Chances are, you’re not as familiar with lutein as you are, say, beta carotene.
That’s because lutein, and it’s ‘sibling’ zeaxanthin (zea zan THin), haven’t had similar PR.
Everyone seems to know that beta-carotene is ‘good for my eyes’ because we’ve been told that some of the beta-carotene we eat, gets converted into vitamin A.
However, if there’s a topic that needs promoting, it’s lutein & zeaxanthin AND the amazing things these pseudo-nutrients can do for your health.
This post discusses the many benefits of lutein, and of course, it’s a similarly structured sibling, zeaxanthin, and how best to get more of them into your diet including both food and supplements.
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What is lutein?
Lutein is one of several carotenoids found in the human diet just like lycopene or alpha and beta carotene etc are.
Carotenoids are compounds of various hues of yellow, orange, and red pigments produced by plants.
FUN FACT: there are more than 750 naturally occurring pigments made by various plants, algae and photosynthetic bacteria. Fruits & vegetables produce most of the 40 to 50 carotenoids found in the human diet.
Of the dozens of carotenoids in the human diet, only a handful or so make their way into our bodies; most are not absorbed (1, 2).
Thankfully, lutein and zeaxanthin are two that are efficiently absorbed and taken up by various tissues and organs.
Lutein and zeaxanthin
Lutein and zeaxanthin are two important carotenoids. They’re produced by various plants that give certain fruits and vegetables a yellow to reddish hue.
They’re structurally very similar, with just a slight difference in the arrangement of their atoms (3).
PRO TIP: lutein is often used interchangeably with zeaxanthin in that the two carotenoids often occur together in foods and because lutein is converted by your body into zeaxanthin.
Both are potent antioxidants and offer a range of health benefits to your brain, skin, liver and more.
However, lutein and zeaxanthin are best known for protecting your eyes. Most of the research on these two carotenoids have focused on eye health and vision.
Vitamin A activity
Everyone has heard of vitamin A and most have heard comments like “carrots and pumpkin are good sources of vitamin A”. Sadly, this isn’t accurate.
Vitamin A (retinol, retinal etc) is a different molecule than the carotenoids. Vitamin A is found exclusively in animal foods such as liver, fish, milk, cheese, and eggs.
Because some of the carotenes we eat (alpha & beta carotene and beta-cryptoxanthin) are converted into vitamin A, they are said to have “provitamin A activity” but those plant foods DO NOT contain vitamin A themselves.
Am I splitting hairs? Maybe. But it’s important because not everyone converts provitamin A carotenoids into retinol efficiently.
In fact, about 1/3 of the population has a genetic mutation that makes them poor converters. This is one of the reasons many people don’t do well on a vegan diet.
Because carotenoids are not absorbed as easily as preformed vitamin A (retinol/retinal) is, vitamin A is now measured as RAEs or “retinol activity equivalents“. This ultimately is a measure of how well a carotenoid is converted into vitamin A (4).
Obviously, pre-formed vitamin A has an RAE of 1 since it’s already in the preferred form.
It takes a relatively large amount of a given carotenoid to be converted into an equal amount of vitamin A. Depending on the carotenoid, it takes 12-24 times more to produce an equal amount of vitamin A.
On that note, lutein and zeaxanthin don’t have any vitamin A activity.
Because vitamin A is already, well, vitamin A, getting enough it is easy and it takes a lot less vitamin A-rich animal foods to meet your daily requirement (4).
Lutein, zeaxanthin and meso-zeaxanthin
I know, it’s a lot, but bear with me. Foods contain both lutein and zeaxanthin but there are little to no foods that contain meso-zeaxanthin.
While it’s hard to see at first glance, the structures below are different, if ever so slightly.
Your body will convert lutein into zeaxanthin and meso-zeaxanthin. Where this is very important is in the back of your eyes, in part of your retina called the macula.
Meso-zeaxanthin is the new kid on the block. It hasn’t gotten the same attention as the others have even though researchers have known about it for over 20 years. It’s actually meso-zeaxanthin that’s located in the very center of your macula where it plays a crucial role in protecting it.
When it comes to eye health, all three are important and the role of supplements will be talked about as it relates specifically to eye health and optimal vision.
Zeaxanthin and lutein benefits your whole body. Both go way beyond eye health; they provide benefits that make them some of the best anti-aging and longevity friends you definitely want.
It’s estimated that lutein and zeaxanthin only make up about 16% of the total carotenoids in the human diet yet they make up between 66-77% of the total carotenoids in the brain, assuming of course you consume enough of them (5, 6, 7).
Higher brain concentrations of lutein and zeaxanthin are associated with, and predictive of, better cognitive function with aging (8, 9).
In a small 4-month study in older women (ages, 60 to 80 years) without cognitive impairment, supplementation with lutein (12 mg/day) and zeaxanthin (0.5 mg/day) significantly improved cognitive test performance (10)
Research on college students is found that the amount of lutein in the brain had an impact on mental sharpness and memory. Lutein supplementation improved mental processing speed and efficiency in both younger and older adults (11).
Like most things in nutrition, earlier is better. Getting more lutein & zeaxanthin in early to middle adulthood before older age may provide the best benefit.
In addition to lutein’s antioxidant and anti-inflammatory properties, it seems to preserve ‘neuro-electrical’ activity and those with higher intakes of lutein had neuro-electrical signatures similar to those much younger. In other words, older brain’s rich in lutein behave more like younger brains (12). Sweet.
Lutein has also been linked to intelligence in older adults. (14). Eating more lutein-rich foods might just help us keep our smarts about us as we grow older.
Higher intakes of lutein and zeaxanthin are also associated with a reduced risk of stroke and lutein/zeaxanthin ingestion post-stroke improves recovery, enhances survival and reduces brain cell (neuron) damage (15, 16).
In Western countries, age-related macular degeneration (AMD) is one of the leading causes of preventable blindness in those over 60 (17).
Lutein for eyes has been promoted because it, along with zeaxanthin and meso-zeaxanthin, helps to protect the macula from the damaging effects of blue light.
The macula is the center part of your eye’s retina. Your eye’s lenses focus incoming light onto the macula which is responsible for clear, central vision.
Your eyes selectively concentrate both lutein and zeaxanthin in the macula where some of it is converted to meso-zeaxanthin. The amount of these carotenoids in the macula is referred to as the “macular pigment density”.
More carotenoids = greater pigment density = greater absorption of blue light, and, you guessed it = less risk for vision loss (19, 20).
Think of these pigments as a natural internal sunblock or sunglasses for the inside of your eye 🙂
By doing so, they reduce the risk for AMD by preventing a substantial amount of the blue light entering the eye from reaching the underlying structures involved in vision thereby protecting against light-induced damage (18).
FUN FACT: depending on the amount of lutein, zeaxanthin & meso-zeaxanthin in the macula, up to 90% of the blue light can be absorbed by these carotenoids, protecting critical visual structures from damage. Whoa !
These superstar pigments can also reduce your risk for cataracts. Of all the carotenoids in the diet, only lutein and zeaxanthin are found in your eye’s lens (21).
Long story short, a higher dietary intake and higher blood concentrations of lutein and zeaxanthin have been associated with a reduced risk for cataracts (22, 23, 24, 25, 26, 27, 28).
While the research to support lutein and zeaxanthin for eye health is robust, not all studies showed benefit (29, 30).
Skin is the largest organ and it provides a first-line defense against external threats. Your skin is exposed to lots of damaging ultraviolet (UV) rays every single day.
Because lutein and zeaxanthin are fat-soluble, they accumulate within fatty tissues including the fat that makes up the membranes of your skin cells thereby providing antioxidant protection (31).
As a bonus, lutein and zeaxanthin may protect your skin cells from premature aging and UVB-induced skin cancer (32).
A small study in 46 people with mild-to-moderate dry skin had significantly improved skin tone with 10 mg of lutein and 2 mg of zeaxanthin compared to those in the control group who didn’t (33).
Lutein and zeaxanthin may help to reduce atherosclerosis, and therefore heart disease (34).
They seem to exert many different effects that benefit the health of your blood vessels while reducing one of the first steps in the atherosclerotic process: the oxidation (damaging) of LDL cholesterol (35).
Positive effects of lutein include reducing blood pressure, reducing arterial thickness (which reduces blood pressure and blood vessel damage), reducing inflammation (36, 37).
Like many phytonutrients, lutein and zeaxanthin have potent anti-inflammatory properties. In a study published in Atherosclerosis, researchers demonstrated lutein’s ability to suppress long-term inflammation in patients with coronary heart disease (28).
Lower inflammation is predictive of better outcomes in those with chronic diseases such as cardiovascular disease, diabetes, high blood pressure, insulin resistance, and autoimmune diseases.
Both lutein and zeaxanthin have been shown to minimize damage caused by oxidation and inflammation in those with retinal ischemia and diabetic retinopathy too (29).
Regarding their anti-inflammatory properties, they do so by specifically inhibiting two pro-inflammatory processes: they temper genes that produce an enzyme nitric oxide synthetase (nNOS) and the expression of an inflammatory pathway called COX-2 (29).
Anti-inflammatory drugs such as Naproxen, Ibuprofen, Celebrex etc work in a similar fashion, they’re known as COX-2 inhibitors.
Cancer risk reduction
Diets rich in plant foods are well understood to improve overall health including lowering the risk for cancers.
What’s unique about lutein is that it appears to selectively inhibit the growth of breast cancer cells through several mechanisms (29).
Lutein also appears to appropriately induce something called apoptosis, a.k.a. programmed cell death.
Normally, all cells have a limited number of times they can divide and reproduce in order to prevent out-of-control growth. They do this by committing “cell suicide”.
Cancer cells have somehow hijacked this mechanism and turned it off, allowing them to grow out-of-control; lutein seems to fix that (30, 31).
How much lutein should you get?
What is the ideal lutein dosage? While the exact amount is unknown, we have a pretty good idea.
It’s estimated that the average intake of lutein (and zeaxanthin) is about 2 mg per day in North America. Studies, however, show that benefits take off when you get between 6-10 mg per day on average.
This is an important point. No one is expected to consume 6-10 mg per day although that’s easily achieved if lutein and zeaxanthin-rich foods are consumed daily.
But, by eating several servings of lutein-rich foods weekly, you can reach the average daily intake target that search has found to be beneficial.
Case in point, the amount of lutein in 250 ml / 1 cup of the following has:
- Spinach, frozen, cooked: 25 mg
- Kale, frozen, cooked: 24 mg
- Summer squash, cooked: 4 mg
- Green peas, frozen, cooked: 3.8 mg
Eating several servings of different lutein-rich foods throughout the week will easily top up the estimated 2 mg most people are already getting.
Wondering what lutein foods to include more often? Foods rich in lutein and zeaxanthin include:
- Egg yolks, lutein-enhanced eggs
- Green peas
- Orange pepper
- Kiwi fruit
- Pumpkin & winter squash
- Dandelion, turnip, mustard & beet greens
- Romaine lettuce, radicchio
- Swiss chard & collard greens
Because lutein and zeaxanthin are fat-soluble, like all carotenoids are, they’re absorbed best when eaten with fat.
Some foods like avocado naturally contain fat, but others, like spinach, kale, corn etc don’t.
Eating lutein and zeaxanthin-rich foods as part of a meal where fat is added (like butter or olive oil) or with foods that contain fat (like meats, fish, cheese) will enhance the total amount of lutein/zeaxanthin absorbed.
What about a lutein supplement? This is a great and easy option to help top up the tank. As with dietary sources, supplemental lutein and zeaxanthin are best absorbed when taken with a food or beverage that contains fat.
You can buy standalone supplements that contain just lutein or others with lutein and zeaxanthin. Some multivitamins will have them as well but typically in much smaller amounts.
Supplement companies get their lutein and zeaxanthin from marigolds; there’s a reason those flowers are bright yellow and yellow/orange.
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As with any supplement, zeaxanthin and lutein side effects need to be considered. Good news, adverse effects of lutein and zeaxanthin have not been reported (32).
One large study did find some yellowing of the skin in those taking lutein and zeaxanthin supplements (33), not unlike when people eat a lot of alpha and beta-carotene containing foods (most common in heavy carrot juice drinkers). The colouring is not considered harmful.
They have an excellent safety record (34, 35).
Lutein and zeaxanthin are two potent carotenoids.
Although they can’t be converted into vitamin A, another important nutrient, they’re no shrinking violets. They are rock stars in their own right.
A lot of different foods have lutein and zeaxanthin but they’re found in high amounts in dark-green and dark-green leafy vegetables. As an alternative, you can find them as supplements too.
These carotenoids have a variety of health benefits but are best known for their role in eye health and vision. Gaining traction though is ongoing research that’s demonstrated a role for lutein and zeaxanthin in preserving cognitive function as we age.
In addition to tempering inflammation, when consumed in optimal amounts, lutein and zeaxanthin protects your skin from UV radiation and may lower your risk for cancer.
Aim to get a daily average of 6, or better, 10 mg of lutein and 2 mg of zeaxanthin per day. You can do this by eating several servings of lutein-rich foods per week.
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Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, mental health. Follow me on Facebook, Instagram and Twitter.