Study: Lutein (1990s, 2002, 2004) and Macular Degeneration
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Researchers found that carotenoids, lutein in particular, help protect against development of macular degeneration. With higher levels of carotenoids in the blood stream, a higher antioxidant index, and higher levels of micronutrients in the blood, AMD risk is lowered, especially for wet macular degeneration - the most severe form of the conditions. These findings support the theory that sunlight's damaging UV radiation is a contributing cause of macular degeneration and that carotenoids.
Researchers: The Eye Disease Case-Control Study Group
Published: Antioxidant Status and Neovascular Age-Related Macular Degeneration, Archives of Ophthalmology, January, 1993
Researchers found that consumption of 6mg daily lutein was associated with a 57% decreased in the risk of developing macular degeneration.
Researchers: Seddon, J.M., U.A. Ajani, et al.
Published: Dietary carotenoid, vitamins A, C, E, and advanced age-related macular degeneration, Journal of the American Medical Association, 1994.
In a small pilot study researchers looked at macular pigment density. This is important because pigment density is, in turn, correlated to risk of macular degeneration. They found that macular pigment density increased in 2 subjects who were given 30mg free lutein daily for four and a half months. Macular pigments protect the retina from the damaging effects of blue light and consequently may protect against macular degeneration. Supplementing with 30mg daily lutein brought about a 10-fold increase in lutein levels in the blood in the first 10 to 20 days.
Researchers: Landrum, et al.
Experimental Eye Research, July, 1997
A larger study also looked at macular pigment density. Researchers found that macular pigment density is positively correlated with lutein and zeaxanthin in the blood. Subjects were given about four times the lutein and two to three times the zeaxanthin as in a normal healthy diet. 77% of the patients experienced increases in macular pigment density.
Raising macular pigment density in patients reduces the likelihood that the patient's eye condition will advance to the advanced wet macular degeneration, also known as choroidal neovascularization since there is substantial evidence that macular pigment protects the retina and retinal pigment epithelium against light damage.
Researchers: B.R. Hammond, et al.
Published: Dietary Modification of Human Macular Pigment Density,Investigative Ophthalmology & Visual Science, August 1997
This paper discussed the risk factors, including the role of lutein in protecting the eye from the damaging effects of the sun's light and thus in lowering the risk of developing macular degeneration. They noted that Low levels of lutein in the eye are correlated with higher risk of development of macular degeneration. They note that it has been known for a long time that carotenoids protect against photo-oxidation in plants from damage by blue light, which supports creation of free radicals in the retina. The yellow pigments in the macular pigment counter this damage.
They also actively protect the macula's nerve tissue from the damage, perhaps by passively by shielding tissues behind the outer layer of the eye from excessive blue light.
The researchers concluded that long-term lutein supplementation could result in a significant increase in the level of pigmentation within the macula. In evaluating tissues from human donor eyes, both controls and those diagnosed with AMD they found that AMD eyes had on average approximately 30% less of the total carotenoids found in the controls. The difference in amounts of pigments is not only in the macular area of the retina - indicating that lowered levels of pigment are not a result of degeneration, but more likely a contributing cause.
When subjects were given 30mg of lutein per day the levels of lutein in the blood raised 10-fold within the 1st week and remained high.
Macular pigmentation increase appears to-be a slow process--this amounted to a 15% increase in the pigment level after 72-days of lutein supplementation. A relationship has been established between blood levels of lutein and corresponding increases in the concentration of lutein in the macular of the human eye.
Author: J.T. Landrum, et al
Published: The Macular Pigment: A Possible Role in Protection from Age-Related Macular Degeneration, Advances in Pharmacology, 1997, Volume 38, Pages 537-556.
Another study addressed increasing lutein-rich foods in the diet to protect vision.
Resarchers found that patients experienced benefits in vision quality by increasing lutein-rich foods such as dark leafy greens in their diet.
The diets of 15 dry macular degeneration patients were supplemented with an additional five ounces of sautéed spinach 4-7 times weekly. At the beginning of the study the patients were measured with standardized tests of visual acuity in low light, low-contrast, and recovery from glare. Follow-up testing occurred from 2 to 12 months after the study began.
After 90 days the researchers saw improvements in visual acuity and marked improvements in vision were often detected in follow-up tests, even though patients did not notice changes. Partial or complete resolution of metamorphopsia (distorted vision) and scotomas (blind spots) was reported in seven of eight applicable cases.
The conclusion was the treatment of macular degeneration through diet should receive more attention because it is simple, inexpensive and may apply to a broad range of macular degeneration-related problems.
Lutein and zeaxanthin are carotenoids found in leafy green vegetables such as spinach and kale and are concentrated in retinal macular pigment. Concentrations accumulate when those foods are included regularly in the diet.
Researchers: Dr. Stuart Richer, et al, Atlanta
Presented: resented at Southern Council of Optometrists 1999 annual meeting,
While most research has been on patients with the dry form of macular degeneration, these researchers did a controlled study with 72 patients with the wet form of macular degeneration (neovascularization) and 60 controls. They investigated consumption of antioxidants through diet, and other risk factors for AMD such as smoking, genetics, and exposure to sunlight.
They calculated antioxidant intake based on accepted practices as described in the Framingham Eye Study of the late 70s.
Consistent with earlier research, they found low intake rates for antioxidants generally and lutein specifically. The incidence of AMD in patients was twice as high when they had low rates of consuming antioxidants, especially lutein.
Researchers: E.L. Snellen, et al
Published: Neovascular age-related macular degeneration and its relationship to antioxidant intake., Acta Ophthamologia Scandanavica, August, 2002
Singapore Polytechnic researchers tested a group of seven older subjects with early stage AMD, and six subjects of the same age with healthy eyesight. Each subject received 10 mg of lutein supplements daily for 18 to 20 weeks.
Macular pigment optical density (MPOD low density is considered a risk factor) and blood plasma concentrations of lutein were measured before and after the study. The MPOD average increased significantly in both groups as lutein levels rose. Researchers concluded both a diseased macula may accumulate and synthesize lutein effectively, and people with healthy macula gain benefits from lutein as well.
Researchers: Singapore Polytechnic
Published:Journal Experimental Eye Research, July, 2004
In another 2004 study researchers studied 90 subjects with dry AMD who were divided into three groups and randomly assigned to receive 10 mg of lutein daily, or 10 mg of lutein combined with other nutrients that are known to enhance vision health (such as bilberry, zinc, quercetin, N-acetylcysteine, and others), or a placebo.
Several measurements were taken over the course of a one year test period. Changes in macular pigment optical density (low density is a risk factor) were recorded; contrast sensitivity was evaluated; and visual perception was assessed with eye chart exams.
At the end of the trial, the researchers found clear improvements in both the lutein and the lutein-plus-nutrients group, but no noteworthy changes in the placebo group. Even those subjects who had advanced AMD showed improvement with the additional lutein intake. Larger and longer studies are needed to confirm the findings.
Researchers: Department of Veterans' Affairs, Medical Center Eye Clinic in Chicago
Published: April 2004 issue of the journal Optometry