This study was published in the American Journal of Clinical Nutrition 1999 Aug;70(2):247-51
Study title and authors:
Lutein and zeaxanthin concentrations in plasma after dietary supplementation with egg yolk.
Handelman GJ, Nightingale ZD, Lichtenstein AH, Schaefer EJ, Blumberg JB.
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA. Handelman_lp@hnrc.tufts.edu
This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/10426702
The lead researcher of the study, Dr Garry Handelman from Tufts University Boston, notes that lutein and zeaxanthin have been identified as carotenoids that accumulate in the macular region of the human retina that may play a role in the prevention of age-related macular degeneration and some forms of cancer.
The study sought to determine whether levels of lutein and zeaxanthin are elevated after consumption of egg yolks. The study included 11 men and women who firstly consumed diets without any egg yolks for 4.5 weeks, and secondly consumed similar diets with the addition of 1.3 egg yolks per day for another 4.5 weeks.
The study found:
(i) The diets containing egg yolks raised levels of lutein by 39% compared to the diets containing no egg yolks.
(ii) The diets containing egg yolks raised levels of zeaxanthin by 128% compared to the diets containing no egg yolks.
Dr Handelman concluded: "Egg yolk is a highly bioavailable source of lutein and zeaxanthin".