Avocado consumption increases macular pigment density in older adults: a randomized, controlled trial

Authors: SCOTT, TAMMY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; RASMUSSEN, HELEN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; CHEN, CHUNG-YEN (OLIV - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; JOHNSON, ELIZEBETH - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2017
Publication Date: 8/23/2017
Citation: Scott, T., Rasmussen, H., Chen, C.E., Johnson, E.J. 2017. Avocado consumption increases macular pigment density in older adults: a randomized, controlled trial. Nutrients. 9(9). https://doi.org/10.3390/nu9090919.
DOI: https://doi.org/10.3390/nu9090919

Interpretive Summary: Lutein is selectively taken up into the macula of the retina and brain. Lutein levels in the macula (macular pigment; MP) and the brain are related to better cognition. Measures of MP density (MPD) is an indicator of levels of lutein in the brain. Lutein contained in avocados is well absorbed from the gut into the bloodstream. This study tests the effects of the intake of avocado on cognition. This was a six-month study. Healthy subjects consumed one avocado (containing lutein) or one potato or one cup of chickpeas (containing no lutein). Blood lutein, MPD and cognition were measured at zero, three, and six months. At six months, both the avocado and the control group had increased blood lutein levels. At six months (end of study), there was an improvement in memory for both groups. There were a few cognitive tests for which consumption of avocados demonstrated modest improvement. These results suggest that avocados may have some benefits for memory and cognition, but these would need to be confirmed in more studies because the group that did not consume avocados also demonstrated cognitive benefits.

Technical Abstract: 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, on 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 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 MOD 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.