Lutein and its isomers zeaxanthin and meso-zeaxanthin is a kind of macular pigment accumulated in the human retina. Do you know what are lutein benefits and side effects?
They cannot be synthesized in mammals, they must be obtained from the diet, and then distributed to various tissues, especially the retina, and have the following physiological functions:
- The most important antioxidant component in the macular area of the retina (the most elite area that produces vision) can inhibit free radicals formed during the photoreceptive process.
- Formation of macular pigment, filtering harmful short-wave blue light (can absorb 40% to 90% of incident blue light).
- Improve visual function (achieved by reducing color difference and improving color contrast), improving glare disability and photostimulation recovery period.
What are lutein’s benefits and side effects?
Table of Contents
- What is lutein?
- What are the benefits of lutein?
- 1. Lutein beneficial cognitive function
- 2. Lutein benefits age-related macular degeneration
- 3. Lutein is good for bone health
- 4. Lutein improves dark adaptability
- 5. Lutein increases the frequency of physical activity
- 6. Lutein benefits diabetic retinopathy
- 7. Lutein improves stress resistance
- 8. Lutein reduces the incidence of cancer
- 9. Lutein improves visual adaptability
- 10. Lutein is good for intellectual performance
- 11. Lutein reduces the incidence of cataract
- 12. Lutein prevents cardiovascular and metabolic diseases
- 13. Lutein enhances visual recognition
- 14. Lutein improves skin aging
- 15. Lutein relieves visual fatigue
- Are there any side effects of lutein?
- Safety precautions
- The best food source of lutein?
- Natural food sources of lutein
- The recommended dosage of lutein supplement (how to eat)
- The three main factors affecting the absorption of lutein and zeaxanthin?
- Where can I buy the lutein (recommended)?
What is lutein?
Lutein is a fat-soluble pigment and belongs to the family of carotenoids. There are more than 600 kinds of carotenoids in nature, 30-50 of which are part of the normal human diet.
Carotenoids can be divided into two categories: non-polar carotenes (carotenes, such as β-carotene and lycopene) and polar xanthophylls (xanthophylls, such as lutein and zeaxanthin).
Since the biosynthesis of lutein only occurs in plants, algae, bacteria, and certain fungi, the main intake of human lutein depends on diet or supplements.
Studies have shown that for every 10% increase in lutein intake in the diet, the concentration of lutein in the serum increases by 2% to 4%.
What are the benefits of lutein recommended?
1. Lutein beneficial cognitive function
As people age, many aspects have changed, including physical and psychological. Some changes may be good, some are not.
Cognitive functions as a normal aging process have been well proven in the scientific literature.
Some cognitive abilities, such as vocabulary, are resilient to brain aging and may even improve with age. Other abilities, such as conceptual reasoning, memory, and processing speed, gradually decline over time.
A Systematic Review (including 5 randomized controlled trials) pointed out that lutein supplementation (daily dose of 10 mg for 12 months) has the effect of improving some cognitive function indicators, such as visual episodic memory) and inhibition.
2. Lutein benefits age-related macular degeneration
Age-related macular degeneration is a progressive visual impairment that is associated with neurodegeneration of retinal pigment-photoreceptor cells. Common symptoms are blurred central vision, deformation, and decreased vision.
In developed countries, age-related macular degeneration is the main cause of central vision loss, and age is the most powerful predictor. Although it rarely occurs in people under the age of 50, compared with patients aged 65 to 74, Patients over 75 years of age have more than tripled their risk.
A Meta-analysis (including 9 randomized controlled trials, a total of 855 patients with macular degeneration) pointed out that supplementation of lutein or related compounds (10 or 20 mg per day for more than 6 months) can help improve Macular pigment density (MPOD) and improve visual acuity and contrast sensitivity.
*Conclusion: Supplementation of lutein or related compounds is positive for macular degeneration, but it is limited by the high heterogeneity between studies and needs to be confirmed by more long-term large-scale trials.
3. Lutein is good for bone health
Skeleton is a dynamic tissue with structural and metabolic functions. Structurally, bones protect vital organs from mechanical forces, provide leverage to transfer force from one area of the body to another, and provide attachment sites for muscle-driven movements.
From a metabolic point of view, bones contain a large number of blood cell types and are the largest calcium stores in the body.
Sufficient nutrition, mechanical load, hormonal status, and genetic factors can maintain bone homeostasis. The interruption of any of these factors may have harmful consequences.
An observational study (of 63 healthy adults) pointed out that although serum lutein and zeaxanthin concentrations were not related to bone mass, macular pigment density (MPOD) was significantly associated with bone density in the proximal femur and lumbar spine.
4. Lutein improves dark adaptability
Dark adaptation refers to the process in which the eyes become more sensitive to light when the light is reduced.
For example, when you enter a dark area from a well-lit place (for example, to watch a movie), it will be completely dark at first, but it will start to be clear after a while.
In clinical practice, dark adaptation is a method of measuring visual function, which has been proven to be one of the symptoms of retinal diseases (such as macular degeneration, macular edema, retinitis pigmentosa, diabetes, and hypertensive retinopathy), in addition to Vitamin A deficiency, light exposure, smoking, aging, and tissue hypoxia can also cause a decrease in dark adaptation.
Two observational studies have found that the concentration of macular pigment is related to dark adaptation, and those with higher concentrations obviously have better dark adaptation ability.
5. Lutein increases the frequency of physical activity
Physical activity is defined as any physical activity that causes energy expenditure in skeletal muscles. According to the recommendation of the American College of Sports Medicine, in order to promote and maintain health, all healthy adults require 5 weeks per week. At least 30 minutes of moderate-intensity aerobic exercise, or at least 20 minutes of high-intensity aerobic exercise 3 days a week.
Lack of exercise is an adjustable risk factor for cardiovascular disease and various chronic diseases, including diabetes, cancer (colon cancer and breast cancer), obesity, hypertension, bone and joint diseases (osteoporosis and osteoarthritis), and depression.
A Systematic Review (including 17 studies) pointed out that higher lutein levels may be related to more frequent physical activity, which may help improve physical activity and reduce the risk of chronic diseases.
The underlying mechanism may be related to lutein crossing the blood-brain barrier, regulating the functional characteristics of neurons, and affecting communication between neurons.
6. Lutein benefits diabetic retinopathy
Diabetic retinopathy is currently the number one cause of blindness in the 20 to 60-year-old population. During the 10-year period when diabetes begins to develop, patients with type 1 and type 2 diabetes have a 100% and 60% chance of developing retinopathy. The blinding rate is 20 times that of the average person.
Although early detection, blood sugar/blood pressure, and blood lipid control can reduce the risk of disease, it is often difficult to achieve clinically.
A randomized, double-blind, placebo-controlled trial (a 31-week, 31 non-proliferative diabetic retinopathy patients) pointed out that compared with placebo, lutein supplementation has the effect of improving visual function (especially low space Frequency contrast sensitivity).
7. Lutein improves stress resistance
Psychological Stress refers to the physical and psychological reactions caused by all external stimuli. Although benign stress will bring about growth, extreme or repeated stress events are often related to cardiovascular diseases, immune diseases, mental disorders, and cancer.
A randomized double-blind controlled study (12-month, 59 healthy adults) pointed out that the intake of lutein and zeaxanthin can help to improve psychological stress and serum cortisol.
*Comment: Oral lutein may have the effect of reducing psychological stress and improving physical and emotional health, but it is limited by the number of samples and more research is still needed to confirm.
8. Lutein reduces the incidence of cancer
About 30% of cancers are related to five major behavioral and dietary risks, such as high body mass index, low fruit, and vegetable intake, lack of physical activity, smoking, and drinking.
Compared with residents of Western countries, Asians are 25 times less likely to suffer from prostate cancer and 10 times less likely to develop breast cancer. However, as the lifestyle is gradually westernized, the incidence of these cancers has increased significantly.
A case-control study (targeting 521 women) indicated that blood carotenoids (α-carotene, β-carotene, lycopene, lutein/zeaxanthin) concentrations were higher and breast cancer occurred less The rate is related.
Another meta-analysis (including 10 studies, 1958 cases of esophageal cancer, 4529 cases of the control group) pointed out that carotenoids (beta-carotene, alpha-carotene, lycopene, beta-cryptoxanthin), Lutein and zeaxanthin, the lower the risk of esophageal cancer.
Another case-control study (subjects were 1993 colorectal cancer patients and 2,410 control groups) pointed out that eating more foods rich in lutein (including spinach, broccoli, lettuce, tomatoes, oranges and orange juice, carrots, celery, and green vegetables can greatly reduce the risk of colorectal cancer.
9. Lutein improves visual adaptability
Disability glare refers to the short-term loss of visual accuracy caused by uncontrolled light such as high intensity in the visual range. Glare not only easily causes eye fatigue, affects reading and learning, but may also cause traffic accidents.
In addition, photostress recovery refers to the time it takes for the eyes to recover normal vision after encountering strong light, and aging and abnormal visual cells may cause recovery time to increase.
Several studies have found that by supplementing lutein and zeaxanthin (6 mg to 12 months, 12 mg per day) can significantly increase the density of macular pigment, in addition to improving the transient glare disability caused by strong light Phenomenon, and help reduce the time required for the recovery of light stimuli.
10. Lutein is good for intellectual performance
There are many definitions of intelligence, including but not limited to abstract thinking, understanding, self-awareness, communication, reasoning, learning, emotional knowledge, and ability to plan and solve problems.
And intelligence is not just used to learn book knowledge, academic skills, or examination skills, it reflects a broader and deeper ability to understand our surroundings.
Intelligence can grasp or understand things, or figure out what to do, and is often regarded as a predictor of academic achievement, job performance, and income.
An observational study (114 adults with a BMI ≥ 25 kg/m²) pointed out that regardless of the body fat rate, subjects with a higher density of macular pigment (referred to as lutein molecules in the retina) clearly have better intelligence Level (intelligence is measured by Kaufman Brief Intelligence Test).
In addition, this study further found that the effect of macular pigment on intelligence levels, especially fluid intelligence is the most significant.
*Fluid Intelligence: Refers to the ability to solve, create, and respond flexibly to challenges in new situations without prior knowledge.
11. Lutein reduces the incidence of cataract
A cataract is a disease caused by the denaturation of water crystals. It will cause the originally clear crystals to become cloudy, which will affect the light entering the retina and cause vision loss.
Compared to other eye diseases (such as glaucoma, macular degeneration, and diabetic retinopathy), cataract is the main cause of blindness in the Asian population over 40 years old.
A meta-analysis of literature indicates that (including 8 population observation studies), those with higher concentrations of lutein and zeaxanthin in the blood can help reduce the risk of nuclear cataracts (ranges are 27% and 37%, respectively), However, there is no obvious association with other forms of cataract (such as cortical and subcystic cataracts).
Another comprehensive analysis of the literature on dose-response also pointed out (including 6 prospective generational studies, 41,999 participants), intake of more lutein and zeaxanthin from the diet can reduce the 25% The incidence of nuclear cataract.
The underlying mechanism is related to the antioxidant properties of lutein, which can remove peroxides, hydroxyl radicals, lipofuscin, and protect the cell membrane from ultraviolet and blue light damage.
*Nuclear cataract is the most common type of senile cataract.
*Conclusion: Appropriate intake of lutein can help reduce the incidence of some types of cataract, but considering the possible deviations (confounding and bias) of the included studies, it needs to be further confirmed by more controlled intervention studies.
12. Lutein prevents cardiovascular and metabolic diseases
Cardiovascular and related metabolic abnormalities can be said to be a major cause of various health problems. People with metabolic abnormalities in the new generation are three times more likely to suffer from cardiovascular disease than ordinary people. Related cardiovascular risk factors include high blood pressure and high cholesterol, high blood sugar.
A large-scale systematic review (including 71 studies with a sample size of 387,000) and meta-analysis indicated that the intake of more lutein or the concentration of lutein in the blood was higher, helps to achieve the following state (data found after mathematical analysis).
- Reduces the risk of coronary heart disease (a cardiovascular atherosclerotic disease that causes angina and myocardial infarction) by 12%
- Reduce the risk of stroke by 18%
- Reduces the risk of metabolic syndrome by 25% (a health problem including obesity, blood pressure, blood sugar, and dyslipidemia)
The underlying mechanism is believed to be related to the antioxidant and anti-inflammatory effects of lutein. These two major factors are one of the main causes of cardiovascular disease and metabolic disease.
13. Lutein enhances visual recognition
Modern people’s high 3C dependence often causes premature aging of the eyes. The following phenomena may be typical visual aging, such as narrowing of the visual field, slow response to visual information, difficulty in adjusting the focal length, and poor light adaptability.
In a recent controlled study, it was found that taking lutein and zeaxanthin can increase the visual processing ability (especially the ability to distinguish objects and light sources) by 20%. For driving safety, reading speed, sports performance, and cognitive execution All have significant help.
14. Lutein improves skin aging
Skin aging is a complex physiological process. At present, it is known that it can be divided into endogenous aging (related to genes), which is usually irreversible. The second type is exogenous aging, mainly related to ultraviolet radiation damage, also known as photoaging.
Even though the two aging processes are independent of each other, the molecular mechanism is the same, that is, reactive oxygen damage (cell metabolism will naturally occur), often causing collagen degradation or reduced synthesis.
There are no shortcuts or panacea for anti-aging. The best strategy is through a good lifestyle and antioxidant food.
A double-blind controlled study pointed out that in addition to helping lutein and zeaxanthin to improve overall skin tone and brightness, it can also increase the minimal erythema dose, which may have the effect of whitening and improving skin condition.
The underlying mechanism is related to the antioxidant properties and photoprotective activity of lutein and zeaxanthin, which can reduce the formation of melanin and reduce the damage of harmful light.
15. Lutein relieves visual fatigue
Modern people often can’t work without computers, and mobile phones and tablets are also on the side during leisure, so the eyes often experience discomfort such as acid, numbness, bloating, and pain. These symptoms represent the distress signal sent by the eyes, so After every 30 minutes of concentration, please rest for 5 to 10 minutes to avoid accelerated aging of the eyes.
In a study on visual fatigue, it was found that taking lutein compound (in the experiment, let the subjects do a 2-hour text proofreading, and observe the response after taking lutein) can really reduce the effects of frequent eye use Fatigue discomfort and stress index
Are there any side effects of lutein?
In the known scientific literature, the appropriate amount of lutein is extremely safe. In the 5-year AREDS2 large-scale study, the daily dose is 10 mg. No toxicity or adverse reactions have been found when taking Lutein and zeaxanthin.
The only confirmed side effect is yellowing of the skin of the hands and feet (due to long-term large doses or excessive consumption, also known as carotene), the reason is that the constitution is more sensitive to lutein, and the metabolism is inadequate, causing yellowing of the skin. Thought it was jaundice
1. The safety of using lutein in pregnant women and breastfeeding is unknown, so it is recommended to consume more fruits and vegetables.
2. Patients with Cystic fibrosis often fail to absorb carotenoids in food or supplements, so be careful when using lutein products
3. Concurrent consumption of snacks containing olestra or the use of other carotenoid supplements may reduce lutein absorption.
4. A case study found that a woman with glaucoma ingested lutein (20 mg daily for 8 years with a high lutein diet) for a long period of time, resulting in cases of retinal crystal deposits, And this phenomenon does not affect the patient’s vision, and the crystallization has partially disappeared after discontinuation.
The best food source of lutein?
According to the currently available research, it is found that the bioavailability of lutein from egg yolk is the highest, and the absorption efficiency is several times that of health care preparations and vegetables. The underlying mechanism may be related to fat composition.
Eating an egg a day for 5 consecutive weeks can increase the concentration of lutein and zeaxanthin in the blood by 26% and 38%, respectively.
Another study found that, for 90 consecutive days, ingesting lutein-rich eggs (1 mg per day) had the same effect on increasing the concentration of lutein in the blood as using 5 mg of healthy food.
Natural food sources of lutein
Lutein is found in many foods, like dark green leafy vegetables and fruits: Brussels sprouts, spinach, Chinese kale, broccoli, peas, kiwis, grapes, oranges are rich in lutein if possible Daily intake of 1 bowl of spinach or kale can reach the recommended amount of 6 mg of lutein per day, but it should be noted that these foods should not be cooked for too long, as long as they are cooked, because long cooking will cause nutrients Are lost.
The recommended dosage of lutein supplement (how to eat)
If you don’t eat the fruits and vegetables and eggs mentioned above frequently, or eat out frequently, you can choose nutritious health foods containing lutein to supplement.
The three main factors affecting the absorption of lutein and zeaxanthin?
1. The nature of food: for example, cooking or raw food, although cooking reduces the content of lutein, but compared with uncooked sources, it will increase the bioavailability of lutein.
2. The amount of dietary fat: adding an appropriate amount of fat during cooking, or taking with meals (using health products) can increase the absorption rate.
Where can I buy the lutein (recommended)?
In recent years, food safety problems in various countries have exploded, and it is not healthy but black-hearted products that everyone spends on. Therefore, European and American products with relatively strict quality control have become popular products.
And iHerb.com is a large-scale medical cosmetics e-commerce company in the United States. It has a high satisfaction rate of 97% in the evaluation of Google customers. It provides global home delivery so that you can buy it without risking buying fakes through purchasing high-quality health products.