Lutein is selectively incorporated into the macula and brain. Lutein levels in the macula (macular pigment; MP) and the brain are related to better cognition. MP density (MPD) is a biomarker of brain lutein. Avocados are a bioavailable source of lutein. This study tests the effects of the intake of avocado on cognition. This was a six-month, randomized, controlled trial. Healthy subjects consumed one avocado (n = 20, 0.5 mg/day lutein, AV) vs. one potato or one cup of chickpeas (n = 20, 0 mg/day lutein, C). Serum lutein, MPD, and cognition were assessed at zero, three, and six months. Primary analyses were conducted according to intent-to-treat principles, with repeated-measures analysis. At six months, AV increased serum lutein levels by 25% from baseline (p = 0.001). C increased by 15% (p = 0.030). At six months, there was an increase in MPD from baseline in AV (p = 0.001) and no increase in C. For both groups, there was an improvement in memory and spatial working memory (p = 0.001; p = 0.032, respectively). For AV only there was improved sustained attention (p = 0.033), and the MPD increase was related to improved working memory and efficiency in approaching a problem (p = 0.036). Dietary recommendations including avocados may be an effective strategy for cognitive health.
Keywords: avocado; bioavailability; cognition; lutein; macular pigment; older adult.