Preventing AMD Through Nutrition
Age-related macular degeneration commonly referred to as AMD is a disease in which the tissue in the macula deteriorates. The macula is located in the central part of the retina and is responsible for producing sharp central vision. The exact causes of AMD are still unknown although age and heredity appear to be the dominant factors. This condition can result in severely diminished central vision but peripheral vision remains unaffected. In most cases it is impossible to restore the vision loss caused by AMD. Prevention therefore remains the best way to avoid severe vision loss.
Scientific research suggests that smoking obesity or cumulative exposure to sunlight and its harmful ultraviolet rays causes free radicals to form. This increases the risk of damage done to the body. Free radicals are molecules that form as the body processes oxygen and food. If uncontrolled these molecules can cause cellular damage.
Antioxidants & Zinc
Antioxidants ‘absorb’ free radicals before they harm the body. Carotenoids are a type of antioxidant and the two most effective carotenoid antioxidants believed to combat AMD are lutein and zeaxanthin. These two compounds are the primary components of the macular pigment and because of this researchers believe that when present in high amounts the antioxidants can help prevent the progression of AMD. They accomplish this by:
- Filtering harmful blue light that might otherwise reach the retina and damage the macula
- Protecting the retina from damage through antioxidant activity
- Protecting the blood vessels that supply the macula
Although scientific research has not pinpointed when and in what amounts potentially affected people of AMD should actively increase their dietary intake of antioxidants several studies indicate the benefits of lutein and zeaxanthin. According to the Age-Related Eye Disease Study (AREDS) conducted by the National Eye Institute in the United States a combination of vitamin C vitamin E beta-carotene and zinc can reduce the risk of AMD by about 25 per cent. These same nutrients also reduce the risk of vision loss caused by advanced AMD by about 19 per cent. In another study the results suggested that there is a 43 per cent lower risk of developing AMD among people who have high intake levels of carotenoids. Of the people studied those who had the highest intake levels of lutein and zeaxanthin had a 57 per cent lower risk of AMD1
Exact Dosages (from AREDS study)
Vitamin C – 500 mg Vitamin E – 400 IU Beta-carotene – 15 mg Zinc oxide – 80 mg Cupric oxide – 2 mg
As the body produces neither lutein nor zeaxanthin one must obtain them through dietary intake. Consult your eyecare practitioner to determine if you should obtain these carotenoids primarily through an improved diet vitamin supplements or a combination of both. Lutein and zeaxanthin exist mainly in some fruit and vegetables. The following is a list of foods high in these antioxidants. Raw vegetables have a greater nutritional value than cooked vegetables and green vegetables have a higher concentration of lutein and zeaxanthin. The following is a list of vegetables/fruits recommended:
- fresh parsley
- red grapes
- egg yolk
- kiwi fruit
Fatty foods in processed baked goods can cause the progression of AMD according to a study published by The Archives of Opthamology. The research was conducted by Johanna M. Seddon M.D. S.C. of the Massachusetts Eye and Ear Infirmary and her colleagues. They evaluated the associated dietary fat intake and the rates of progression for AMD in a large elderly population at risk for contracting the disease.
261 patients age 60 or older were studied who had some sign of AMD in one eye. These participants had their AMD progression followed for about five years while their dietary fat intake was monitored on a weekly basis.
The study concluded that a progression of AMD can occur from the ability of fatty foods to constrict blood vessels. The findings also noted that fish and nuts reduced the risk of. the disease progressing. Diets rich in meat and dairy also increase the risk but to a lesser extent than processed baked goods.
Possible Side Effects of Nutritional Supplements
The AREDS participants reported few side effects from the treatments. About 7.5 per cent of participants assigned to the zinc treatments – compared with five per cent who did not have zinc in their assigned treatment – had urinary tract problems that required hospitalization. Participants in the two groups that took zinc also reported anemia at a slightly higher rate; however testing of all patients for this disorder showed no difference among treatment groups. Yellowing of the skin a well-known side effect of large doses of beta-carotene was reported slightly more often by participants taking antioxidants.
Those who smoke should be cautious regarding their level of beta-carotene as there is a link between high levels of beta-carotene and an increased risk of poor health and ocular diseases. If you smoke consult your eyecare provider before choosing a vitamin regimen.
Nutritional supplements play an essential role in the prevention and delay of ocular and systemic conditions. If you are not sure if you are obtaining enough vitamins and minerals naturally you should consider dietary supplements. Several manufacturers have developed ocular vitamins that are rich in antioxidants specifically lutein and zeaxanthin. It is important to note that these nutrients are not a cure for AMD nor will they restore vision already lost from the disease. However they may play a key role in helping people at high risk for developing advanced AMD keep their vision. If you are interested in taking supplements to prevent ocular diseases you should consult your eyecare provider.