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Studies shed light on lutein’s
importance to vision
By
Laszlo Dosa
in Ft. Lauderdale
Mother was probably right when she insisted that we eat plenty of
spinach and similar leafy vegetables even if she did not know that
they are a rich source of lutein. That anti-oxidant vitamin, actually
a plant pigment, is a member of the carotenoid family and, along
with zeaxanthin, is an important nutrient that makes up the pigment
found in the macula.
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According
to reports presented at the annual meeting of the Association for
Research in Vision and Ophthalmology, emerging epidemiologic evidence
suggests increased lutein intake may be associated with therapeutic
effects on macula pigment optical density (MPOD) and possibly vision
in atrophic age-related macular degeneration (AMD).
Emily Chew MD, of the US National Eye Institute, conducted a study
to evaluate the association of varying doses of oral supplementation
of lutein with the plasma levels of lutein in people over the age
of 60 with and without AMD.
In an interview with EuroTimes, Dr. Chew noted that while little
is known about the effect of lutein intervention on AMD, there is
scientific information regarding its importance in the normal structure
and function that may explain why it is needed.
"The importance of lutein is that it is not made in animal
tissue. We have to ingest it. It is highly concentrated in the eye
and it needs to be replenished. The greatest sources of lutein are
the green leafy vegetables, such as spinach, collard greens and
kale."
It is known that lutein acts as a sunscreen in plants, a major filter
of ultraviolet radiation. In humans, the Eye Disease Case Control
Study has determined that higher serum levels of carotenoids, especially
lutein and zeaxanthin decreased the risk of AMD by 50-70%, suggesting
a possible role for them in the treatment for age-related macular
degeneration.
The main goal of Dr. Chew’s study was to determine what would
be a safe dose of lutein for humans. There are lutein supplements
that one can buy in the store but there are no clinical trial data
about their effect. Only observational data are available and all
that shows is that "eating a lot of spinach and kale is always
good for you; you probably cannot overdose."
The study enrolled 45 patients ranging in age from 60 to 91 years.
Fifteen had small drusen, 15 had large drusen, and 15 were diagnosed
with advanced AMD. The patients received one of three daily oral
doses of lutein -- 2.5 mg, 5 mg, and 10 mg -- for six months. Patients
then continued to take lutein for another six months.
The researchers measured serum levels of lutein at baseline, and
1, 3, 6, 9, and 12 months. Patients underwent an eye exam and a
heterochromatic flicker test of the MPOD at each visit. Visual acuity
remained essentially unchanged during the six-month dosing period.
"We found at 10 milligrams a four-fold increase in serum levels.
We also know that patients with or without macular degeneration
can absorb the lutein. There was always a concern that people with
AMD could not take it in, but we found that they can. The population
at large, regardless of the macular degeneration status, can take
the supplement and have an elevation in the serum levels, which
is important," Dr. Chew said.
The study did not yield any data on the effect that lutein supplementation
on existing AMD. However, each of the patients responded uniformly
and flicker estimates of MPOD were observably lower in the end stage
AMD group compared with the others. The study showed no large changes
in estimated macular pigment density within or between groups during
the supplementation.
Stuart P. Richer, OD, PhD, suggests that perhaps if Dr. Chew had
followed her patients in the 10 milligram group for a longer period
of time, she might have seen a clinical effect. Dr. Richer conducted
a retrospective chart review that looked at the effect the stage
of macular degeneration has on MPOD in patients with early, moderate
and advanced disease.
Dr. Richer evaluated the retinal disease stage of the Age Related
Eye Disease Study (AREDS) of the National Eye Institute versus the
MPOD/visual function survey in a subset of patients in a Department
of Veteran Affairs study. In the AREDS study, the patients were
divided into different stages of the disease, based on the characteristics
of the fundus.
"We found that we were able to see improvements in macular
pigment optical density enhancement over a one year period in all
three stages with 10 milligrams of non-esterified lutein intake,"
he told EuroTimes.
Dr. Richer and colleagues studied 35 mm retinal colour slides of
60 primarily male veterans with atrophic AMD who were assigned according
to their AREDS stage by a masked retinal specialist into two treatment
groups. One group received 10 mg non-esterified lutein administered
orally as capsules, while the control group was given maltodextrin
placebo. The researchers monitored MPOD, glare recovery and contrast
sensitivity over a one year period.
"We were able to see enhancement of macular pigment optical
density in all stages of macular degeneration with oral supplementation.
And this was also reflected in improved glare recovery values. Secondly,
we were also able to see enhancement of contrast sensitivity, even
in patients with advanced macular degeneration," Dr. Richer
reported.
The results showed that lutein supplementation enhanced MPOD in
AREDS geographic stages II through IV and quickened glare recovery
independent of AREDS retinal stage. Lutein supplementation had no
significant effect on contrast sensitivity for AREDS in stages II
or III. However, the supplement did appear to improve contrast sensitivity
at three of four spatial frequencies in geographic stage IV of advanced
disease.
Emily
Chew, MD
Deputy Director
Division of Epidemiology and Clinical Research NEI
echew@nei.nih.gov
Stuart P. Richer, OD, PhD
North Chicago VA Medical Center
Stuart.Richer@med.va.gov
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