Dietary interventions with pistachios — a bioavailable source of the xanthophyll lutein — are efficacious in increasing macular pigment optical density (MPOD) in healthy adults, according to a new study from Tufts University and Tufts Medical Center.
Pistachios are the only nut that provides a measurable source of lutein, a powerful antioxidant that helps protect the eyes. Image credit: Erika Varga.
Lutein and zeaxanthin are dietary xanthophylls, a class of carotenoids most commonly found in vegetables and fruits, with green leafy vegetables being especially rich sources.
These compounds cross the blood brain barrier and exclusively accumulate in the macular region of the human retina where they are referred to as macular pigment.
Pistachios are the only nut that contain significant amounts of either lutein and zeaxanthin, but unlike eggs contain only lutein.
Similar to eggs, however, pistachios provide a source of fat, mainly as mono- and polyunsaturated fats, potentially making them a highly bioavailable source of lutein.
“Our findings indicate that pistachios are not only a nutritious snack, but they may also provide significant benefits for eye health,” said Dr. Tammy Scott, a research and clinical neuropsychologist at Tufts University.
“This is especially important as people age and face higher risks of vision impairment.”
The randomized controlled trial showed that compared to eating a usual diet alone, eating 2 ounces (57 grams) of pistachios per day for 12 weeks as part of a usual diet resulted in a significant increase in MPOD in otherwise healthy middle-aged to older adults.
They also found that pistachio consumption nearly doubled participants’ daily intake of lutein and significantly raised its plasma levels.
“By simply incorporating a handful of pistachios into your diet, you can improve your intake of lutein, which is crucial for protecting your eyes,” Dr. Scott said.
“Pistachios provide a source of healthy fat, potentially making the lutein from pistachios better taken up into the body.”
“About 1.6 mg of lutein was provided from pistachios, which would be enough to double the average daily consumption of lutein, which is in a class of plant pigments known as xanthophylls, in U.S. adults.”
Beyond supporting eye health, lutein found in pistachios may also benefit brain function.
“Lutein crosses the blood-brain barrier, where it may help reduce oxidative stress and inflammation,” said Dr. Elizabeth Johnson, a researcher at Tufts University.
“As with the eye, lutein selectively accumulates in the brain and may play a role in reducing cognitive decline.”
“Studies suggest higher lutein levels are associated with better cognitive performance, including memory and processing speed, making pistachios a valuable addition to a diet aimed at supporting overall healthy aging.”
The study was published on October 17, 2024 in the Journal of Nutrition.
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Tammy M. Scott et al. Pistachio consumption increases Macular Pigment Optical Density in healthy adults: a randomized controlled trial. Journal of Nutrition, published online October 17, 2024; doi: 10.1016/j.tjnut.2024.10.022
