What is lutein?
Lutein is a carotenoid found abundantly in fruits and vegetables, particularly in dark green, leafy vegetables such as spinach and kale. It is also present in foods such as corn and egg yolks. Lutein is found in nature alongside a smaller amount of a closely related carotenoid called zeaxanthin. Carotenoids are compounds that provide color to plants and act as antioxidants.
What is the function of lutein?
Lutein is an antioxidant that may aid in protecting the eyes and skin from oxidation reactions by quenching free radicals.** Lutein also may act to filter high-energy blue light that can damage the macula, an area in the back of the retina.**
Where is it found in the human body?
Lutein is present in the eye, serum, skin, cervix, brain and breast. Within the eye, lutein is highly concentrated in the macular region of the retina and is dispersed in lesser amounts throughout the entire retina, ciliary iris bodies and lens.
What health conditions may lutein play a protective role in?
Studies have shown that lutein may reduce the risk of age-related macular degeneration.**1,2,3 More recent work suggests that lutein may play a role in helping reduce the risk of cataracts.**4,5,6,7 Emerging science suggests that lutein may also play a role in cardiovascular health 8,9,10,11,12 and skin health 13,14,15,16,17.**
Can your body produce lutein?
No. The human body is unable to manufacture lutein. Consumption of either lutein-containing foods or dietary supplements containing lutein is the only way for your body to obtain it.
How much lutein do I need?
There is no recommended daily intake for lutein. The body of evidence suggests an intake of 6 mg to 20 mg per day. You should consult with your doctor to determine an acceptable dosage level based on your current health status and dietary intake of lutein.
What are “lutein esters?” Are they the same as purified lutein?
Lutein esters are sometimes used in products in place of purified lutein. Lutein esters are chemically different from lutein, and they require enzymatic digestion in the small intestine to allow any lutein to be taken up by the body. Purified lutein is absorbed directly by the body without the need for enzymatic digestion. Products containing lutein esters should identify them as such on the ingredient list or supplement facts panel.
What is age-related macular degeneration (AMD)?
Age-related macular degeneration causes irreversible blindness. It occurs when the cells (rods and cones) in the macula degrade, causing loss of sight in the central part of the field of vision, but leaving peripheral vision intact.
“Dry” age-related macular degeneration
Dry AMD occurs in 90 percent of the reported cases and is characterized by small yellow spots called drusen accumulating behind the macula. It is typically not associated with blindness but with loss of visual acuity. However, if left untreated, it could progress into wet AMD.
“Wet” age-related macular degeneration
Wet AMD derives its name from the tiny, abnormal vessels that grow behind the retina toward the macula that seep fluid into the tissue. As a result, the macula is damaged, leading to the onset of blindness.
How is lutein related to macular degeneration?
Macular degeneration is a condition that may begin to develop as one ages, but usually doesn’t manifest itself until later in life. Macular degeneration is the leading cause of irreversible blindness in the United States for individuals over 65 years of age. By consuming fruits and vegetables in accordance with the current Dietary Guidelines for Americans, you may be achieving an adequate amount of lutein in your diet to decrease the risk of developing this disease..**18** However, consumer statistics show that only 23 percent of Americans eat the recommended amounts of vegetables and fruits daily.**19 Therefore, a dietary supplement or fortified foods and beverages containing lutein may be used as a complement to the diet.
Lutein and zeaxanthin are the principle carotenoids found in the macula. They comprise the macular pigment, a yellow pigment that filters blue light and may protect the macula from free-radical damage.**
What is the macula?
The macula lutea is a small area just two millimeters wide, located in the back of the eye, in the middle portion of the retina. The center portion of the macula is referred to as the fovea, and contains the highest concentration of rods and cones. It is responsible for central vision.
Who is susceptible to age-related macular degeneration?
There are several factors that may increase your risk of developing AMD: age, poor diet, exposure to sunlight, smoking, heredity, gender, race, eye color, alcohol usage and heart disease. For example, individuals with blue or green eyes, seniors, women, smokers and Caucasians are all at higher risk.
What can I do to protect myself from AMD?
While there are factors that you cannot change such as age, heredity and gender, several key risk factors are lifestyle related. Here are some tips: wear sunglasses and a wide-brimmed hat to protect you from direct or reflected sunlight; eat a diet rich in fruits and dark green, leafy vegetables that contain lutein; stop smoking and limit your intake of alcohol, saturated fats and cholesterol.
Can lutein help reduce the risk of cataracts?
The latest progress report from the Beaver Dam eye study, which involves adults from 43-84 years of age, suggests that lutein and zeaxanthin intake may reduce the incidence of cataracts.**20 Lutein and zeaxanthin are the only carotenoids found in the lens.
Chasan-Taber and co-workers conducted a prospective study of 77,466 female nurses 45-71 years old, from 1980 through 1992. The results showed that nurses with the highest intake of lutein and zeaxanthin had 22 percent lower risk of cataract extraction compared to those in the lowest quintile of intake. This study also showed that high intake of spinach and kale, green vegetables rich in lutein, may reduce the risk of cataract extraction.**5 Both spinach and kale are rich in lutein.
In a similar study, Brown and collaborators studied the association between carotenoids (alpha-carotene, beta-carotene, lutein, lycopene, beta-cryptoxanthin and lycopene) and Vitamin A intakes and cataracts extraction in 36,344 male health professionals 45 to 75 years old. Researchers found that men with the highest consumption of lutein and zeaxanthin had a 19 percent lower risk of cataract extraction compared to men with the lowest consumption. Furthermore, among foods high in carotenoids, broccoli and spinach, vegetables rich in lutein, had the strongest association with a lower risk of cataracts.** 4 Again, these vegetables are rich in lutein.
Has lutein been studied in other areas of human health?
In addition to AMD and cataracts, there is scientific research suggesting lutein may perform a positive role in skin, cardiovascular, breast and retinal
How does UVA, UVB, and visible light affect skin health?
Damage occurs to all layers of the skin as a result of environmental exposure. 21 The shorter wavelengths of ultraviolet light, the UVB, have been shown to penetrate only the outermost layers, the epidermis, of the skin. Conversely, the longer wavelengths, the UVA, have been shown to penetrate through the epidermis and into the dermis. Visible light can penetrate the entire depth of the skin. Therefore, light has the potential of doing damage throughout the entire depth of the skin. This damage may be associated with a depletion of the skin's natural antioxidant system. 22
What role does lutein play in skin health?
An emerging area of research is lutein's role in skin health. The mechanism of action in skin is thought to be similar to that in the eye, with lutein protecting the skin by absorbing high-energy wavelengths of blue-light and quenching free radicals that may be produced in the skin after exposure to light and environmental assault. Science shows ingesting lutein from food or dietary supplements may help reduce oxidative damage.
Lutein has been scientifically shown to:
- absorb blue light, 23
- quench the triplet state of photosensitizers, 24-25
- quench singlet oxygen, 25-28 and
- inhibit lipid peroxidation. 29
This list of activities demonstrates the ways that lutein may support healthy skin. Additionally, studies suggest lutein may be effective in helping:
- the skin respond to ultraviolet light-induced cellular proliferation, 17,30
- decrease ultraviolet light-induced inflammation and immunosuppression, 13 and
- inhibit photocarcinogenesis (in at least one animal species).31
Can lutein help reduce the risk of cardiovascular disease?
Interest in the prevention of heart disease by carotenoids stems from the finding in epidemiological studies that persons with higher intakes of fruits and vegetables are at a reduced risk of coronary heart disease and stroke** 32,33. Mediterranean populations have the lowest mortality rate from coronary heart disease in Europe 34. When foods common to the Mediterranean diet were analyzed for carotenoid content, high levels of lutein were detected and correlated well with the relatively high serum levels of lutein found in Greek people 35. The authors of this study theorize this may contribute to the lower mortality rate from coronary heart disease exhibited by this group.
How does lutein protect against cardiovascular disease?
The exact mechanism of lutein’s suggested ability to protect against cardiovascular disease is unknown at this time; however, three studies (collectively known as The Los Angeles Atherosclerosis Study 8) published by Dr. James Dwyer at the University of Southern California suggest that the protective effect of lutein is at least partially due to an antioxidant mechanism.** First, Dr. Dwyer's research indicated that as plasma lutein concentration increased, carotid artery intima-media thickness decreased in women and men. Carotid artery intima-media thickness has been strongly associated with the risk of both coronary heart disease and stroke. Next, he incubated endothelial and smooth muscle cells from human aortas with lutein and found a significant inhibition of the inflammatory response of monocytes to LDL (Low Density Lipoprotein) trapped in the artery wall. Finally, Dr. Dwyer's research found that in mice known to develop severe atherosclerotic lesions, lutein supplementation significantly reduced the size of atherosclerotic lesions in the aortic arch.** In addition, lutein significantly reduced markers of oxidative stress and plasma VLDL+IDL (Very Low Density Lipoprotein + Intermediate Density Lipoprotein) levels.** These results suggest that there may be a positive effect of lutein on the progression of early atherosclerosis.**
What role does lutein play in women's health?
Lutein has been detected both in breast and cervical/ovarian tissue 38,40. Several studies in the past few years have linked carotenoids, including lutein, to lower risk of breast cancer.**36,37,39,40 These studies showed inverse relationships between serum/plasma lutein and risk of breast cancer as well as suppression of cancer cell proliferation in vitro.** The role of lutein in cervical/ovarian tissue has not been defined to this date.
What role does lutein play in infant health?
Other functions of lutein in the body currently being investigated include lutein's role during pregnancy and lactation. Studies have indicated that the level of lutein increases in the plasma throughout pregnancy, although the reason for this has not been defined at this time. Lutein has also been detected in cord blood after delivery and is found in colostrum and mature breast milk. It has been theorized that lutein may be actively secreted into the breast milk. This is based on the finding that the levels of lutein and beta-carotene in the serum are equal, but lutein levels are significantly higher than beta-carotene in breast milk. 42-46