Lutein

Lutein is a yellow pigment in the carotenoid family, the same family as beta-carotene and astaxanthin. Its name comes from the Latin luteus, which means yellow. Only plants make it. In green leaves, two xanthophylls, most likely lutein, sit next to chlorophyll in the light-harvesting complex. They play a major part in handling its light energy.

Animals take lutein in with their food. More than 85% of the carotenoids in egg yolk are lutein and zeaxanthin. Three yellow songbirds, the yellow warbler, the common yellowthroat and the evening grosbeak, color their feathers with lutein alone.

In people, lutein and zeaxanthin are the only two dietary carotenoids that cross the blood-retina barrier. They build up in the macula, the small central part of the retina that gives sharp, detailed vision, and together they make it yellow. The eye even converts some lutein into a third pigment, meso-zeaxanthin, which is rarely found in food. Lutein is also the main carotenoid in human brain tissue.

Here is what most readers do not know. The biggest trial of lutein for the eye, AREDS2, found no clear extra protection against advanced macular degeneration in its main analysis. Lutein is in the current AREDS eye formula mainly as a replacement for beta-carotene, which was linked to more lung cancers.

Health benefits of lutein

• ★★Raised macular pigment densityIn 20 trials, lutein and zeaxanthin supplements raised macular pigment density, a measure of eye pigment, in people with and without age-related macular degeneration (AMD). The rise was 0.07 in AMD and 0.09 in healthy people, and eating eggs raised it by 0.037 across 5 trials.
• ★★No clear slowing of advanced macular degenerationIn AREDS2 (4,203 people at risk), 31% on placebo and 29% on lutein plus zeaxanthin progressed to advanced AMD, a gap that could be chance. Exploratory analyses found 0.82 times the risk of late AMD against beta-carotene.
• ★★Slightly sharper vision and better contrast in AMDIn 8 trials of 1,176 people with AMD, supplements slightly sharpened vision (acuity score fell by 0.04, lower is sharper). Contrast sensitivity was better at all four detail levels tested.
• ★★Did not lower heart events or cataract surgeryIn AREDS2, 10 mg lutein plus 2 mg zeaxanthin a day did not clearly lower heart attacks, strokes or cardiovascular deaths (0.94 times the risk). It did not lower cataract surgery overall (0.96 times).
• ★★Mixed results for thinking skillsIn AREDS2, lutein plus zeaxanthin did not slow decline in thinking skills in 3,501 older adults with AMD. In a trial of 90 adults with thinking complaints, only visual memory and learning improved.

Foods high in lutein

The USDA data on this page measure lutein and zeaxanthin together. So every number in the ranking below is for the pair, not for lutein alone. Dark leafy greens and herbs lead. Garden cress (12,500 µg per 100 g) and spinach (12,198 µg) come first, followed by kale (6,261 µg), basil (5,650 µg) and parsley (5,561 µg).

Serving size changes the picture. A cup of spinach (30 g) holds 3,659 µg and a cup of kale (21 g) holds 1,315 µg. For comparison, the AREDS2 supplement held 10 mg of lutein plus 2 mg of zeaxanthin, or 12,000 µg in all. By the USDA figures, that is about 98 g of spinach or 190 g of kale.

Egg yolk does not make the top ten per 100 g, but it is well absorbed (see below).

How lutein works

Most of what we know about how lutein works comes from test tubes, cells, animals and donated eye tissue. Researchers keep coming back to four ideas. It filters blue light in the macula, it guards the fats in cell membranes, and it switches on the cell’s own defenses. It also collects in the macula and the brain with the help of binding proteins.

Here is each one, and what has been seen in people.

It filters blue light

The macular pigment sits in front of the photoreceptors, the light-sensing cells, so light passes through it first. Wald established in 1945 that the pigment absorbs light between 430 and 490 nm, with a peak near 460 nm. Lutein itself peaks at 445 nm and zeaxanthin at 450 nm.

By absorbing blue light, the pigment is thought to protect the photoreceptors below it from light damage. That damage may start with reactive oxygen made in a light-driven reaction. The same review says filtering blue light is also thought to cut glare and blur from chromatic aberration. Whether that protection prevents disease has not been shown.

It guards cell membranes

Lutein is a long molecule with a polar (water-loving) hydroxyl group at each end. In lipid vesicles used as model membranes, lutein and zeaxanthin lay across the bilayer at an average tilt of about 40 degrees from upright. Imaging and computer simulation both found this. A review says polar carotenoids in general span the bilayer with their polar ends anchored in the two surface zones.

The picture is not settled. An older study using linear dichroism found zeaxanthin mostly upright, but lutein in two pools, one upright and one lying parallel to the membrane.

In artificial membranes, lutein and zeaxanthin protected against free radical attack with almost the same strength. Zeaxanthin did better during long UV exposure, because lutein itself was slowly destroyed by the light.

In a separate test, both carotenoids stopped light from oxidizing A2-PE, a by-product of vision that builds up in retinal pigment cells. Both did better than vitamin E. Zeaxanthin was more effective than lutein, and neither was used up much.

It switches on the cell’s own defenses

Nrf2 is a control protein that tells cells to make more of their own protective enzymes. In human retinal pigment cells grown in a dish, lutein moved Nrf2 into the nucleus. After 4 hours this was 1.5 times more than with lutein-free micelles.

After 24 hours the NQO1, GCLM and HO-1 genes were up 1.7-, 1.4- and 1.8-fold. NQO1 enzyme activity rose 1.2-fold. The authors conclude that lutein is not only a direct antioxidant.

It collects in the macula and the brain

Lutein does not spread evenly. A review reports that carotenoid levels near the fovea, the center of the macula, are nearly 100 times those at the retina’s edge. The mix changes too. In donor eyes, lutein made up about 1 part in 3.4 of the pair at the center and more than two thirds at the edge.

Binding proteins help. StARD3 binds lutein, and a second protein, GSTP1, binds zeaxanthin (Li, 2011; Bernstein, 2016).

Lutein reaches the brain too. Xanthophylls make up about 70% of all carotenoids in every brain region. In monkeys, lutein in the macula tracked lutein in several brain regions. In human donors, pigment in the retina was related to lutein plus zeaxanthin in the occipital cortex.

In brain tissue, lutein and StARD3 levels were closely related in infants (r = 0.75). The link was weak in people aged 55 to 86 and absent in centenarians. The samples were small, so treat these as hints.

What has been seen in people

These effects are much easier to show in a dish than in a person. Supplements do raise macular pigment, by 0.07 in people with macular degeneration and 0.09 in healthy people in a meta-analysis of 20 trials. Acuity and contrast sensitivity gains in people with macular degeneration were small, and 115 healthy young adults recovered faster from a bright flash.

But the 4,203-person AREDS2 trial did not find clear protection against advanced macular degeneration. So a higher pigment level has not been shown to prevent disease. For the brain, small trials reported better attention and visual memory, while AREDS2 found no effect on the rate of decline in thinking skills. All of these are among the study cards above.

Is lutein safe? Supplements, dose and interactions

Lutein from food is not a safety concern. EFSA, the European food safety agency, set an acceptable daily intake for lutein from marigold (Tagetes erecta), the food color E 161b. That acceptable daily intake (ADI) is 1 mg per kg of body weight, about 70 mg for a 70 kg adult by our arithmetic. EFSA also noted that high-end estimates of intake from the color were above that ADI.

In the US, the FDA had no questions about crystalline lutein added to foods at 0.3 to 3 mg per serving. For meal replacements the level was 6 mg. That was GRAS notice 140 (Kemin Foods, 2004).

• Trial doses and side effects. Most trials used 10 to 12 mg of lutein plus 2 mg of zeaxanthin a day, and a few used 20 mg of lutein. In AREDS2, 4,203 people took 10 mg plus 2 mg for about 5 years, and adverse events did not differ from placebo. A 6-month trial in 90 adults also reported no clear side effects.
• Very high doses. One case report describes a woman in her sixties who took 20 mg of lutein a day for 8 years and ate lutein-rich greens daily. She had yellow crystals in the fovea without vision loss. The crystals were resolving in one eye 7 months after she stopped the supplement. One case cannot prove cause, but she took twice the usual 10 mg.
• Smokers and beta-carotene. Lutein replaced beta-carotene in the AREDS formula because beta-carotene was linked to more lung cancers, mostly in former smokers. At 10 years, the odds of lung cancer were 1.82 times higher on beta-carotene, and not clearly higher on lutein and zeaxanthin (1.15).
• Pregnancy, babies and other pills. One trial gave 10 mg lutein plus 2 mg zeaxanthin to 47 pregnant women. But its report covers carotenoid levels and eye measures, not safety, so ask your doctor. A 1999 review says carotenoids can compete with each other for absorption, but its findings conflict. We found no controlled study of lutein with a prescription drug.

How to get more lutein

• Best food. Garden cress, spinach and kale lead the ranking above by weight. In leafy greens nearly all of the pair is lutein, with only 0 to 3% of carotenoids as zeaxanthin. Egg yolk helps too. One egg a day for 5 weeks raised blood lutein by 26% in 33 older adults. But in 11 people eating 1.3 yolks a day, LDL cholesterol rose 8 to 11%.
• Eat it with fat. In 7 people, a salad with fat-free dressing gave essentially no carotenoid absorption. In 12 women, absorption of all carotenoids was highest with 32 g of soybean oil in the dressing. Lutein rose only slightly across 0 to 4 g.
• Chop or blend. In a lab digestion model, pureeing spinach freed 3 to 4 times more lutein than whole leaves, but stir-frying minced spinach erased the gain. In 10 men, lutein-enriched eggs raised blood lutein more than the same 6 mg from a supplement or spinach.

History of lutein

The name lutein comes from the Latin luteus, yellow. In 1945 Wald showed that the yellow pigment of the human macula absorbs light between 430 and 490 nm. In 1985 Bone, Landrum and Tarsis matched the pigment by chromatography to lutein and zeaxanthin. In 1988 Bone and colleagues mapped how the ratio of the two changes across the retina.

Population links to diet came next. In a 1994 US case-control study, the top fifth of carotenoid intake had a 43% lower risk of advanced macular degeneration. The strongest link was for lutein and zeaxanthin. Findings like this led to AREDS2. It enrolled 4,203 people at 82 US centers between 2006 and 2012 to test adding lutein and zeaxanthin to the AREDS formula.

AREDS2 reported in 2013 that the addition did not clearly lower progression in its main analysis. Because beta-carotene brought more lung cancers, the revised AREDS supplement replaced it with lutein and zeaxanthin. For the food color E 161b, EFSA’s 2010 review was based on lutein from marigold, Tagetes erecta.

Frequently asked questions about lutein

What does lutein do for the body?

Lutein works mainly in the eye. It collects in the macula, where it filters blue light, and in lab tests it also acts as an antioxidant. Supplements raised macular pigment density by 0.07 in people with macular degeneration and 0.09 in healthy people, in a meta-analysis of 20 trials. They also slightly improved acuity and contrast sensitivity in macular degeneration. Beyond the pigment increase, no finding here reaches strong evidence.

Which foods are high in lutein?

Dark leafy greens and herbs. USDA data, which count lutein and zeaxanthin together, put garden cress (12,500 µg per 100 g) and spinach (12,198 µg) first. Kale (6,261 µg), basil and parsley come next. A cup of spinach has 3,659 µg and a cup of kale 1,315 µg. Egg yolk is another well-absorbed source.

How much lutein should you take a day?

We found no official recommended amount. Most trials used 10 mg of lutein with 2 mg of zeaxanthin, the AREDS2 dose, and some used up to 20 mg of lutein. EFSA’s acceptable daily intake is 1 mg per kg of body weight, about 70 mg for a 70 kg adult. Ask an eye doctor before taking it for macular degeneration.

Does lutein have side effects?

Trials reported few. In AREDS2, with 4,203 people over about 5 years, adverse events did not differ from placebo. One case report links 20 mg a day for 8 years, plus a lutein-rich diet, to yellow crystals in a woman’s fovea. They began to clear after she stopped. Tell your doctor about any supplement in pregnancy, because we found no safety trials there.

Does lutein help prevent macular degeneration?

Not proven. In AREDS2, 10 mg of lutein plus 2 mg of zeaxanthin did not clearly lower progression to advanced disease (31% on placebo against 29%). A Cochrane review found little or no difference with them on their own (0.94 times the risk). Lutein and zeaxanthin do look like a better choice than beta-carotene in the AREDS formula (0.82 times the risk). In cohort studies, the highest intake went with 26% less late disease.

What is the difference between lutein and zeaxanthin?

They are close relatives that sit side by side in the macula. Lutein absorbs light at 445 nm and zeaxanthin at 450 nm. Leafy greens supply mostly lutein. The center of the macula holds more zeaxanthin (lutein is about 29% of the pair there) and the edge more lutein. Most trials gave them together, so their effects cannot be told apart.

Is lutein the same as luteolin?

No. Lutein is a yellow carotenoid found in leafy greens and egg yolk. Luteolin is a flavonoid, a different class of plant compound, found in foods such as carrots, peppers, celery, olive oil, peppermint, thyme, rosemary and oregano. Most research on luteolin is preclinical. Check the spelling on a label.

When is the best time to take lutein?

No trial here tested time of day. Lutein dissolves in fat, so take it with a meal that contains some. In 7 people, a salad with fat-free dressing gave essentially no carotenoid absorption. In 12 women, absorption was highest with 32 g of oil. Several trials above ran 6 to 12 months.