Consuming pistachios may increase macular pigment optical density in healthy adults with low lutein and zeaxanthin intake. This randomized controlled trial of 36 participants compared daily consumption of 2 oz of pistachios with a usual diet over 12 weeks.

In their pre-proof, published in The Journal of Nutrition, the researchers explained that pistachios contain large amounts of lutein, and because these nuts are a source of mono- and polyunsaturated fats, this lutein is highly bioavailable.

Indeed, they found that serum lutein increased notably in the pistachio group, reflecting improved bioavailability. Pistachio consumption also significantly boosted macular pigment optical density (MPOD) at all retinal eccentricities. The researchers noted that MPOD has been inversely associated with AMD incidence, and intake of significant amounts of lutein increases MPOD which can protect against AMD. It functions as a blue light filter which protects from damage to the photoreceptors. The researchers noted that approximately 6mg/d of lutein and zeaxanthin was associated with a lower risk for AMD.

Compliance to the pistachio diet was high, and no adverse effects were observed. Previous reports of a ceiling effect were also supported in this study, and the researchers noted that this likely means that MPOD can be increased by targeted changes in diet.

"While we can't draw formal conclusions from this very small study, and certainly cannot extrapolate the results to have clinical significance in the treatment or management of AMD, this is certainly interesting," commented Priya Vakharia, MD, of Retina Vitreous Associates of Florida, on the findings.

A full list of author disclosures can be found in the published pre-proof of this research.