Zeaxanthin

Zeaxanthin is a yellow-orange pigment from the carotenoid family, the same family as beta-carotene and lutein. It is a xanthophyll, a carotenoid that carries oxygen. Plants and algae make it. In yellow sweet corn it is, with lutein, one of the two main pigments that give the kernels their color.

People and other animals cannot make it, so it has to come from food.

Plants use it as a safety valve. In strong light, leaf cells turn another pigment, violaxanthin, into zeaxanthin, which helps them shed light energy they cannot use. In one alga the first steps took 15 seconds.

Your eyes use it too. The center of the retina, the macula, is yellow because of three carotenoids: lutein, zeaxanthin and meso-zeaxanthin. At the very center, zeaxanthin leads.

In donor eyes the lutein to zeaxanthin ratio averaged about 1 to 2.4 there. Yet a typical diet holds about five times more lutein than zeaxanthin.

Here is the part most people do not know. Dark green leafy vegetables, the usual advice for eye health, are rich in lutein. But in one analysis, only 0 to 3% of their carotenoids were zeaxanthin.

The same analysis found orange pepper had the most zeaxanthin of the vegetables tested, and corn and egg yolk are mostly lutein plus zeaxanthin. The third macular carotenoid, meso-zeaxanthin, is rare in food, and the eye appears to make it from lutein.

Health benefits of zeaxanthin

• ★★Supplements raised pigment density in the eyeIn 20 trials, supplements of lutein, zeaxanthin and meso-zeaxanthin raised eye pigment density by 0.07 in people with macular degeneration and 0.09 in healthy people. It measures the eye, not vision.
• ★★No clear slowing of late macular degenerationIn the AREDS2 trial (4,203 people), 10 mg of lutein plus 2 mg of zeaxanthin did not clearly slow advanced disease (0.90 times the risk). A Cochrane review found little or no difference too.
• ★★Slightly sharper vision in macular degenerationIn 8 trials of 1,176 people with macular degeneration, lutein plus zeaxanthin supplements improved sharpness a little (0.04 logMAR) and contrast vision, compared with placebo.
• ★★No fewer cataract operations overallIn 3,159 people in AREDS2, lutein plus zeaxanthin did not reduce cataract surgery overall (0.96 times as likely). In people with the lowest diet intake it was 0.68 times, a subgroup result.
• ★Zeaxanthin alone gave mixed pigment resultsIn 60 older people with early macular degeneration, 8 mg of zeaxanthin a day raised eye pigment, but no better than lutein. In 22 healthy people, 10 mg did not raise it, while lutein did.

Foods high in zeaxanthin

The NutriScrolls ranking below comes from USDA data, which measures lutein and zeaxanthin together as one number. So it cannot show how much of each a food has. Dark green leafy vegetables rank high. But in one analysis they held 15 to 47% of their carotenoids as lutein and only 0 to 3% as zeaxanthin.

Where zeaxanthin itself stands out, the papers point to orange pepper, corn, egg yolk and goji berries. Orange pepper had 37% of its carotenoids as zeaxanthin, the highest of the vegetables tested. In corn and egg yolk, lutein plus zeaxanthin made up more than 85% of the carotenoids. Yellow and orange chili peppers were also among the best pepper sources.

Amounts are small in everyday foods. Fresh yellow sweet corn holds about 0.2 to 0.3 mg of zeaxanthin per 100 g. So the 2 mg in the AREDS2 supplement would take about 670 to 1,000 g of kernels. A sweet corn bred for zeaxanthin reached more than 2.0 mg per 100 g.

Dried goji berries held 1,143.7 µg of zeaxanthin dipalmitate per gram, about 114 mg per 100 g, as the form the berry makes. They held only 1.4 µg per gram as free zeaxanthin. Meso-zeaxanthin turns up in few foods, such as shrimp shell and fish skin.

How zeaxanthin works

Most of what we know about how zeaxanthin works comes from donor eyes, test tubes, plants and animals, not from people taking pills. Researchers keep coming back to four ideas. It gathers at the center of the macula, and the eye makes a twin of it there. It filters blue light, and in plants it helps leaves shed excess light.

Here is each one, plus how it sits in a membrane and what has been seen in people.

It gathers at the center of the macula

The macula is the small part of the retina that sees fine detail. Xanthophylls pile up there at about 1 mM. A 2020 review says zeaxanthin is about 2.5 times more concentrated than lutein in the cone-dense center.

In donor eyes, the lutein to zeaxanthin ratio averaged about 1 to 2.4 in the central 0.25 mm. At the far edge it was over 2 to 1.

In about 90% of 87 donors aged 3 to 95, zeaxanthin was the main pigment. The authors tied the change to the ratio of rods to cones, and suggested that cones take up zeaxanthin and rods take up lutein. That is a proposal, not a proven mechanism.

It has a twin that the eye makes itself

A third pigment sits at the very center. Meso-zeaxanthin has the same atoms as zeaxanthin but a different arrangement at one end. It does not occur in plants and has no common dietary source. In cultured cells, and in chicken eye tissue, an enzyme called RPE65 turned lutein into meso-zeaxanthin by shifting a double bond.

In a 1997 study of donor eyes, infant retinas had less meso-zeaxanthin, relative to zeaxanthin, than adult ones. That fits the idea that the eye makes it over time. A 2013 review adds a caution: the story that retinal meso-zeaxanthin comes only from lutein needs another look. Eating zeaxanthin did not produce it in a 12-person trial.

It filters blue light

Macular pigment absorbs blue light before it reaches the light-sensing cells behind it. In a 2007 trial it was measured at 460 nm, in the blue range. A 2003 review says this may protect the cells from damage started by reactive oxygen.

Monkeys give some support. Normal monkeys had a fovea that was less sensitive to blue-light damage than the area beside it. Monkeys raised without xanthophylls lost that protection, and pure lutein or pure zeaxanthin brought it back. In quail, more zeaxanthin in the retina went with fewer dying rods and cones. Still, the 2003 review says a causal link has not been shown by experiment.

Filtering may not explain everything people notice. In a 59-person trial, higher pigment went with better contrast sensitivity and more sensitive edge detection. The authors point out that a filter would dim light and dark bars the same, so they suggest the nerve cells themselves are involved.

It lets plants shed excess light

Zeaxanthin is a working part of every green leaf. In strong light, an enzyme turns violaxanthin into antheraxanthin and then zeaxanthin, and in darkness the pigment returns to violaxanthin. A review of photosystem II says zeaxanthin is the major player in calming excited chlorophyll, which is how plants shed excess energy. It also works as an antioxidant in the membrane.

Lutein, by comparison, mostly calms a different excited form of chlorophyll. In the alga Chlorella, cells held in the zeaxanthin state resisted flash damage better than cells in the violaxanthin state. Making zeaxanthin was a prerequisite for the protection.

Plants that cannot make zeaxanthin pay for it. An Arabidopsis mutant without the enzyme suffered in strong light, above 500 µmol of light per square meter per second. Its mature leaves showed oxidative stress and chlorophyll loss. It also had lipid damage when singlet oxygen was generated. Young leaves of the same mutant coped, with extra vitamin E.

And the cycle is not one fixed speed: its pool size and pace vary by species and environment. In the alga Heterosigma akashiwo, antheraxanthin and zeaxanthin appeared within 15 seconds of strong light, while in Platymonas only antheraxanthin did.

It lies across cell membranes

Zeaxanthin has a hydroxyl group at each end, which makes it polar (water-loving) and suits it to spanning a membrane. How it sits depends on the test. A 1999 study of lipid layers found that zeaxanthin stood roughly upright, while lutein split into two groups.

A 2017 study with microscopy and computer simulation found that both lutein and zeaxanthin tilt about 40 degrees. That is because the membrane is thinner than the molecule is long. In the 1999 tests, both pigments slowed fat damage by free radicals about equally. Zeaxanthin was better during long UV exposure, because lutein itself broke down.

What has been seen in people

These ideas are easier to show in a dish than in a person. In people, supplements do raise macular pigment, but only by small amounts: 0.07 to 0.09 density units in the meta-analysis above. Whether that protects the macula is less certain.

The main AREDS2 result was not clear (0.90 times the risk), and the 18% lower risk against beta-carotene came from exploratory analyses. Zeaxanthin alone raised pigment in one trial of older people with early macular degeneration and in goji berry users with high myopia. But it did not in healthy volunteers who took 10 mg of it. All of these are among the study cards above.

Is zeaxanthin safe? Supplements, dose and interactions

Zeaxanthin from food is not a safety concern in the sources we read. A typical diet gives about 1 to 3 mg of lutein a day, with roughly five times less zeaxanthin than lutein.

For synthetic zeaxanthin in supplements, EFSA, the European food safety agency, reached a conclusion in 2012. Intakes of 0.75 mg per kg of body weight a day do not raise safety concerns. That is 53 mg for a 70 kg adult.

EFSA took a no-effect dose from a rat study (150 mg/kg a day) and divided it by 200, because no long-term study existed. The applicant had asked for use up to 2 mg a day.

In the US, the FDA had no questions about a marigold-derived zeaxanthin extract at up to 300 µg per serving of food. That was GRAS notice 639 (Kemin, 2016).

• Trial doses and side effects. The AREDS2 supplement held 2 mg of zeaxanthin with 10 mg of lutein. One trial gave 8 mg of zeaxanthin a day for a year with no adverse effects reported. EFSA lists studies at up to 20 mg a day for up to 6 months without adverse effects.
• A rare eye finding. In 8 people with macular telangiectasia, one patient on 20 mg a day developed yellowish crystals in the macula, with no change in acuity. They disappeared several months after the dose was stopped. We did not see this in other trials.
• Smokers and lung cancer. Beta-carotene raised lung cancer in AREDS2 (1.82 times the odds at 10 years). Lutein and zeaxanthin did not clearly do so (1.15). EFSA considers a risk from zeaxanthin unlikely but notes that no human or animal data exist.
• Eye disease, pregnancy and drugs. The AREDS2 formulas were tested with vitamins and zinc. So ask an eye doctor before swapping or adding supplements for macular degeneration. We found no drug interactions and no pregnancy or breastfeeding data in the sources, so ask your doctor.

How to get more zeaxanthin

• Best foods. Look past the greens: orange pepper, corn and egg yolk were the standouts. Six eggs a week for 12 weeks raised serum zeaxanthin and macular pigment in women. Yellow sweet corn gives only 0.2 to 0.3 mg per 100 g.
• Egg yolk absorbs well. A review suggests the xanthophylls in egg yolk may be more easily absorbed than those in other foods. In a test-tube digestion model, the type of fat barely changed how much lutein and zeaxanthin could be absorbed, unlike beta-carotene and lycopene.
• Cooking and storage. In a digestion model, tortilla gave the most absorbable zeaxanthin of three maize foods (18.5%), and boiled kernels the least absorbable carotenoids. Goji berries stored for 28 days lost about 80% of their zeaxanthin dipalmitate in one lab study, at both room and hot, humid conditions.

History of zeaxanthin

The story of zeaxanthin is mostly the story of the macula. In 1985, researchers tentatively identified the human macular pigment as lutein and zeaxanthin by comparing chromatograms of retinal extracts with standards.

In 1988 a second group measured the pigments in the whole retina. They found that zeaxanthin was concentrated in the macular region, while lutein was spread through the entire retina. The same year, a donor-eye study showed how the lutein to zeaxanthin ratio shifts across the retina. It went from 1 to 2.4 at the center to over 2 to 1 at the edge.

In 1997 the donor-eye work added a puzzle. Meso-zeaxanthin, a form not found in the diet, was present in the macula, and the authors proposed that the eye makes it from lutein. In 2017 a team showed that the enzyme RPE65 can do that conversion in chicken tissue and in cultured cells.

Meanwhile the regulators moved too. In 2008 EFSA said the safety of synthetic zeaxanthin at up to 20 mg a day in supplements had not been established. After a rat reproduction study arrived, its 2012 statement found no safety concern at the levels the applicant proposed. In 2013 the AREDS2 trial tested 2 mg of zeaxanthin with 10 mg of lutein in 4,203 people.

Frequently asked questions about zeaxanthin

What does zeaxanthin do for the body?

It builds up in the macula, where it helps filter blue light. Supplements raise the density of macular pigment, as a meta-analysis of 20 trials found. Whether that protects sight is less clear. In AREDS2, 2 mg of zeaxanthin with 10 mg of lutein did not clearly lower progression to advanced macular degeneration (0.90 times the risk). Most studies tested zeaxanthin together with lutein, so its own effect is hard to separate.

Which foods are high in zeaxanthin?

Orange pepper, corn, egg yolk and goji berries stand out in the papers we read. Orange pepper had the highest share of zeaxanthin (37% of carotenoids) among the vegetables tested. Fresh yellow sweet corn holds only about 0.2 to 0.3 mg per 100 g. Dark green leafy vegetables are rich in lutein but held 0 to 3% of their carotenoids as zeaxanthin.

How much zeaxanthin should you take a day?

No dose is proven best. AREDS2 used 2 mg of zeaxanthin with 10 mg of lutein, and single trials used 8 mg, 10 mg and up to 20 mg. EFSA found that 53 mg a day of synthetic zeaxanthin for a 70 kg adult does not raise safety concerns. But the applicant asked only for up to 2 mg. Ask a clinician before going higher.

Does zeaxanthin have side effects?

Trials reported few. EFSA lists studies at up to 20 mg a day for up to 6 months without adverse effects. One patient with macular telangiectasia on 20 mg developed yellowish crystals in the macula that faded after stopping. We found no drug interactions or pregnancy data in the sources, so ask your doctor.

Is zeaxanthin better than lutein?

No study here shows a clear winner. In the diet, lutein outweighs zeaxanthin about five to one, but at the center of the macula zeaxanthin leads. Lutein raised macular pigment more than zeaxanthin in 22 healthy volunteers (10 mg each). The two raised it about equally in older people with early macular degeneration. And a goji berry dose with 20 mg of zeaxanthin beat 2 mg of lutein in people with high myopia. Most supplements and trials give both.

What is meso-zeaxanthin, and do you need it?

Meso-zeaxanthin is a form of zeaxanthin found at the very center of the macula. It is rare in food, and the eye appears to make it from lutein. Formulas with it raised macular pigment at more distances in small trials. But adding 10 mg to the AREDS2 formula made no difference to vision in a trial of 121 people. Nothing here shows you need it.

Does zeaxanthin help with macular degeneration or cataracts?

Possibly, but the trials are not convincing. In cohort studies, diets high in lutein and zeaxanthin went with 26% lower risk of late macular degeneration and 25% lower risk of nuclear cataract. These studies cannot prove cause. In AREDS2, lutein and zeaxanthin did not clearly lower either macular degeneration progression or cataract surgery overall.

Are goji berries a good source of zeaxanthin?

They are a rich source, mostly as zeaxanthin dipalmitate: 1,143.7 µg per gram of dried fruit in one analysis. In 12 people, that ester reached the blood better than free zeaxanthin. A goji milk product raised plasma zeaxanthin by 26% in older adults. Stored berries lost about 80% of the ester in 28 days in a lab study.