Vishwanathan from the University of Massachusetts Lowell and co-authors have published a paper in the American Journal of Clinical Nutrition, investigating whether the regular consumption of egg yolks can prevent the development of age-related macular degeneration, a common cause of loss of sight in the elderly.

The authors explain that lutein and zeaxanthin may reduce the risk of dry, age-related macular degeneration because of their photo-oxidative role as macular pigment.

Their study evaluated serum lutein, zeaxanthin, and macular pigment optical density (MPOD) responses at 0.25º, 0.5º and 1º retinal eccentricities to the consumption of two and four egg yolks daily by older adults taking cholesterol-lowering medications.

Subjects consumed foods containing two followed by four egg yolks per day for five weeks, each with a four-week egg-free period at baseline and between the two interventions.

Results

Vishwanathan and co-authors found that changes in MPOD (n=37) with egg yolk consumption were inversely associated (P<0.05) with baseline MPOD.

Subjects with low-baseline MPOD (defined as MPOD 0.5 at 0.25°, 0.4 at 0.5°, and 0.35 at 1°) showed increases of 50 per cent (P<0.05) with four egg yolks at the three retinal eccentricities. MPOD increased by 31 per cent (P=0.059) at 0.5° with two egg yolks.

Serum lutein increased by only 16 per cent and 24 per cent (P<0.05) compared with increases of 36 per cent and 82 per cent (P<0.001) in serum zeaxanthin (n=52) after consumption of two and four egg yolks, respectively.

Serum HDL cholesterol increased by five per cent (P<0.05) after consumption of two and four egg yolks. Serum LDL cholesterol did not change with either egg yolk treatment.

Conclusions

The researchers conclude that the consumption of four egg yolks daily – and possibly of two egg yolks daily – for five weeks benefited macular health in older adults with low MPOD. Serum HDL cholesterol increased without an increase in LDL cholesterol in this study population, most of whom were taking cholesterol-lowering statins.

Reference

Vishwanathan R., E.F. Goodrow-Kotyla, B.R. Wooten, T.A. Wilson and R.J. Nicolosi. 2009 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. American Journal of Clinical Nutrition, 90 (5): 1272-1279 doi:10.3945/ajcn.2009.28013

Further Reading

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You can view the full report (fee payable) by clicking here.