially reduce risk of developing advanced AMD.
AREDS2 is a multi-center randomized trial, sponsored by the National Eye Institute, designed to evaluate high-doses of the xanthophyls and/or long-chain omega-3s (DHA and EPA) for treating AMD and cataracts. They study began in 2008 and will follow 4,000 participants for five and six years. Previously, AREDS1 showed antioxidant vitamins (500 milligrams of vitamin C; 400 International Units of vitamin E; 15 milligrams of beta-carotene) plus zinc (80 milligrams) and copper (2 milligrams) could reduce risk of developing advanced AMD by 25 percent!
What are lutein and zeaxanthin? Lutein and zeaxanthin are a pair of chemically identical, but structurally different natural yellow pigments found in plants like spinach, kale, and corn. Egg yolks also receive their characteristic yellow color from these pigments. Other well-known carotenoid pigments are beta-carotene (a pro-vitamin A carotenoid), alpha-carotene, and beta-cryptoxanthin (a pro-vitamin A carotenoid).
In the retina of the eye, lutein and zeaxanthin make up macular pigment to absorb and filter high-energy blue light, thereby protecting pigment epithelial cells beneath the macula against photo-oxidative damage. Photo-oxidative damage in the eye, specifically, is to blame for the onset of AMD, which becomes more prevalent in the U.S. as the population grows older.
AMD is the leading cause of vision loss in elderly and currently affects 30 to 50 million worldwide.
*Note: The Un. of Massachusetts study received support from the American Egg Board, the Egg Nutrition Center, and the Massachusetts Lions Research Fund Inc.
1. Vishwanathan R, Goodrow-Kotyla EF, Wooten BR, Wilson TA, Nicolosi RJ. Consumption of 2 and 4 egg yolks/d for 5 wk increases macular pigment concentrations in older adults with low macular pigment taking cholesterol-lowering statins. Am J Clin Nutr 2009;90:1272-9. doi: 10.3945/ajcn.2009.28013
2. Chung H, Rasmussen HM, Johnson EJ. Lutein Bioavailability Is Higher from Lutein-Enriched Eggs than from Supplements and Spinach in Men J Nutrition 2004;134(8):1887-1893.
3. Weigert G, Kaya S, Pemp B, Sacu S, Lasta M, Werkmeister RM, Dragostinoff N, Simader C, Garhöfer G, Schmidt-Erfurth U, Schmetterer L. Effects of lutein supplementation on macular pigment optical density and visual acuity in patients with age-related macular degeneration. Invest Ophthalmol Vis Sci 2011 Aug 27. [Epub ahead of print]