Epidemiological studies suggest that consumption of lutein-rich foods may be of benefit in promoting cognitive health. Among the carotenoids, lutein and it isomer, zeaxanthin, are the only 2 that cross the blood-retina barrier to form macular pigment (MP) in the retina. Lutein also preferentially accumulates in the human brain across multiple life stages. Lutein concentrations in the retina of both human and nonhuman primates are significantly correlated with their levels in matched brain tissues, allowing for the use of MP density, which can be measured noninvasively in humans, as a biomarker of lutein in the brain. This has important implications for intervention studies involving lutein given that MP density, such as brain lutein, has been reported to be significantly related to cognitive function in adults. Although less is known about infants, cross-sectional studies have shown that breast milk lutein content enriches lutein in brain tissue and is related to infant recognition memory scores. Intervention studies in adults indicate that lutein may positively affect cognitive performance, and this effect may be influenced by the omega-3 fatty acid, docosahexaenoic acid. Although lutein is not an essential nutrient, efforts may be warranted to establish age-specific recommended intakes for this dietary bioactive for promotion of cognitive health.