By: Jen Houchins, PhD
The dietary carotenoids lutein and zeaxanthin (yellow pigments) selectively accumulate in the retina of the eye and can be measured non-invasively with a test easily conducted outside the clinic. The result of this short visual assessment is reported as Macular Pigment Optical Density (MPOD), which can range from 0 to values over 1 log unit, with an average around ~0.35.1 MPOD measures the amount of lutein + zeaxanthin in the retina. Since these carotenoids cannot be synthesized by the human body, MPOD is a direct reflection of the habitual diet. Emerging science continues to link MPOD to eye and brain health across the lifespan, which is eggciting news for egg fans, as eggs are a bioavailable food source of lutein.
The accumulation of lutein in the fovea of the retina supports eye health likely though its ability to act as an antioxidant and anti-inflammatory agent, capacity to absorb damaging blue light (short wavelengths), and potentially by enhancing communication among neurons. As summarized in a recent presentation and new review paper, macular pigment is linked to visual function and is associated with reduced risk of age-related macular degeneration (AMD). MPOD been studied in relation to speed of visual processing, contrast sensitivity, the ability to recover visibility after a bright flash of light, and various other measures of visual function. The totality of the literature supports that dietary lutein is important for eye health across the lifespan. 1
Recent data also demonstrate that macular pigment is related to brain lutein levels, allowing MPOD to be used as a non-invasive biomarker in studies studying cognitive outcomes. 2,3 As previously shared, emerging data link MPOD to measures of math and written comprehension in preadolescent children and various studies connect lutein status to indicators of cognitive function in older adults. Overall, macular pigment appears to be a reliable biomarker of brain lutein concentration across the lifespan, and is potentially valuable for assessment of cognition. 1,4
Most Americans do not consume an adequate amount of lutein + zeaxanthin to increase MPOD, with an average intake ~1-2 mg/day, below the suggested 6 mg/day to maintain eye health. 5 However, the good news is that increasing dietary lutein through foods and/or supplements can increase MPOD in most people. 1, 6 Lutein can be found in a variety of foods, including green leafy and other vegetables such as broccoli, brussels sprouts, and avocados. A large egg provides 252 mcg lutein + zeaxanthin in a highly bioavailable form and egg consumption may help build macular pigment. One study in women between the ages of 24-59 found that eating 6 eggs/week increased MPOD over a 12-week period, with a larger increase observed in participants with lower baseline MPOD levels. 6
So regardless of your age, current research indicates that a habitual diet that includes various food sources of lutein can help support eye and brain health. Please explore our recipes to find new ways to prepare and eat eggs!
References
- Stringham, J.M., E.J. Johnson, and B.R. HAmmond, Lutein Across the Lifespan: from Childhood Cognitive Performance to the Aging Eye and Brain. Curr Dev Nutr, 2019.
- Vishwanathan, R., W. Schalch, and E.J. Johnson, Macular pigment carotenoids in the retina and occipital cortex are related in humans. Nutr Neurosci, 2016. 19(3): p. 95-101.
- Vishwanathan, R., et al., Macular lutein and zeaxanthin are related to brain lutein and zeaxanthin in primates. Nutr Neurosci, 2013. 16(1): p. 21-9.
- Wallace, T.C., A Comprehensive Review of Eggs, Choline, and Lutein on Cognition Across the Life-span. J Am Coll Nutr, 2018. 37(4): p. 269-285.
- Johnson, E.J., et al., Intake of lutein and zeaxanthin differ with age, sex, and ethnicity. J Am Diet Assoc, 2010. 110(9): p. 1357-62.
- Wenzel, A.J., et al., A 12-wk egg intervention increases serum zeaxanthin and macular pigment optical density in women. J Nutr, 2006. 136(10): p. 2568-73.