Avocado Consumption Increases Macular Pigment Density in Older Adults: A Randomized, Controlled Trial

Randomized Controlled Trial

Tammy M Scott et al. Nutrients. 2017.

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, 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.

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Conflict of interest statement

Funding for this study was provided by the Hass Avocado Board. The funder did not have a role in the study design, interpretation, or manuscript preparation.

References

1. Bone R.A., Landrum J.T., Tarsis S.L. Preliminary identification of the human macular pigment. Vis. Res. 1985;25:1531–1535. doi: 10.1016/0042-6989(85)90123-3. - DOI - PubMed
1. Johnson E.J. A role for lutein and zeaxanthin in visual and cognitive function throughout the lifespan. Nutr. Rev. 2014;72:605–612. doi: 10.1111/nure.12133. - DOI - PubMed
1. Wang W., Connor S.L., Johnson E.J., Klein M.L., Hughes S., Connor W.E. Effect of dietary lutein and zeaxanthin on plasma carotenoids and their transport in lipoproteins in age-related macular degeneration. Am. J. Clin. Nutr. 2007;85:762–769. - PubMed
1. Renzi L.M., Hammond B.R., Jr., Dengler M., Roberts R. The relation between serum lipids and lutein and zeaxanthin in the serum and retina: Results from cross-sectional, case-control and case study designs. Lipids Health Dis. 2012;11 doi: 10.1186/1476-511X-11-33. - DOI - PMC - PubMed
1. Connor W.E., Duell P.B., Kean R., Wang Y. The prime role of HDL to transport lutein into the retina: Evidence from HDL-deficient WHAM chicks having a mutant ABCA1 transporter. Investig. Ophthalmol. Vis. Sci. 2007;48:4226–4231. doi: 10.1167/iovs.06-1275. - DOI - PubMed

Avocado Consumption Increases Macular Pigment Density in Older Adults: A Randomized, Controlled Trial - PubMed