BOSTON (Reuters Health) – Regular egg yolk consumption may reduce the risk of dry, age-related macular degeneration by raising macular pigment concentrations, according to a report in the November issue of the American Journal of Clinical Nutrition.
The study subjects were all older adults who were taking statins, and their low-density-lipoprotein cholesterol levels were unaffected even when they ate as many as four yolks per day.
“Two eggs per day is probably all that is needed to maximize blood levels of lutein and zeaxanthin as well as macular pigment optic density (MPOD) status,” senior author Dr. Robert J. Nicolosi from the University of Massachusetts in Lowell told Reuters Health by email.
The 5-month study had 4 phases. As Dr.Nicolosi and his coauthors explain, a 4-week baseline phase was followed by a 5-week 2 yolks/day phase, then a 4-week washout phase, and finally a 5-week 4 yolks/day phase.
In the 52 participants (mean age, 69 years), serum lutein increased by an average of 16% after the 2-yolk phase and 24% after the 4-yolk phase compared to baseline, and serum zeaxanthin increased from baseline by 36% and 82% after the 2- and 4-yolk phases, respectively.
Macular pigment optic density increased significantly after both regimens (more so after the 4-yolk phase), but only among individuals with low baseline density values.
Serum HDL-cholesterol increased during both phases of the study, the researchers note, but there were no significant changes from baseline in total cholesterol, low-density-lipoprotein cholesterol, or triglyceride levels.
“We are presently evaluating the effect of consuming 12 eggs/week for 1 year on the progression of dry age-related macular degeneration” in subjects with early- to mid-stage disease, the investigators write.
“Although this was only a 5-week study and the 1-year data are not ready for comment, it would seem to me that physicians could consider that those patients on statins, who have early stage age-related macular degeneration, could be prescribed 2 egg yolks per day,” Dr.Nicolosi said.
He added, “Our evidence and those of others indicate that increases in blood levels of lutein and zeaxanthin and MPOD correlate well with risk for age-related macular degeneration. So the egg yolk appears to enhance the bioavailability of nutrients that have been shown to reduce the risk of age-related macular degeneration, and at 2 egg yolks per day for individuals on statins, does not raise LDL and significantly raises HDL.”