Published Oct 28, 2024 at 11:59 AM EDTPistachios may protect our eyes and brains from deteriorating as we age, according to new research from Tufts University, Massachusetts.

“Pistachios are a nutrient-dense snack that provide essential vitamins, minerals and antioxidants,” lead author of the study Professor Tammy M. Scott, from the Friedman School of Nutrition Science and Tufts University School of Medicine, told Newsweek.

“What’s particularly interesting is their unique content of lutein, a plant pigment that plays a crucial role in eye health. Lutein helps protect the eyes from damage caused by blue light and oxidative stress.

“This makes pistachios not just a tasty snack, but a functional food with specific health benefits.”

The Tufts scientists investigated lutein and its counterpart, zeaxanthin, which are antioxidants commonly found in dark green leafy vegetables such as spinach, as well as egg yolks and pistachios.

They found that eating two ounces of pistachios per day was linked to a significant increase in macular pigment optical density (MPOD), an important indicator of eye health.

MPOD protects the retina and is linked to a reduced risk of age-related macular degeneration (AMD), the leading cause of blindness in older adults.

“We chose to study pistachios because they are the only nut that contains significant amounts of lutein, a carotenoid known for its protective role in the eyes,” said Scott, explaining that lutein and zeaxanthin accumulate in the central part of the retina, where they filter harmful blue light and reduce wear and tear.

“Given that pistachios also contain healthy fats that aid nutrient absorption, we hypothesized that they could be an effective dietary strategy to increase [MPOD].”

To test this hypothesis, the scientists conducted a randomized controlled trial with 36 adults aged 40 to 70, who were healthy except for low lutein intakes.

The participants were randomly put into two groups, one of which continued to consume their usual diets, and the other added 2 ounces of pistachios per day. This is about two handfuls of pistachios, approximately doubling the participants’ intake of lutein.

Shelled pistachio nuts in a wooden spoon. Shelled pistachios are a tasty snack with real health benefits, says Professor Tammy Scott.PAVEL IARUNICHEV/Getty ImagesThe scientists measured their MPOD levels before the study, halfway through (six weeks) and at the end (12 weeks).

“The results were clear: those who ate pistachios experienced a significant increase in MPOD in as little as six weeks, which suggests that regular pistachio consumption could help maintain eye health be increasing lutein levels in the retina,” said Scott.

Lutein may also help brain health, by crossing from the blood into the brain and acting as an antioxidant, calming inflammation—a key risk factor for diseases such as dementia.

Previous studies have linked higher consumption of lutein with better cognitive performance in later life, including quicker memory and processing.

“We hope that people start to see pistachios as more than just a healthy snack,” said Scott. “Our findings suggest that pistachios could be a simple and natural way to support long-term eye health.  “This is especially important as we age and the risk of vision problems increases.”

Scott told Newsweek: “Personally, I love pistachios straight out of the shell!” and that she also enjoyed the nuts in salads, with yogurt and homemade granola, and in baked goods such as muffins.

This study was partially funded by American Pistachio Growers and the National Institutes of Health.

American Pistachio Growers is a non-profit trade association representing pistachio growers, processors and industry partners in Arizona, California, New Mexico and Texas.

This study was published in The Journal of Nutrition on October 18.