Pistachio nuts and eye pigment density in healthy adults
What it found
Eating 2 oz of pistachios daily for 12 weeks increased protective pigment levels in the eyes of healthy adults.
Blood levels of lutein also rose.
What they found
Studies in people
Eye pigment density increased
After 6 weeks, people eating pistachios had higher pigment density across all tested areas of the retina compared to those on their usual diet. This increase held steady through week 12. The usual diet group saw no change over the 12 weeks.
Blood lutein levels rose
Blood levels of lutein went up in the pistachio group by week 12, matching the rise seen in the eyes. Levels stayed the same in the usual diet group. Other related pigments did not change in either group.
Body weight unchanged
Weight did not change significantly in either group during the 12 weeks.
What the authors conclude
- They conclude that eating 2 oz of pistachios daily effectively raised protective eye pigment in adults who usually consume little lutein.
- They suggest adding pistachios to the diet could be a useful strategy for supporting eye health.
- They advise future research to test whether these results apply to other groups of people and to explore different serving sizes.
How it was done
Lutein is a plant pigment that builds up in the back of the eye to help protect it from light damage. Pistachios are the only nut with notable amounts of lutein, so the authors wanted to see if eating them could raise eye pigment levels.
The researchers recruited 36 healthy adults aged 40 to 70 who normally ate very little lutein. Half were randomly assigned to eat 2 oz (57 g) of roasted, unsalted pistachios every day for 12 weeks, while the other half kept their usual diet. Eye pigment density was measured at the start, at 6 weeks, and at 12 weeks.
What it can’t tell you
- This trial only included adults who already had low lutein intake and low eye pigment at the start. It cannot show whether people with normal or high levels would see the same changes.
- The study lasted 12 weeks, so it cannot show what happens to eye pigment over many years of eating pistachios.
Who paid
- Funding
- Funded by NCATS NIH HHS (from the PubMed record).
- Conflicts
- Conflict of interest Tammy M Scott reports financial support provided by American Pistachio Growers. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
- Authors work at
- Tufts University, United States; Tufts Medical Center, United States
The paper
- Title
- Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Scott TM, Ogunbodede O, McKay DL, Johnson EJ (2025). Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial. The Journal of nutrition. doi:10.1016/j.tjnut.2024.10.022Free full textPubMed 39426460DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error