How do Nutritional Supplements Benefit Eye Health?
admin March 7th, 2007
April 2004
Much is being written in the press about biological, chemical and
genetic breakthroughs aimed at the treatment and cure of a wide range
of conditions.
The main thrust has been toward development of patentable drugs. The
results have been less than dramatic. Conventional medicine's inability
to cure, or even prevent, the most debilitating ocular diseases like
age-related macular degeneration, glaucoma and cataract, continues to
spur both interest and research in the science of nutritional and
herbal supplementation.
Multiple clinical studies here and abroad report strong evidence that
antioxidant vitamins, carotenoids and herbal phytochemicals can
significantly help lower the risk and slow the progression of
age-related macular degeneration, cataract formation and glaucoma in
significant numbers of patients. Interestingly though, many competing
studies report that these positive reports are not proof enough and
suggest that the public should wait until pharmaceuticals are available
for these ills.
The American public is not satisfied with the nay-sayers, and the
conflicting evidence has not reduced their curiosity about nutritional
therapy for eye health, nor has it hindered sales of nutritional
products aimed at reducing the risk of ocular disease. Annual sales of
nutritional supplements continue to grow at impressive rates.
The question remains then, do nutritional supplements really work?
With the publication in October 2001 of the multi centered Age Related
Eye Disease (ARED) study, sponsored by the National Eye Institute,
American doctors stopped openly questioning the validity of such
clinical studies. Despite the questionable methodology of the ARED
study, the professional public accepted its conclusions, and now
physicians are joining other "Alternative" practitioners in endorsing
nutritional supplements for a variety of conditions. (1)
The ARED study used a high-dose antioxidant combination of 500 mg
Vitamin C, 400 IU Vitamin E, 15mg beta-carotene, 80 mg zinc, and 2mg
copper daily for six years. That this formula slowed the progress of
age-related macular degeneration (AMD) was a pleasant surprise to the
medical community.
The positive results of the ARED study convinced many ophthalmologists
that they should be prescribing the vitamin combination to their
patients who fit the study's criterion. Further confirmation of
conventional medicine's about-face on the issue of efficacy of vitamin
and nutritional supplements in preventing degenerative disease was the
announcement by the AMA last year that every American should be taking
multivitamins to prevent all types of diseases.
Vitamin C, taken as a separate supplement, has been shown in several
studies to slow the progression of cataracts. A study from Tufts
University and Harvard Medical School found that women who took Vitamin
C supplements for at least ten years had a 60 percent lower risk of
developing nuclear cataract than those who consumed lower levels in
normal diets. (2)
Scientists do not all agree about the results of nutritional clinical
studies (particularly if it wasn't done in their own institution), some
questioning the methodology or accusing other investigators of drawing
conclusions with inadequate data.
Observational research has shown that the carotenoids lutein and
zeaxanthin found in a variety of fruits and vegetables and ocular
supplements may protect against AMD. Several carefully documented
clinical trials have shown that when levels of these carotenoids are
elevated in the serum the risk for developing macular degeneration is
reduced. But still, some physicians are skeptical, and want more
definitive proof. (3)
A number of observational studies have suggested a positive association
between antioxidant intake and increased neurovascular support and
reduced glaucoma risk. Some of these antioxidants are found in complex
combinations in herbs like ginkgo, bilberry and other plants. Ginkgo
has been shown to possess antioxidant properties that help increase
blood circulation in the optic nerve with resulting improvement of
pre-existing visual field damage. (4) Bilberry and other plants contain
the antioxidant compound resveratrol and anthocyanosides that can
prevent oxidative damage to the retinal pigment. (5)
Some physicians remain skeptical, but the evidence is growing, and one
thing remains sure: science is clearly showing that nutritional therapy
can slow or reverse degenerative conditions like macular degeneration,
cataracts and glaucoma. With an estimated 8 million people at risk for
developing advanced AMD in the United States, more than 300,000 have
the chance of avoiding the disease and its vision loss if they are
given proper supplements over the next five years.
References:
1) Age related Eye Disease Study Research Group. A
randomixed,placebo-controlled, clinical trial of high-dose
supplemtnetration with vitamins C and E, beta carotene, and zinc for
age-related macular degeneraion and vision loss: AREDS report no.8,Arch Ophthalmo 2001;119:1417-36.
2) Jacques PF,Chylack LT, Hankinson SE, et al. Long-term nutrient
intake and early age-related nuclear lens opacities. Arch Ophthalmol.
2001;119:7:1009-19.
3) Mozaffarieh M, Sacu S, Wedrich A. The role of the carotenoids,
lutein and zeaxanthin, in protecting against age-related macular
degeneration: A review based oon controversial evidence. Nutr J.
2003;2:1:20.
4) Quaranta L,Bettelli S, Uva M, et al. Effect of Ginkgo biloba
extract on preexisting visual field damage in nomal tension glaucoma.
Ophthalmology. 2003;110:2:359-62) (Ritch R, Potential
role for Ginko biloba extract in the treatment of glaucoma. Med
Hypotheses.
2000;54:2:221-35.
5) Roy S, Khanna S Alessui Hm et al. Anti-angiogenic property of edible berries. Free Radic Res. 2002;36:9:1023-31.
© 2004 by Spencer Thornton, M.D.. All rights reserved.