Higher intake of carotenoid-rich vegetables and fruits has been consistently identified as a characteristic of healthy eating patterns. Lutein and zeaxanthin are carotenoids (lipid-soluble pigments) found abundantly in various vegetables such as spinach, kale, squash, peas, and are also present in egg yolks. These yellow carotenoids are selectively taken up by macular tissue of the retina and new research links these pigments to eye health as well as cognition1.
In the eye, lutein and zeaxanthin act as antioxidants and light filters, absorbing blue light before it reaches the macula and vision receptors. The accumulation of lutein and zeaxanthin in the macula is reported as macular pigment optical density (MPOD) and can be measured with a non-invasive assessment. MPOD is a direct reflection of lutein in the neural tissue, and as such, is used as a reliable indicator of brain lutein levels. In infants, the observations that lutein is preferentially taken up by the developing brain suggest a critical role in neural development. Emerging data link MPOD to measures math and written comprehension in children and studies are underway to further evaluate the relationship to cognitive function2.
A recent study in U.S. children aged 7-13 years examined the relationship between MPOD and measures of cognitive function. The researchers hypothesized that macular pigment would be beneficially associated with performance on standardized cognitive assessments. In this sample of 51 children, macular pigment was related to improved measures of cognitive function on select tests (intellectual ability and executive processes), supporting the hypothesis that lutein is linked to brain health and cognition3. Importantly, this study was not designed to evaluate cause-and-effect, so more research is needed regarding the specific role of lutein, but these data support the idea that habitual dietary habits could impact brain health in children, adolescents, and across the lifespan.
At the Egg Nutrition Center, we are particularly interested in this area of emerging research because of the unique nutrient package provided by eggs. Although eggs provide a lower amount of lutein + zeaxanthin compared to vegetables (252 mcg/large egg, as compared to over 20,000 mcg/cup canned spinach, for example), there is evidence that the lutein in eggs is more bioavailable4, meaning it is in a form that is readily absorbed and used in the body. Eggs additionally provide high-quality protein, a variety of B-vitamins required for the production of energy, and are one of the most concentrated food sources of choline in the American diet, a shortfall nutrient essential for brain health. This unique nutrient profile, combined with the exciting story that continues to unfold with lutein, might give you a few more reasons to recommend eggs as an important part of healthy dietary patterns for all ages.
- Johnson, E.J., Role of lutein and zeaxanthin in visual and cognitive function throughout the lifespan. Nutr Rev, 2014. 72(9): p. 605-12.
- 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.
- Saint, S.E., et al., The Macular Carotenoids are Associated with Cognitive Function in Preadolescent Children. Nutrients, 2018. 10(2).
- Chung, H.Y., H.M. Rasmussen, and E.J. Johnson, Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men. J Nutr, 2004. 134(8): p. 1887-93.