Macular degeneration is a very serious eye disease. It destroys the macula lutea, a small, thin area of the retina responsible for seeing clearly. Positively correlated with increased age is age-related macular degeneration, or AMD. Stargardt macular degeneration is an inherited form and occurs in younger people. Age-related macular degeneration comes in two types: the dry form, called atrophic, and the wet form, called neovascular. Growing evidence indicates Vitamin A can help prevent AMD.
Vitamin A and Stargardt Macular Degeneration
Don't take supplements of vitamin A if you suffer from Stargardt macular degeneration, say University of California researchers. Mutations to a gene known as ABCA4 cause this form of macular degeneration. Their article, published in the September 2008 issue of "Investigative Ophthalmology and Visual Science," says vitamin A can be problematic in cases of Stargardt macular degeneration because this genetic disease can produce a toxin called lipofuscin, which destroys photoreceptors in the eye. Results of their experiments on mice, in which vitamin A was prevented from reaching the eye, showed a reduction in toxic lipofuscin.
Vitamin A and AMD
AMD occurs when deposits of fat and protein accumulate behind the retina. In dry AMD, these deposits eventually destroy sections of macular photoreceptors -- the rods and cones. Symptoms of dry AMD include problems with night vision and reading small print. In wet AMD, these deposits cause blood vessels to push closer to the macula and leak. Wet AMD might completely disable the macula and lead to blindness. A particular form of vitamin A might act as an antioxidant, preventing the buildup of the harmful deposits, or drusen, behind the retina. Vitamin A might help stop damage to the eye both from oxygen and bright light.
Case For Two Carotenoids
The macula of the eye contains only two carotenoids -- lutein and zeaxanthin. These give the macula its yellow color. Carotenoids are a form of vitamin A, which are available in dark green and orange plant sources such as carrots. Eating lutein and zeaxanthin might help prevent age-related macular degeneration, if these nutrients go directly into the macula. Evidence for this theory comes from P.S. Bernstein of the Moran Eye Center at the University of Utah School of Medicine. Bernstein's experiments, discussed in the journal "Acta Horticulturae," August 2009, show that measurable dietary lutein and zeaxanthin do end up in the macula. He says these carotenoids absorb harmful blue spectrum light.
How to Prevent AMD
You can help prevent age-related macular degeneration by taking good care of your eyes. See an eye specialist regularly to detect any changes in the retina. Early diagnosis and treatment of macular degeneration are important. Also, it doesn't hurt to eat foods high in carotenoids. The American Optometric Association recommends leafy varieties of green vegetables, as they are highest in lutein. To get zeaxanthin in the diet, choose vegetables and fruit that are orange and yellow in color. Wear sunglasses when outside or driving to protect your eyes from sun damage. Furthermore, don't smoke, because according to Bernstein, smoking increases your risk of developing AMD.
References
- "Investigative Ophthalmology and Visual Science"; "Accelerated Accumulation of Lipofuscin Pigments in the RPE of a Mouse Model for ABCA4-Mediated Retinal Dystrophies Following Vitamin A Supplementation"; Roxana Radu et al; September 2008
- "Acta Horticulturae"; "Nutritional Interventions Against Age-Related Macular Degeneration"; P.S. Bernstein; August 2009
- "Anatomy and Physiology"; Elaine Marieb, R.N., and Dr. Katja Hoehn; 2008
- American Optometric Association: Lutein and Zeaxanthin
