Lutein and zeaxanthin are essential to eye health.
The two major carotenoids in the human eye are lutein and zeaxanthin. They are often referred to as xanthophylls or macular pigment. In nature, lutein absorbs excess light energy to prevent damage to plants from too much sunlight, but in humans, we use lutein in our eyes to prevent UV damage. Lutein is a carotenoid found widely in egg yolks, vegetables and some other plants. It's a yellow pigment, but in high concentrations, it appears orange-red. Zeaxanthin is an antioxidant carotenoid found in your macula, the small central part of your retina responsible for detailed central vision.
Both molecules look and behave the same, but zeaxanthin is more polar and is a scavenger of damaging single oxygen radicals than can cause cellular carnage.
The macula is the part of your eye that processes what you see directly in front of you. It's part of your retina and is key to your vision. The carotenoids are thought to function as antioxidants and as a blue light filter, to protect the eye from light damage and age-related macular degeneration (ARMD).
It's quite incredible, that among the 1000+ identified natural carotenoids, only lutein and zeaxanthin have the ability to pass the blood–retina barrier and accumulate in the human eye. The presence of lutein and zeaxanthin in the eye relies entirely on the human diet. You must either get them from a range of lutein and zeaxanthin-rich foods or use supplements. The best approach is to do both because the quantities in foods vary greatly. Lutein and zeaxanthin may not be absorbed well from certain foods and supplements.
There is a third carotenoid in the eye called meso-zeaxanthin. It is converted from lutein and is believed to be formed in the retina. It is rarely found in nature.
In recent years, several studies have reported that high levels of lutein and zeaxanthin lower the risk of certain eye disorders related to free radical generation. If people increase their intake of antioxidant vitamins and carotenoids, they could prevent cataracts and other eye problems.
Where can you get lutein and zeaxanthin from?
Egg yolk and maize contained the highest percentage of lutein and zeaxanthin compared with total carotenoids. Maize is the vegetable with the highest quantity of lutein, but with terrible absorption, and orange pepper is the vegetable with the highest amount of zeaxanthin (37% of total carotenoids). Substantial amounts of lutein and zeaxanthin are also present in kiwi fruit, grapes, spinach, orange juice, zucchini, and squash.
But the answer is a little more complex because lots of what you read about lutein and zeaxanthin is misleading. This is due to:
- Quantities of lutein and zeaxanthin are grouped together.
- Reported quantities in common foods vary wildly because it depends upon the source of the food. For instance, a battery hen will produce eggs that are low in carotenoids, and a free-range hen will lay eggs rich in carotenoids.
- The bioavailability of lutein and zeaxanthin varies enormously.
- It depends on what you eat the food with. For instance, the bioavailability of zeaxanthin in Goji berries doubles when eaten with a tiny amount of coconut oil.
The amount of a carotenoid that is absorbed through the intestines and is able to reach appropriate tissues is generally known as bioavailability. The high amount of carotenoids in certain foods is negated with low bioavailability. A classic example is β-carotene from carrots. Large amounts of zeaxanthin in corn is not highly bioaccessible, but the zeaxanthin in egg yolk is highly available. The same goes for the bioavailability of lutein and zeaxanthin when taken as a supplement.
While there’s no recommended daily intake for lutein, studies have found health benefits at a dose of 10 mg per day. Pasture-fed eggs range from 1 - 3mg of lutein. There is also no recommended daily intake for zeaxanthin, but studies have found health benefits at a dose of 2mg/day. Pasture-fed eggs contain 0.7-1.5mg of zeaxanthin, (the higher values taken from chickens fed specific feeds). Commercial factory eggs score very low. One study showed that eating only 1 store-bought egg per day can significantly increase both serum lutein and zeaxanthin concentrations without elevating cholesterol.
Let's take a look at an analysis of several foods. The first table shows the percentage of Lutein out of total carotenoids. It shows that numerous foods have a significant portion of lutein. Maize, egg yolks, kiwi, pumpkin, squashes and red grapes are clear winners. The overall occurrence of zeaxanthin in natural food products is low. The broad majority of xanthophyll-rich foods contain way more lutein than zeaxanthin.
The second table shows the foods sorted in order of percentage zeaxanthin content. You can see that there's only a dozen foods with a decent proportion of zeaxanthin compared to other carotenoids. We have to stress that these two tables show the percentages of lutein and zeaxanthin out of total carotenoids. It doesn't show absolute quantities.
Sources of zeaxanthin
The most predominant sources of zeaxanthin present in the human diet are corn-based foods along with peppers and egg yolks. The data is very sketchy but this 2020 article shows the foods that contain high amounts. The figures quoted are in micrograms per gram (so you would divide the number by 10 to get milligrams per 100g).
You might think that having a kale shake and a big bag of maize Doritos would give you the eyesight of superman, but the bioavailability is terrible. The best bet is to eat peppers, hot chilli peppers, eggs, potatoes, and kale. If you can get hold of some exotic options, like goji berries, sea buckthorn berries, and cape gooseberries, then you will supercharge your intake of zeaxanthin.
We shouldn't forget the humble potato. Especially well-cultivated varieties with yellow flesh. They must have yellow flesh. The different types of xanthophylls show variable concentrations in various potatoes. Some yellow flesh potato varieties can have up to 1.7mg of lutein per 100g, and 1.8mg of zeaxanthin per 100g. Here are some foods and their zeaxanthin levels per 100g.
Hot chili peppers 123mg.
Red Pepper 5.0 – 9.7mg.
Green Pepper 0.17 – 0.57mg.
Orange Pepper 6.2mg.
Yellow Pepper 0.44mg.
Kale 16.3 to 246mg.
Goji berry 123mg.
Red Chinese lantern fruit, (Cape Gooseberry) 84.7–103.5mg.
Sea buckthorn berries 19.3–42.4mg.
Kale and spinach are both very interesting because the bioavailability of the 2 macular carotenoids is 5 times that of beta-carotene. Eat your spinach and kale in the form of a smoothie or juice. This is the best way to obtain the antioxidant lutein, according to research from Linköping University, Sweden. The only downside to kale and spinach is the high levels of anti-nutrients, such as oxalates that bind to calcium and magnesium, and goitrogens which affect thyroid health.
Sources of Lutein.
The most predominant sources of Lutein present in the human diet are spinach, kale, peppers and egg yolks. It's very hard to find believable, unbiased data for lutein content. Some studies even listed cheetos and corn snacks! Here are some foods and their lutein levels per 100g.
Green beans, 0.3mg.
Orange pepper, 0.2-0.4mg.
Romaine Lettuce, 3.8 mg.
Pistachio nuts 1.4mg.
Whole Eggs 0.24mg.
Egg yolk 0.65mg.
Do Lutein and zeaxanthin supplements work?
In a scientific study, it was found that serum lutein content rose dramatically over a period of 12 weeks. This was based upon supplementing with 6mg, 10mg and 20mg of lutein, with some zeaxanthin. The baseline results for people who didn't supplement were pretty low, showing that modern diets either have low lutein content or, low lutein bioavailability. It was also found that levels of the stress hormone, cortisol, also reduced over the 12-week period. Results for serum zeaxanthin are hard to find.
In another study, long-term supplementation with 4mg and 20 mg of lutein, increased plasma lutein concentrations 3.5-fold and 10-fold respectively.
In a separate food supplementation study, egg yolk supplementation increased plasma lutein by 28% and zeaxanthin by 142%. Supplementation of corn oil increased plasma lutein by 50% and zeaxanthin by 114%.
The Central Retinal Enrichment Supplementation Trials (CREST).
These were European large trials. The CREST 1 trial used a ratio of 10 to 10 to 2 (Lutein, zeaxanthin and meso-zeaxanthin). The CREST 2 trials looked at carotenoids plus Vitamins A & C, plus zinc and copper.
The CREST 1 trial showed a massive boost to blood levels of Lutein, zeaxanthin and meso-zeaxanthin. These were 500 to 1000% increases.
The brain really wants lutein.
Lutein is pretty much the only carotenoid in the brain. In an NIH funded study, it was found that lutein was present in the brain and that it has a huge correlation with cognition and brain health. There was also a particular link with Omega 3, (DHA), working hand in hand with lutein in the brain. DHA is a long molecule with a lot of double bonds, and it can be easily oxidised. Lutein is thought to have a protective role with omega 3 in the brain. The double-blind placebo-controlled trial found that a 12mg lutein supplement, over a period of 4 months improved executive function.
Lutein in breast milk.
The lutein in breast milk is highly bioavailable and passes quickly into the babies brain and eyes. The bioavailability of lutein in baby formula is much lower. A lack of lutein in infants' food could influence early visual development.
Other health benefits of Lutein.
- Cancer cell modulation.
- Edema reduction.
Other health benefits of zeaxanthin.
- Gastric cancer prevention
- Obesity control, thanks to the activation of AMPK.
- Treatment of Alzheimer's disease
You must get the two critical xanthophylls from food. Or you can take a lutein and zeaxanthin supplement. The safest approach is to do both. Bioavailability is greatly increased when carotenoids are eaten with good fats, such as coconut oil and virgin olive oil.
- Eat plenty of free-range eggs or ones that come from hens fed on carotenoids.
- Eat yellow flesh potatoes.
- Eat lots of peppers. Especially hot chilli peppers, and orange peppers.
- Eat kale and spinach.
- Snack in pistachios. Pistachios contain 1.4 mg lutein and zeaxanthin, per 100 g, about thirteen times more than the next highest nut type, hazelnuts, which contain only 0.1mg.
- Eat parsley, in Mediterranean dishes such as tabooleh.
- Eat goji berry products with some coconut oil, just 1% of added coconut oil doubled the zeaxanthin bioavailability.
- Eat Quality protein maize, or QPM. This is a family of maize varieties that contains nearly twice as much lysine, tryptophan, amino acids and carotenoids.
- Try and source some of the more exotic fruits that at high in carotenoids.
- Take a 20mg supplement that contains Lutein, zeaxanthin and meso-zeaxanthin. Make sure it's taken with some healthy fats or oils.
Please take your eye health seriously and try an avoid excessive screen time and blue light exposure.