Lutein and zeaxanthin are carotenoids which are deposited in the macula and protect against Age Related Macular Degeneration.
This 18 week study consisted of Phases 1 and 3 of 4 week duration where subjects refrained from eating eggs. Phases 2 and 4 of 5 week duration consisted of consuming the daily equivalent of 2 and 4 egg yolks, respectively with a 4 week washout period in between. Serum lutein concentrations in both phase 2 and 4 increased by 25% (p<0.001) compared to washout (n = 26). Serum zeaxanthin levels increased by 26.7% (p=0.019) following phase 2 and by 63.7% (p<0.001) following phase 4 compared to washout (n = 26).
HDL was also analyzed for lutein and zeaxanthin and was found to contain approximately 60% of the total amount of each carotenoid. MPOD which was measured using heterochromatic flicker photometry increased by 26.5% in subjects following phase 2 and by 30% (p=0.039) following phase 4 compared to washout at 0.25º retinal eccentricity (n = 26).
Preliminary results indicate that increasing the intake of zeaxanthin through egg yolk consumption significantly increases its blood levels, whereas with lutein, a plateau effect was observed even after consumption of 4 egg yolks per day for 5 weeks. Egg yolk consumption also increased the macular pigment density.
Goodrow E, Nicolosi R, Vishwanathan R, Wilson T (2007) Consumption of Menus Containing the Equivalent of Two and Four Egg Yolks in Older Adults on Cholesterol Lowering Medication is Associated with Significant Changes in Serum Lutein and Zeaxanthin Concentrations and Macular Pigment Optical Density (MPOD). The Journal of the Federation of Experimental Biology, 21:847.2