Pistachios: Eye Health, Lutein and Zeaxanthin

Table of Contents

1. The Macula and Its Yellow Pigment
2. Why Lutein and Zeaxanthin Collect There
3. How Macular Pigment Is Measured
4. How Much Lutein Pistachios Contain
5. Lutein, Not Zeaxanthin
6. Why the Fat Matters for Absorption
7. The Pistachio Macular Pigment Trial
8. Blood Lutein in the Same Trial
9. How the Result Compares With Spinach, Eggs and Supplements
10. The Wider Picture: AREDS2 and Diet Studies
11. What Is Not Known
12. Who the Research Raises Concerns For
13. Connections
14. Key Research Papers
15. Featured Videos

The Macula and Its Yellow Pigment

The retina is the light-sensing layer that lines the back of the eye. Near its centre is the macula, an area only a few millimetres across that is packed with the cone cells used for reading, recognising faces, driving and seeing fine detail and colour. At the very middle of the macula is a small pit, the fovea, where vision is sharpest. Peripheral vision — seeing movement out of the corner of the eye — is handled by the rest of the retina.

The macula has a yellow tint. That colour is the macular pigment, made of three carotenoids: lutein, zeaxanthin and meso-zeaxanthin, a form the body makes from lutein. Carotenoids are the family of yellow, orange and red plant pigments that also includes beta-carotene. Lutein and zeaxanthin belong to a sub-group called xanthophylls. People cannot make them; every molecule in the eye comes from food or supplements.

The review by Eisenhauer and colleagues (2017) notes that about 700 carotenoids have been described in nature and roughly 20 to 30 have been identified in human blood and tissues, but only lutein and zeaxanthin (with meso-zeaxanthin) are found in the eye. Inside the macula the three are not evenly spread: meso-zeaxanthin dominates at the very centre, zeaxanthin in the middle ring, and lutein towards the outer edge of the macula.

The macula matters because it is where age-related macular degeneration (AMD) happens. AMD slowly damages central vision while side vision is spared, and it is described in the same review as one of the leading causes of blindness in older adults in the developed world.

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Why Lutein and Zeaxanthin Collect There

The research describes two jobs for the macular pigment. Both follow from where it sits — in front of the light-sensing cells, in the part of the retina that receives the most focused light.

• A blue-light filter. Lutein and zeaxanthin absorb light at the blue, short-wavelength end of the visible spectrum. Blue light carries more energy per particle of light than red or green light, and the trial authors describe the macular pigment as a blue-light filter that prevents photochemical (light-driven chemical) damage to the photoreceptors beneath it. A layer of yellow pigment in front of the cones soaks up some of it before it reaches them, the way yellow-tinted lenses cut blue glare. The Eisenhauer review adds that filtering blue light also reduces chromatic aberration — the slight blur caused by blue light focusing at a different point from other colours — which may sharpen visual acuity and contrast.
• An antioxidant. Light and oxygen together can produce reactive oxygen molecules (“free radicals”) able to damage cells. The trial authors describe the pigment as potentially preventing oxidative damage to the retina through its antioxidant properties. The authors of the pistachio trial summarise the current view: as macular pigment, lutein and zeaxanthin “are believed to provide protection from light damage as antioxidants and blue light filters.”

The word “believed” is doing real work. The Eisenhauer review describes these antioxidant and blue-light-filtering properties as hypothesised to protect the eye against AMD, and states that the precise roles and mechanisms are not fully understood. The review also reports that most studies have found macular pigment falls with age and tends to be low in people with AMD, which is part of why researchers became interested in whether raising it might help.

The site's zeaxanthin and blue-light protection and lutein and macular health pages cover the pigment's biology in more depth.

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How Macular Pigment Is Measured

Macular pigment can be measured in a living eye without any injection or blood test. The result is called macular pigment optical density (MPOD): a number describing how much blue light the pigment absorbs. The Eisenhauer review describes MPOD as linearly related to the amount of lutein and zeaxanthin in the macula, and notes that MPOD is used as a stand-in for macular health and to predict the likelihood of developing AMD.

The pistachio trial used a method called heterochromatic flicker photometry. The person looks at a small light that flickers between blue (which the pigment absorbs) and green (which it does not) and adjusts the brightness until the flicker seems to disappear. The more pigment there is, the brighter the blue has to be to match. The test was repeated at four distances from the centre of the macula, called eccentricities and measured in degrees of visual angle: 0.25°, 0.50°, 1.00° and 1.75°. The smallest number is closest to the centre, where the pigment is densest; 1.75° is towards the edge.

One point runs through the rest of this page: MPOD is a biomarker, not an eye-disease outcome. A higher reading shows more pigment is present. It does not, by itself, show that a person is less likely to develop macular degeneration or any other eye disease. That would need a trial counting cases of disease over years, and none has been run with pistachios.

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How Much Lutein Pistachios Contain

The USDA FoodData Central database reports lutein and zeaxanthin together as a single figure, because the two molecules are almost identical in structure and many lab methods do not separate them. The table uses the SR Legacy entries, per 100 grams and converted to a one-ounce (28.35 g) portion. Fat is shown because it bears on absorption (see below).

The USDA has no lutein value for raw macadamias.

What the table shows:

• Pistachios stand apart from other nuts. Per ounce, raw pistachios carry roughly 30 times the lutein and zeaxanthin of hazelnuts, the next nut on the list, and the other common nuts have almost none. Reviews of pistachio composition say the same thing in words: among nuts, pistachios have the highest levels of xanthophyll carotenoids (Dreher, 2012; Bulló and colleagues, 2015; Terzo and colleagues, 2019). Dreher's review adds that the kernel's green and purple colour comes from its lutein and anthocyanin content, and Mandalari and colleagues (2021) list carotenoids among the nut's bioactive compounds.
• Leafy greens carry far more. Gram for gram, raw spinach has about four times the lutein and zeaxanthin of raw pistachios, and kale about twice as much. The Eisenhauer review lists cooked kale at 18,246 mcg per 100 g. A pistachio is a modest source by the standards of a salad, but an unusual one for a nut.
• Published figures for pistachios vary a lot. The two USDA pistachio entries differ more than twofold (2,903 mcg raw against 1,160 mcg roasted). These are separate laboratory samples, so the gap cannot be read as a measured effect of roasting alone. The food table in the Eisenhauer review, drawn from an earlier USDA release, gives raw pistachios 1,404 mcg per 100 g. The trial described below calculated 1.65 mg (1,650 mcg) in a 57 g serving of roasted pistachios, which works out to roughly 2,900 mcg per 100 g. Carotenoid content in any plant depends on variety, growing conditions, ripeness, storage and processing.

For the rest of the nut's composition, see the pistachio nutrient profile; for food sources of lutein in general, see lutein sources and absorption.

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Lutein, Not Zeaxanthin

Because the USDA combines the two pigments, a reader could assume pistachios supply both. Laboratory measurements that separate them say otherwise. The Eisenhauer review reproduces a table of foods analysed for each pigment on its own: raw pistachios contained 1,405 mcg of all-trans lutein per 100 g and no measurable zeaxanthin. Spinach, kale, romaine lettuce and broccoli in the same table were also lutein-only. Eggs and corn contained both, in roughly equal amounts; orange pepper was mostly zeaxanthin.

The pistachio trial authors make the same point, describing pistachios as the only nut with significant amounts of either pigment but noting that, unlike eggs, they contain only lutein. As the next sections show, the blood results of the trial matched this: blood lutein rose and blood zeaxanthin did not. The body converts some lutein into meso-zeaxanthin in the macula, but dietary zeaxanthin itself comes from other foods.

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Why the Fat Matters for Absorption

Lutein and zeaxanthin dissolve in fat, not water. In the gut they have to be released from the food, dissolved into droplets of fat, packaged with bile into tiny particles called micelles, and taken up by the cells lining the small intestine. A meal with almost no fat gives them little to travel in.

The Eisenhauer review summarises studies showing that eating fat — a salad dressing, a cooking oil such as extra virgin olive oil, or whole eggs — in the same meal as carotenoid-rich vegetables increases the absorption of some carotenoids. It also reports that the lutein and zeaxanthin in eggs appear more bioavailable than those in vegetables even though eggs contain less, most likely because of the egg's fat. The pistachio trial authors cite earlier work finding that lutein and zeaxanthin in spinach or a supplement were about three times less bioavailable than in egg yolk.

This is the reason researchers became interested in pistachios specifically. A pistachio kernel is about 45 percent fat by weight (USDA), mostly mono- and polyunsaturated, so its lutein arrives already packaged with the fat needed to absorb it. The trial authors described this as “potentially making them a highly bioavailable source of lutein.” The same principle is behind the site's avocado and carotenoid absorption article, which reports a trial in which adding avocado to salsa or salad raised carotenoid absorption from the vegetables.

One caution on the logic: the trial did not compare pistachios with a low-fat lutein source at the same dose, so the role of the fat in its result is a plausible explanation the authors offer, not something the trial tested.

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The Pistachio Macular Pigment Trial

The only randomised trial in the research behind this page that measured macular pigment after eating pistachios was run at Tufts University in Boston and published by Scott and colleagues in the Journal of Nutrition in 2025 (registered as NCT05283941). The details below come from the published paper.

Who took part

• 36 healthy, non-smoking adults aged 40 to 70, recruited from the community. The average age was 59.5 years; 58 percent were women.
• People were chosen because they ate little lutein and zeaxanthin (2 mg a day or less; the average was 1.1 mg a day) and had low macular pigment to begin with (0.55 or below at the 0.50° position).
• Excluded were people with high cholesterol, liver, kidney or pancreatic disease, fat malabsorption, bowel disease, tree nut allergy, a BMI below 20 or above 36.9, or anyone who had taken lutein, zeaxanthin or omega-3 supplements in the previous two months.

What they ate

• Half (18) were randomly assigned to eat 2 ounces (57 g) of shelled, roasted, unsalted pistachios a day for 12 weeks on top of their usual diet. The study calculated this serving at 320 calories, 12 g protein, 26 g fat, 6 g fibre and 1.65 mg lutein/zeaxanthin.
• The other half (18) kept their usual diet and ate no pistachios.
• The pistachio group was asked to keep other lutein foods, such as leafy greens and eggs, at their usual levels. Most participants reported eating all of their pistachios; none reported less than 90 percent.
• The staff who measured macular pigment and blood levels did not know who was in which group (a single-blind design). Participants obviously knew whether they were eating pistachios, and there was no placebo food.

What happened to macular pigment

Macular pigment was measured at the start, at 6 weeks and at 12 weeks. In the pistachio group it rose significantly at all four positions by week 6 and stayed at that level at week 12, with no further significant rise between weeks 6 and 12. In the usual-diet group it did not change significantly. The difference between the groups over time was statistically significant at every position (P < 0.001). Body weight did not change significantly in either group.

Values are mean macular pigment optical density (intent-to-treat analysis, Table 3 of the paper). Three people did not attend the final visit; their week-6 values were carried forward, and an analysis of completers only gave similar results.

The authors concluded that pistachios were “efficacious in increasing MPOD in healthy adults selected for habitually low intake of L/Z and low baseline MPOD,” and wrote that future studies need to test whether the finding applies to other groups of people.

Limitations the authors listed

• Single-blind, with no true placebo.
• Blood cholesterol and lipoproteins were not measured, although these carry lutein in the blood.
• The 2-ounce dose is larger than the 1.5 ounces of nuts a day named in the FDA’s qualified health claim for tree nuts, as the authors note; a lower dose was not tested.
• Only middle-aged and older healthy adults with low intake and low pigment were studied, so it is unclear whether people with normal or high pigment would see a similar change.

Funding: the trial was supported by a US pistachio growers’ trade association, which also supplied the pistachios, and by a grant from the US National Institutes of Health. The paper states that the trade association had no role in the design, conduct or interpretation of the study, and the lead author disclosed the industry support.

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Blood Lutein in the Same Trial

Fasting blood samples were taken at the start and at week 12. The results line up with the composition data above.

• Lutein rose in the pistachio group, from an average of 18.71 to 27.82 micrograms per decilitre among those who completed the study, while it stayed flat in the usual-diet group (22.36 to 21.98). The difference between groups over time was significant (P = 0.021).
• Zeaxanthin did not change in either group (pistachio group 5.01 to 4.80), consistent with pistachios containing lutein but no zeaxanthin.
• Cis-lutein, a slightly different shape of the lutein molecule, did not change significantly either.
• The blood rise tracked the eye rise. People whose blood lutein went up more also tended to show bigger increases in macular pigment, at all four positions (correlation coefficients from 0.43 to 0.65).

The rise in blood lutein also served as a check that participants were eating their pistachios. Dietary questionnaires showed the pistachio group's lutein and zeaxanthin intake went up by about 1.33 mg a day, close to the 1.65 mg in the daily ration.

Earlier feeding studies have measured blood lutein after pistachio diets; they are not among the records checked for this page, and a PubMed search for them is linked under Key Research Papers.

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How the Result Compares With Spinach, Eggs and Supplements

In their discussion, the trial authors set their result beside earlier studies. These comparisons come from different trials with different people and methods, so they are rough, and they are the authors' own comparisons, not a head-to-head test.

• A 12 mg lutein/zeaxanthin supplement taken daily for four months by older healthy adults in an earlier study by the same group raised macular pigment by 0.041 at 0.40°. Pistachios raised it by 0.212 at the similar 0.50° position.
• 2 ounces of cooked spinach a day, containing about 11 mg of lutein/zeaxanthin, raised macular pigment by 0.15 at 1.00° over 12 weeks. Pistachios, with about 1.6 mg, raised it by 0.199 at the same position.
• One egg a day, containing about 0.33 mg, raised it by about 0.10 at 1.00° over 12 weeks.

The authors suggested two reasons a small lutein dose might go a long way: the fat in pistachios aiding absorption, and possibly pistachios' effect on blood fats. Lutein travels in the blood mainly on HDL particles, and HDL is involved in delivering it to nerve tissue such as the retina. A meta-analysis of 12 randomised trials (Hadi and colleagues) found pistachio consumption lowered total cholesterol, LDL cholesterol and triglycerides, while HDL did not change significantly; the trial authors speculated that this shift could redistribute lutein towards HDL. They did not measure blood lipids, and they called this an idea for future studies.

They also noted a ceiling effect seen in other food studies: macular pigment rose within about four to six weeks and then levelled off, as it did here.

The difference in starting points also matters. The pistachio trial chose people with low pigment and low intake. A group starting low has more room to rise, which may partly explain the size of the change compared with studies of more typical participants.

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The Wider Picture: AREDS2 and Diet Studies

Interest in lutein and the eye comes mostly from research on macular degeneration that had nothing to do with pistachios. The Eisenhauer review summarises it:

• AREDS and AREDS2. The original Age-Related Eye Disease Study tested a high-dose supplement of vitamins C and E, beta-carotene, zinc and copper and found it reduced the risk of progression to advanced AMD by about 25 percent. AREDS2, a five-year US trial in 4,203 adults aged 50 to 85 at risk of progressing to late AMD, added lutein (10 mg) and zeaxanthin (2 mg). In a secondary analysis, adding lutein and zeaxanthin to the AREDS supplement lowered progression to advanced AMD only in people who had the lowest lutein and zeaxanthin intake from food. The review states that the findings suggest lutein and zeaxanthin are likely more appropriate and safer than beta-carotene in AREDS-type supplements.
• Observational studies. Cohort and case-control studies, which compare what people already eat, have generally linked higher dietary lutein and zeaxanthin with lower odds of AMD. In data pooled from two large population studies in Australia and the Netherlands, the highest third of intake was associated with more than 20 percent lower risk of early AMD among people at high genetic risk, with no similar association in people at low genetic risk.
• Intake levels. The review notes that 6 mg a day of lutein and zeaxanthin has been suggested as a dietary target, based on a 1994 study, while cohort data suggest lower intakes of around 2.5 mg a day may be associated with some protection. It cites estimates that American adults eat roughly 1 to 2 mg of lutein a day. Its example meal plans for reaching 5 and 10 mg a day include pistachios alongside leafy greens and eggs; a 30 g serving of pistachios on porridge appears in one example.

None of these studies tested pistachios. AREDS2 tested purified supplements in people already at risk of advanced disease, and observational studies cannot prove cause and effect. They explain why macular pigment is studied, not what pistachios do to eye disease. More detail is on the macular degeneration and zeaxanthin and macular health pages.

Research has also looked at lutein and zeaxanthin in relation to cataracts; that literature is not reviewed here (a PubMed search is linked below). The pistachio trial did not examine the lens, and no pistachio study of cataracts appears in the research behind this page.

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What Is Not Known

• Whether pistachios change eye-disease risk. No trial has tested pistachios against macular degeneration, cataracts or any other eye-disease outcome. The trial authors themselves note that a specific link between pistachio intake and AMD prevention has not been evaluated. Higher macular pigment is a biomarker; it is not proof of less eye disease.
• Whether vision improved. The trial measured pigment and blood lutein, not eyesight. It did not test visual acuity, contrast sensitivity or glare recovery.
• Who else would respond. Only 36 middle-aged and older healthy adults, chosen for low intake and low pigment, took part. People with normal pigment, younger people, smokers, or people who already have AMD were not studied.
• The smallest dose that works. Only 2 ounces a day was tested. Whether 1 ounce does anything measurable is unknown.
• How long the change lasts. The trial ran 12 weeks and did not follow people after they stopped eating pistachios.
• Replication. This is a single trial, supported in part by industry funding. No independent repeat appears in the research behind this page.
• The role of the fat. The idea that pistachio fat explains the result is plausible but was not tested directly.
• Roasting and storage. USDA figures for raw and roasted pistachios differ more than twofold, but they come from separate samples. How processing and storage affect pistachio lutein is not settled by these data.

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Who the Research Raises Concerns For

• People with tree nut allergy. The review by Costa and colleagues (2019) describes pistachio as able to trigger moderate to severe allergic reactions, lists five officially recognised pistachio allergens, and notes that pistachio allergy is closely linked to cashew allergy. People with tree nut allergy were excluded from the macular pigment trial.
• Calories. The trial's 2-ounce daily serving supplied about 320 calories. Body weight did not change in the 12 weeks of the trial, which added the pistachios to people's usual diets. The weight trials are covered on the weight and mindful eating page.
• Salt. The trial used unsalted pistachios. Salted pistachios carry whatever sodium was added in processing.
• People with eye disease. The trial enrolled only healthy adults. Decisions about eye supplements or the management of macular degeneration belong with an eye doctor.

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Connections

• Nuts — the nuts landing page
• Pistachios — the main topic page
• Pistachios — Benefits Deep Dive — the hub for this series
• Pistachios: Nutrient Profile — the full composition table
• Protein and Fiber
• Cholesterol and Lipids
• Blood Pressure and Blood Vessels
• Blood Sugar and Diabetes
• Gut Microbiome
• Weight and Mindful Eating
• Lutein — the pigment pistachios supply
• Zeaxanthin — the partner pigment pistachios lack
• Lutein: Eye and Macular Health
• Lutein: Sources and Absorption
• Carotenoids — the pigment family
• Macular Degeneration — the disease behind macular-pigment research
• Cataracts
• Ophthalmology — the eye-disease section
• Spinach — the richest common lutein source
• Kale
• Eggs — a fat-rich source of both pigments
• Avocado and Carotenoid Absorption

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Key Research Papers

1. Scott TM, Ogunbodede O, McKay DL, et al. Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial. The Journal of Nutrition. 2025;155(1):168-174. PubMed PMID: 39426460
2. Eisenhauer B, Natoli S, Liew G, et al. Lutein and Zeaxanthin-Food Sources, Bioavailability and Dietary Variety in Age-Related Macular Degeneration Protection. Nutrients. 2017;9(2). PubMed PMID: 28208784
3. Dreher ML. Pistachio nuts: composition and potential health benefits. Nutrition Reviews. 2012;70(4):234-40. PubMed PMID: 22458696
4. Bulló M, Juanola-Falgarona M, Hernández-Alonso P, et al. Nutrition attributes and health effects of pistachio nuts. The British Journal of Nutrition. 2015;113 Suppl 2:S79-93. PubMed PMID: 26148925
5. Terzo S, Baldassano S, Caldara GF, et al. Health benefits of pistachios consumption. Natural Product Research. 2019;33(5):715-726. PubMed PMID: 29241364
6. Mandalari G, Barreca D, Gervasi T, et al. Pistachio Nuts (Pistacia vera L.): Production, Nutrients, Bioactives and Novel Health Effects. Plants (Basel). 2021;11(1). PubMed PMID: 35009022
7. Hadi A, Asbaghi O, Kazemi M, et al. Consumption of pistachio nuts positively affects lipid profiles: A systematic review and meta-analysis of randomized controlled trials. Critical Reviews in Food Science and Nutrition. 2023;63(21):5358-5371. PubMed PMID: 34933637
8. Costa J, Silva I, Vicente AA, et al. Pistachio nut allergy: An updated overview. Critical Reviews in Food Science and Nutrition. 2019;59(4):546-562. PubMed PMID: 28925724

Full text of the trial, including the macular pigment and blood tables quoted above: PMC11795683. Full text of the Eisenhauer review: PMC5331551. Food composition values: USDA FoodData Central.

PubMed Topic Searches

1. PubMed: pistachios, lutein and macular pigment
2. PubMed: pistachio diets and blood lutein / carotenoids
3. PubMed: AREDS2, lutein and zeaxanthin
4. PubMed: macular pigment optical density and diet trials
5. PubMed: lutein bioavailability and dietary fat
6. PubMed: lutein, zeaxanthin and cataract

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