Day: March 29, 2023

• Of all the known carotenoids, only lutein and zeaxanthin cross the blood-retina barrier to form macular pigment

• Lutein is also found in the brain, hinting at its importance for cognitive function

• Lutein, found in green leafy vegetables, egg yolks and more, helps form the retinal macular pigment, which is responsible for optimizing your visual performance and serves as a biomarker for the risk of macular diseases

• Lutein is protective against age-related macular degeneration, cataracts, glaucoma and other eye diseases

• Among young and older adults, lutein and zeaxanthin supplementation improves cognitive function

While there are about 850 known carotenoids, most are not found in the human body

and only lutein, zeaxanthin and astaxanthin cross the blood-retina barrier to form macular pigment.

Your retina is an extension of your brain,

where lutein also accumulates throughout the human lifespan, hinting at its importance for both vision and cognitive function.

In fact, if you have dementia, you’re likely deficient in lutein, which crosses the blood-brain barrier and has a protective, anti-inflammatory effect.

While lutein is available in supplement form, it’s also found in a wide variety of foods, including dark leafy greens, avocados and egg yolks.

Lutein concentrates in your macula,

which is the part of your retina responsible for central vision. Along with zeaxanthin and mesa-zeaxanthin (a metabolite of lutein), these three carotenoids form the retinal macular pigment, which not only is responsible for optimizing your visual performance but also serves as a biomarker for the risk of macular diseases.

Lutein is also found in the lens, where it helps protect against cataracts and other age-related eye diseases.

Among carotenoids, lutein is the most efficient at filtering out blue light — the type that comes from cellphones, computers, tablets and LED lights.

Blue light induces oxidative stress in your eyes, which increases the risk of cataracts and macular diseases. Lutein, however, acts as a shield against it. According to a team of researchers from Harvard Medical School and The University of Hong Kong, writing in the journal Nutrients:

“As the peak wavelength of lutein’s absorption is around 460 nm which lies within the range of blue light, lutein can effectively reduce light-induced damage by absorbing 40% to 90% of incident blue light depending on its concentration.

The outer plexiform layer of the fovea, where the majority of axons of rod and cone photoreceptor cells are located, is the retinal layer having the highest density of macular carotenoids including lutein. Hence the photoreceptors are protected against photo-oxidative damages from blue light.”

Lutein also suppresses inflammation and the expression of vascular endothelial growth factor (VEGF),

which stimulates the formation of blood vessels and is upregulated in many tumors.

“As inflammation and abnormal angiogenesis in retinal vasculature are major pathogenic mechanisms of many ocular diseases, lutein’s functions in suppressing inflammatory response and VEGF expression make it effective in reducing the severity of these diseases,” the team noted.

Further, lutein may improve visual acuity while helping to reduce cell loss after injury.

It is important to understand that VEGF can be very helpful or detrimental depending on the circumstances. When building muscle, VEGF expression is vital to nourishing Type 2 muscle fiber stem cells. However, if there is a disease process going on, then excessive VEGF levels can be pathologic. In healthy people, though, VEGF expression is generally considered healthy.

In my view the most important strategy to prevent age-related macular degeneration (AMD) is through the radically lowering of the omega-6 fat linoleic acid. AMD was virtually unknown prior to the refining of seed oils in the late 1800s. Now it is a leading cause of blindness.

Lutein also may help prevent AMD,

which is the leading cause of vision loss and blindness for Americans aged 65 and older.

By 2050, it’s estimated that 288 million people worldwide will be affected, up from 196 million in 2020.

Not only are higher blood levels of lutein and other carotenoids associated with a lower risk of AMD, but one study found people with the highest lutein and zeaxanthin intake had a 65% lower incidence of neovascular AMD compared to those who consumed the least.

Lutein also shows promise for diabetic retinopathy, which affects one-third of diabetes patients.

Along with improving retinal thickness and function, lutein may lower the risk of development or progression of diabetic retinopathy.

Cataracts, which are estimated to affect over 90% of adults aged 70 and over, are also less common in people with higher lutein intakes.

In one study, those who consumed the most lutein had a 50% lower likelihood of cataracts than those who consumed the least.

Glaucoma, another leading cause of blindness worldwide, is also linked to lutein consumption. A systematic review revealed that lutein enhanced neuroprotection of retinal ganglion cells, helping to preserve synaptic activity.

Further, not only was greater consumption of carotenoids in the diet associated with a lower glaucoma risk, but higher carotenoid levels in macular pigment helped improve visual performance in eyes affected by the disease.

Even myopia, or nearsightedness, which causes faraway objects to appear blurry while close-up objects look clear, may have a lutein connection.

In a study looking into the effects of vitamin D and ultraviolet B exposure on myopia, it was found, unexpectedly, that subjects with the highest lutein concentrations had 40% reduced odds of myopia.

While lutein is well-known for its role in eye health, its role in brain health is being increasingly explored. The connection makes sense, since as your vision worsens with age, so too may your cognitive abilities.

Research shows visual impairment at a distance is associated with declining cognitive function over time, while “maintaining good vision may be an important interventional strategy for mitigating age-related cognitive declines.”

Meanwhile, studies support the beneficial effects of lutein on brain health. In a trial of young, healthy adults, supplementation with lutein and zeaxanthin improved levels of these carotenoids in the central nervous system along with boosting cognitive function.

Among older adults with a mean age of 73.7 years, lutein and zeaxanthin supplementation also improved cognitive function, including boosts in complex attention and cognitive flexibility domains, compared to those taking a placebo.

Men taking part in the study also had improvements in composite memory. These benefits were seen with a daily lutein and zeaxanthin dose equivalent to that found in one-half cup of cooked kale or 1 cup of cooked spinach.

A literature search involving eight clinical trials further revealed that lutein and zeaxanthin in the blood or macula are associated with cognitive performance, and “there is an inverse relationship between a higher amount of macular pigment in the blood and lower risk of mild cognitive impairments or Alzheimer’s disease.”

In another example, among 60 adults between the ages of 25 and 45, those with higher levels of lutein in middle-age had more youthful neural responses than those with lower levels.

The researchers suggested eating more lutein-rich foods could therefore benefit your brain in middle age:

“While some age-related cognitive decline is to be expected in healthy aging, our data suggest that these effects may be less pronounced among adults with greater retinal carotenoid status, a marker of dietary patterns characterized by greater intake of green and leafy vegetables. Furthermore, these practices may provide neuro-cognitive benefit before the onset of older age, in early to middle adulthood.”

Lutein’s ability to protect against oxidative stress may also boost cardiometabolic health, according to a systematic review and meta-analysis. Both higher dietary intake and higher blood concentrations of the carotenoid were associated with better cardiometabolic health, including a lower risk of metabolic syndrome, coronary heart disease and stroke.

Lutein may support optimal cardiometabolic health by inducing beneficial vascular changes and offering antioxidant and immunomodulatory effects. Lutein’s anti-inflammatory effects also appear to by systemic, not restricted to the eyes, including an association with lower c-reactive protein (CRP),

a measure of heart disease risk.

Your body cannot make lutein, so you must get it from your diet. Following are 10 foods that are particularly rich sources of lutein.

• Dark leafy greens

• Carrots

• Broccoli

• Egg yolks

• Red and yellow peppers

• Sweet corn

• Avocados

• Raspberries

• Cherries

• Paprika

Lutein and other carotenoids are fat-soluble, so to optimize absorption be sure to consume it along with a source of healthy fat, such as coconut oil or grass-fed butter. Because organic, pastured egg yolks contain fat, they’re among the healthiest sources of lutein. You can often tell the eggs are free-range by the color of the egg yolk. Foraged hens produce eggs with bright orange yolks, indicative of higher amounts of lutein and zeaxanthin.

Further, consuming eggs along with vegetables that contain lutein may increase its absorption. In fact, eating whole eggs along with a raw mixed-vegetable salad increased absorption of lutein and zeaxanthin by four- to five-fold.

While there’s no recommended daily intake for lutein, one study found, “Dietary concentrations between 6 and 20 mg per day of lutein have been associated with a reduced risk of ocular disorders such as cataracts and age-related macular degeneration.”

Another paper, published in 2019 in PLOS ONE, found benefits to vision in those who took 10 mg or 20 mg of lutein per day, explaining:

“Our stratified analyses suggest the importance of providing lutein at sufficiently high doses and durations: daily doses of at least 20mg showed efficacy within 6 months, compared to 1 year for daily doses of 10mg. However, at least one study showed that 10 mg lutein had the same effect as 20 mg per day, which contradicts our results.

This raises the possibility that the efficacy of lutein supplementation depends on multiple factors. In any event, lutein or zeaxanthin appears to be safe in rats at up to 400mg/kg per day, and lutein appears to be safe in humans at up to 20mg per day.”

While the optimal dose of lutein in supplement form is still being determined, increasing your intake of lutein-rich foods is a simple and effective way to boost your levels of this important nutrient.

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Disclaimer: The entire contents of this website are based upon the opinions of Dr. Mercola, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked.

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. The subscription fee being requested is for access to the articles and information posted on this site, and is not being paid for any individual medical advice.

If you are pregnant, nursing, taking medication, or have a medical condition, consult your health care professional before using products based on this content.

• Patients with glaucoma who took melatonin supplements had decreased intraocular pressure

• Melatonin also helps to restore disrupted circadian rhythms in people with glaucoma

• Melatonin counteracts oxidative damage in the lens and may be a “potential therapeutic agent for cataract prevention/management”

• Melatonin may also be useful for neurovascular age-related macular degeneration (AMD) and dry AMD

• Melatonin also has antiviral, antiaging, anticancer, immunomodulatory and anti-inflammatory effects

Melatonin, well-known for its role in regulating your body’s circadian rhythm, is useful for far more than a good night’s sleep. This hormone was recently heralded for its role in eye health, and it may be an important compound for warding off age-related declines in vision.

Glaucoma, for instance, is among the leading causes of blindness, affecting 70 million people throughout the world. While its underlying causes are unknown, mechanical stress caused by elevated intraocular pressure (IOP) is known to damage retinal ganglion cells.

It’s been suggested that glaucoma is, in fact, a neurodegenerative disease, and damage to retinal ganglion cells affects not only vision but also circadian rhythms and sleep. People with glaucoma may have disrupted circadian rhythms compared to their peers,

and neuroprotective strategies that prevent damage to retinal ganglion cells could help with both this and glaucoma. In this regard, melatonin checks all the boxes.

In a study published in the Journal of Pineal Research, a team of scientists investigated the effects of melatonin supplements on patients with glaucoma.

Subjects took melatonin daily at 10:30 p.m. for 90 days, experiencing a number of benefits, including:

• Increased stability of systemic circadian rhythm via improved phase alignment and alignment with intraocular pressure

• Decreased intraocular pressure

• Improved function of retinal ganglion cells in those with advanced glaucoma

• Improvements to sleep and mood, particularly in those with advanced glaucoma

Previous research by the team found that melatonin was beneficial for disrupted systemic circadian rhythms and the cardiovascular system.

They explained:

“Being a principal chemical factor for sensing environmental light signaling and synchronizing peripheral clocks, melatonin serves both input and output of the circadian system. Melatonin is regarded as a promising substance to ameliorate complex glaucoma-associated conditions of compromised well-being (i.e., disrupted circadian rhythms, altered sleep and mood).

… Combined, these results provide evidence for melatonin efficiency in restoring disrupted circadian rhythms in glaucoma, with different effects of melatonin on systemic vs. local rhythms, suggesting that a personalized strategy for melatonin administration may further refine its benefits.”

Melatonin is often described as a pineal hormone,

but only 5% of your body’s melatonin — which is also a potent anticancer agent — is produced in your pineal gland. The other 95% is produced inside your mitochondria — provided you get proper sun exposure, which is intricately involved in melatonin production.

Meanwhile, melatonin receptors exist in several areas of the eyes, including the retina, lens and cornea, “which suggests that cells in these tissues may be targets for melatonin action,” researchers wrote in Pharmacology & Therapeutics.

This hints at melatonin’s importance for regulating eye processes, particularly when “pressure homeostasis” is involved. Writing in Progress in Retinal and Eye Research, scientists with the University Complutense of Madrid, Spain, explained:

“Glaucoma, the most prevalent eye disease, also known as the silent thief of vision, is a multifactorial pathology that is associated to age and, often, to intraocular hypertension (IOP). Indeed IOP is the only modifiable risk factor and as such medications are available to control it; however, novel medications are sought to minimize undesirable side effects.

Melatonin and analogues decrease IOP in both normotensive and hypertensive eyes. Melatonin activates its cognate membrane receptors, MT1 and MT2, which are present in numerous ocular tissues, including the aqueous-humor-producing ciliary processes.

Melatonin receptors belong to the superfamily of G-protein-coupled receptors and their activation would lead to different signaling pathways depending on the tissue … the current work highlights the important role of melatonin and its analogues in the healthy and in the glaucomatous eyes, with special attention to the control of intraocular pressure.”

Further, the effect of melatonin on intraocular pressure has been known for decades. In 1988, researchers with Oregon Health Sciences University exposed subjects to bright light, in order to suppress serum melatonin levels, and then supplementing with melatonin to gauge its effect on intraocular pressure.

A significant connection was found:

“Our data suggests that during the period of melatonin’s greatest levels in the serum, IOP is lowest. All subjects had maximum pressures form 4 p.m. to 6 p.m. and most subjects had minimums from 2 a.m. to 5 a.m. In experiment one, bright light suppression of melatonin secretion attenuated the early morning fall IOP. This was statistically significant at suggesting that melatonin is involved in lowering early morning IOP.

In experiment one, there was only partial suppression of melatonin production with bright light and consequently there was no significant difference in IOP between subjects exposed to dim light and bright light. However, administering 200 micrograms of melatonin orally caused a significant decrease in IOP. Intraocular pressure remained low for approximately four hours after the last dose.”

Melatonin appears to have far-reaching effects on eye health, even beyond glaucoma. Cataracts, for instance, are associated with oxidative stress, and research suggests melatonin counteracts oxidative damage in the lens and may be a “potential therapeutic agent for cataract prevention/management.”

Melatonin may also be useful for neurovascular age-related macular degeneration (AMD), which is characterized by abnormal angiogenesis in the retina and leads to severe vision loss in more than 90% of those affected. The compound inhibits endothelial progenitor cell angiogenesis and neovascular AMD.

According to a study published in the journal Cells:

“The promotion or inhibition of angiogenesis is part of the homeostatic balance, with positive and negative effects outside the optimum range. Melatonin influences this balance, with evidence from several clinical research investigations demonstrating that this hormone has antiangiogenic effects in cancer and chronic ocular diseases.”

Animal studies also suggest that melatonin protects the retina in dry AMD, while anecdotal reports suggest “favorable” experiences among adults with AMD who supplemented with melatonin.

One study suggested melatonin in a dose of 3 to 20 milligrams at bedtime may be useful for controlling dry AMD.

There’s a mitochondrial component as well, as impaired mitochondrial biogenesis is found in human retinal cells affected by AMD — and melatonin is a potential treatment. Researchers explained in Expert Opinion on Therapeutic Targets:

“During aging, insufficient free radical scavenger systems, impairment of DNA repair mechanisms and reduction of mitochondrial degradation and turnover contribute to the massive accumulation of ROS [reactive oxygen species] disrupting mitochondrial function. Impaired mitochondrial function leads to the decline in the autophagic capacity and induction of inflammation and apoptosis in human RPE cells affected by AMD.”

Importantly, they noted, “The effect of melatonin on mitochondrial function results in the reduction of oxidative stress, inflammation and apoptosis in the retina; these findings demonstrate that melatonin has the potential to prevent and treat AMD.”

In the human body — aside from having direct antioxidant effects — melatonin stimulates the synthesis of glutathione and other important antioxidants like superoxide dismutase and catalase.

Melatonin increases glutathione through a genomic effect on the enzyme that regulates the synthesis of gamma glutamylcysteine synthetase, the rate limiting enzyme in glutathione synthesis. Melatonin activates that enzyme.

Glutathione tends to be found in high concentrations in cells, although some is also found in the extracellular space and the mitochondria. Melatonin’s antioxidant effects are diverse but include preventing free radical generation by enhancing the efficiency of the electron transport chain so fewer electrons leach onto oxygen molecules to generate super oxide antiradical.

Melatonin also has antiviral and anti-inflammatory effects, and more than 140 scientific studies suggest it’s a useful agent for treating SARS-CoV-2, according to research published in Cellular and Molecular Life Sciences.

One reason why melatonin works as an anti-COVID-19 agent is due to its role against sepsis (blood poisoning). Melatonin has prevented death in newborns suffering from severe bacterial sepsis

and also appears to reverse septic shock symptoms by:

• Decreasing synthesis of proinflammatory cytokines

• Preventing lipopolysaccharide (LPS)-induced oxidative damage, endotoxemia and metabolic alterations

• Suppressing gene expression of the bad form of nitric oxide, inducible nitric oxide synthase (iNOS)

• Preventing apoptosis (cell death)

Melatonin also plays an important role in cancer prevention, with “significant atoxic, apoptotic, oncostatic, angiogenetic, differentiating and antiproliferative properties against all solid and liquid tumors.”

It exerts “both direct and indirect anticancer effects,”

in part due to its antioxidant and immunomodulatory effects. Melatonin is also thought to be important for brain, cardiovascular and gastrointestinal health.

For certain eye conditions, there may be benefits to supplementing with oral melatonin. However, it’s also a good idea to optimize your body’s own production, which you can do naturally. Optimizing melatonin production begins with getting enough bright sunlight during the day since this helps to set your circadian clock.

Aim for at least 15 minutes of sunlight in the morning hours helps to regulate the production of melatonin, dropping it to normal daytime levels, so you feel awake during the day and sleep better at night. Ideally you should have sunlight on your bare skin as that will help the near IR in the sunlight activate your mitochondria to produce melatonin. About 95% of your melatonin is produced this way which is why you want the sunlight on your skin.

As evening approaches and the sun sets, you’ll want to avoid artificial lighting. Blue light from electronic screens and LED lights is particularly problematic and inhibits the production of melatonin. If you do need lighting, use incandescent light bulbs, candles or salt lamps.

The blue light from electronic screens can be counteracted by using blue blocking software or wearing blue blocking glasses. You should also sleep in complete darkness at night, as even light that shines through closed eyelids can suppress melatonin.

If your bedroom isn’t pitch-black at bed time, consider wearing a sleep mask.

Engaging in stress-reducing activities, such as stretching or meditation, before bed may also be useful. This is because the release of melatonin is dependent on the release of another hormone, norepinephrine.

Excess stress, and the resulting release of cortisol, will inhibit the release of norepinephrine and therefore the release of melatonin.

So in addition to stress-reduction techniques, try to limit stressful activities — like work projects — in the evening hours.

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Disclaimer: The entire contents of this website are based upon the opinions of Dr. Mercola, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked.

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. The subscription fee being requested is for access to the articles and information posted on this site, and is not being paid for any individual medical advice.

If you are pregnant, nursing, taking medication, or have a medical condition, consult your health care professional before using products based on this content.