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Questions les plus fréquentes sur la lutéine
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.
Eye Health
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
health.
Skin Health
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
Cardiovascular Health
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.**
Women's Health
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
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