Nutrition and Vitamins
As optometrists, we believe strongly in preventative care. This is because many eye diseases are preventable, and some eye diseases have no cure. Our doctors can provide you with information on what you can do to reduce the risk of developing preventable eye disease. Lifestyle and nutrition factors play a huge role in your likelihood of developing diseases such as diabetes, hypertension, cataracts, AMD, Dry Eye and more. If we do not suffer from eye disease ourselves, most of us know someone, or are related to someone who has been affected by sight-threatening eye disease. The most prevalent disease for which preventative counselling is important is AMD or Age-related Macular Degeneration.
Unfortunately, to study the effect of nutrition and lifestyle on disease, we must look at very long-term studies that take years to complete and are based on speculation of what may and may not be of benefit. AMD is a debilitating disease of the central retina for which there is no cure. There are a variety of risk factors for the disease, some of which are genetic, and some of which are modifiable. Most of our current knowledge comes from the AREDS studies. This has been combined with current knowledge and schools of thought on the benefit of certain protective pigments and anti-inflammatory mediators.
From the AREDS study, it is clear that there is some benefit derived from anti-oxidant vitamins A, C, E and Zinc in the prevention of AMD. The study did show a reduction in the advancement of moderate disease to severe disease in 25% of cases. Unfortunately, the results of the AREDS study were not applicable to those at risk, or those with mild disease.
Furthermore, new data on genetics shows that some patients may even do worse with high doses of supplemental zinc. The debate and studies in this area are still in their infancy, but it is prudent in the interim to avoid high doses of zinc. There is recent data showing that the carotenoids lutein, zeaxanthin and meso-zeaxanthin are very important in macular health in the early stages of AMD, and are safe to take regardless of genetic profile.
Although the Harvard study showed a reduction in AMD progression in those who consumed dietary omega 3 (fish), the jury is still out on the value of omega 3 in supplement form. The big question, the answer to which will likely still be many years away, is how much of these supplements to take for a beneficial effect? We always recommend to eat a healthy diet, high in micronutrients, and then supplement as needed if the disease is progressing.
Too much supplementation can be harmful. For instance too much vitamin A can be toxic to the liver, too much vitamin E can interfere with blood thinners, and zinc interferes with absorption of many medications and has been associated with Alzheimers and prostate cancer. The ideal source of vitamins and minerals is of course obtained through proper nutrition, and here are your best sources:
Lutein/Xeaxanthin – green, leafy vegetables; yellow, orange and red fruits and vegetables; eggs; poultry
Omega 3 – cold water fatty fish (salmon/trout) at least twice weekly
Vitamin A – milk, eggs, liver, fortified cereals, darkly colored orange or green vegetables (such as carrots, sweet potatoes, pumpkin, and kale), and orange fruits such as cantaloupe, apricots, peaches, papayas, and mangos.
Vitamin C – red berries, kiwi, red and green bell peppers, tomatoes, broccoli, spinach, and juices made from guava, grapefruit, and orange.
Vitamin E – vegetable oils, nuts, green leafy vegetables, avocados, olives, wheat germ, and whole grains
Zinc – oysters, liver, beef, lamb, crab, wheat germ, sesame and pumpkin seeds, dark chocolate, peanuts
There are many easy things you can do to increase your intake of these healthy nutrients. If you would like a place to start, we recommend a book called \”EyeFoods\” which can be purchased online, or at our office. There are great recipes here.
Since there is no consensus on the proper dosage of supplements, a combination of good diet and supplementation is your best defense. You will likely be given a questionnaire by your optometrist that takes into account your current intake of nutrients. Your general health, other medications/supplements, age, and risk or presence of AMD will determine the recommendation given. It is important that this advice be discussed with your family physician before embarking on any long term supplementation. It is also important to control other modifiable risk factors including cessation of smoking and exposure to second hand smoke (smoking increases your risk by 6 times!). UV exposure can also increase your risk of AMD, especially if you are young.
In addition to prevention of AMD, most of the above also applies to the prevention of early cataract formation. Omega-3 supplementation (especially in the triglyceride as opposed to ethyl ester form) also greatly aids in the treatment of Dry Eye disease. Our optometrists can discuss this in more detail at your visit.