Adding 57 g of pistachios daily for 12 weeks to a diet increased macular pigment optical density (MPOD) due to the plant pigment lutein found in the nuts. MPOD is an important indicator of eye health. It protects the retina from blue or visible light and is linked to a reduced risk of age-related macular degeneration (AMD), a leading cause of blindness in older adults. 

In the single-blinded, randomized controlled trial, researchers from the Friedman School of Nutrition Science and Policy at Tufts University, US, seleced 36 middle-aged to older healthy participants with low MPOD and low intake of lutein and zeaxanthin, plant pigments that impact MPOD. One group consumed a “usual diet,” while the other added 57 g of pistachios to their daily diet. 

“Our findings indicate that pistachios are not only a nutritious snack, but they may also provide significant benefits for eye health,” highlights Dr. Tammy Scott, a research and clinical neuropsychologist and lead author of the study. “This is especially important as people age and face higher risks of vision impairment.”

The American Pistachio Growers and the US National Institutes of Health funded the study.

Lutein benefits

For the study, published in The Journal of Nutrition, researchers measured participants’ MPOD and blood lutein levels at baseline, six and 12 weeks. After six weeks, the pistachio group saw a “significant rise in MPOD,” sustained throughout the three-month study. 

According to the researchers, pistachios are the “only nut that provides a measurable source of lutein.” The pigment acts as an antioxidant in the eye and helps filter blue light. 

The pistachio group nearly doubled their daily intake of lutein, which is typically very low in the diets of US adults. The pistachios provided around 1.6 mg of lutein, sufficient to double the average daily consumption of the compound. The nuts also significantly raised plasma levels of lutein in this group. 

“By simply incorporating a handful of pistachios into your diet, you can improve your intake of lutein, which is crucial for protecting your eyes,” underscores Scott. In addition, she notes that pistachios provide a source of healthy fat, which potentially helps absorption of the lutein from pistachios.

Moreover, lutein in pistachios may also benefit brain function. Dr. Elizabeth Johnson, a co-investigator in the study, explains: “Lutein crosses the blood-brain barrier, wher it may help reduce oxidative stress and inflammation.” 

The compound accumulates in the brain and may support reducing cognitive decline. Studies indicate that higher lutein levels are linked to better mental performance, such as memory and processing speed. 

Eye health supplements

Consumer demand for products that help maintain eye health grows with rising screen time and age-related eye concerns. Innova Market Insights data indicates a 7% annual growth in product launches with eye health claims between 2018 and 2022. 

Earlier this year, researchers found that supplementing kids with lutein and zeaxanthin isomers improved their visual and cognitive performance. Meanwhile, Kemin calls to add these compounds to standard-of-care prenatal vitamins to improve eye health in pregnant mothers and their babies.

At the same time, the International Nut and Dried Fruit Council highlighted that long-term mixed nut consumption improves brain insulin sensitivity in a study of overweight or obese older adults. The researchers note that mixed nut consumption may be important for preventing age-related metabolic and cognitive diseases.