Avocado Consumption Increases Neural Lutein and Improves Cognitive Function

Lutein, a dietary carotenoid, is selectively taken up into primate neural tissue such as the macula and brain. Lutein levels in serum, macula (macular pigment, MP) and brain are related to better cognition. MP is a biomarker of lutein levels in brain. Avocados are a highly bioavailable source of lutein. This 6 mo randomized, controlled trial tested the effects of daily intake of 1 medium avocado (AV, n=19) vs 1 medium potato or 1 cup of chickpeas (C, n=20) on serum lutein levels, MP density and cognition in healthy older adults (>50 yrs). Serum carotenoids were measured by HPLC. MP density, using heterochromatic flicker photometry, was used as a measure of lutein in neural tissue. A computerized cognitive assessment battery was used for cognition measures (CANTAB). At baseline there were no significant differences between the AV and C in any of the study measures. At 6 mo, serum lutein levels in the AV group significantly increased from baseline by 20% (34.7+11.2 to 41.8+14.3 pmol/dL, p <0.0005) whereas the C group increased by 7% (34.8+17.3 to 37.1+16.3 pmol/dL, p <0.03). At 6 mo there was a significant increase in MP density in the AV group (0.396+0.141 to 0.481+0.123 OD, p <0.001). MP density did not change from baseline in the C group (0.385+0.166 vs 0.424+0.145 OD). In the AV group the change in MP density was significantly related to an improved spatial working memory (p <0.009) and problem approaching efficiency (p <0.036). No significant changes in cognitive function were observed in the C group. These data suggest that an intervention with avocados to increase neural lutein is an effective dietary strategy for cognitive health. This study was supported by the Hass Avocado Board and USDA 58-1950-0-014