Macular degeneration, the leading cause of vision loss in people over 60, is caused by loss of pigmentation in the macula, an area of the retina that processes central vision. Lutein, a member of the carotenoid family of vitamins, helps prevent macular degeneration by maintaining the pigmentation of the macula. Recent studies have shown that lutein in egg yolks is highly absorbable and effective at preventing macular degeneration.
Lutein
Egg yolks provide high levels of lutein, according to a study published in the November 2010 "European Journal of Clinical Nutrition." In the study, omega-3 fatty acid-enriched eggs and organic eggs were found to be even more effective at raising lutein levels than regular eggs. In the study, participants ate six organic or omega-3 fatty acid-enriched eggs per week for eight weeks. Blood levels of lutein were significantly higher for both egg groups than a control group. However, no difference in blood levels of lutein was noted between the two egg groups. The researchers noted that, while lutein is abundant in dark green leafy vegetables and some fruits, the lutein in eggs is more readily absorbed, making eggs an attractive food source for scientists to improve upon as a functional food in the prevention of macular degeneration.
Lutein and Zeaxanthin
Lutein and zeaxanthin -- another valuable member of the carotenoid family known to protect the macula from light damage -- improved pigmentation of the macula by as much as 50 percent in a study published in the November 2009 "American Journal of Clinical Nutrition." In the study on the benefits of eggs for macular degeneration, participants ate two egg yolks per day for five weeks, followed by four weeks with no eggs and then four egg yolks per day for another five weeks. Of note, blood levels of HDL -- the good cholesterol -- increased by 5 percent at the end of the study period, but levels of LDL -- the bad cholesterol -- were not affected by the egg consumption.
Cholesterol
A study published in the October 2006 "Journal of Nutrition" reported a 26 percent increase in blood levels of lutein and a 38 percent increase in blood levels of zeaxanthin from egg consumption in older adults. In the study, participants, all over 60 years of age, ate one egg per day for five weeks. Total cholesterol, LDL cholesterol and HDL cholesterol were not affected by the egg consumption, say the researchers.
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Enriched Eggs
Eggs can be successfully enriched with extra lutein by supplementing chicken feed, according to a study published in the October 2004 "Poultry Science" journal. Of note, when laying hens were fed experimental diets that contained flax along with supplemental lutein, lutein content in the eggs dropped, while a diet that contained alfalfa resulted in increased lutein content.
References
- "European Journal of clinical Nutrition"; Effect of N-3 Fatty Acid Enriched Eggs and Organic Eggs on Serum Lutein in Free-Living Lacto-Ovo Vegetarians; B.L. Burns-Whitmore; et al.; 2010
- "American Journal of Clinical Nutrition"; Consumption of Two and Four Egg Yolks/D for 5 Wk Increases Macular Pigment Concentrations in Older Adults With Low Macular Pigment Taking Cholesterol-Lowering Statins; R. Vishwanathan, et al.; 2009
- "Journal of Nutrition"; Consumption of One Egg Per Day Increases Serum Lutein and Zeaxanthin Concentrations in Older Adults Without Altering Serum Lipid and Lipoprotein Cholesterol Concentrations; E.F. Goodrow, et al.; 2006
- "Poultry Science"; Enrichment of Eggs With Lutein; S. Leeson, et al.; 2004
