Nutritional Therapy For Diabetic Retinopathy?
By A.Paul Chous, MA, OD, FAAO
Diabetic retinopathy, damage to the smallest blood vessels lining the light sensitive film at the back inside wall of the eye, is the leading cause of severe vision loss and blindness in Americans of working age. Both the landmark Diabetes Complications and Control Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated that tighter control of blood sugar significantly reduces the chances of developing or worsening diabetic retinopathy in patients with type 1 and type 2 diabetes, respectively. The UKPDS also demonstrated that tighter control of any high blood pressure greatly reduces the risk of vision loss in patients with type 2 diabetes. Even with tighter control of blood glucose and blood pressure, however, many patients still lose vision to diabetic retinopathy.
Although laser treatment of severe diabetic retinopathy has been proven to greatly lower the risk of severe vision loss, much attention is now focused on preventing and minimizing this common diabetes complication with drugs that are used to treat other medical conditions, including blood pressure medicines like the so-called angiotensin receptor blockers (ARBs), statin drugs that lower cholesterol (e.g. Lipitor), diabetes drugs like rosiglitazone (Avandia) and various nutritional supplements (e.g., benfotiamine, curcumin and pine bark extract). It is interesting to note, however, that relatively little attention with respect to diabetic eye disease has been paid to the one substance every single person with diabetes ingests — food. In my view, this is a major mistake because day to day dietary choices may dramatically impact our health, including the health of our eyes.
A recent paper appearing in the American Journal of Clinical Nutrition, for instance, showed that non-diabetic patients with age-related macular degeneration (the leading cause of severe vision loss in the U.S.) were much more likely to have severe vision loss if they consumed diets having a high overall glycemic index, that is, diets containing higher amounts of refined carbohydrates that are converted rapidly by the body into glucose. Although use of the glycemic index in diabetes care is somewhat controversial for a number of valid reasons, it is interesting to note that high glycemic-index foods like potatoes, white bread, and rice are known to simultaneously raise blood glucose levels and levels of inflammation in body tissues — and that presence of inflammatory proteins within the retina is one of the first and most consistent features of both diabetic retinopathy and macular degeneration.
Perhaps more to the point is a post hoc nutritional analysis of DCCT patients showing that the rate at which diabetic retinopathy worsens was directly correlated with total calories consumed, the total amount of fat consumed (especially saturated fats and monounsaturated fats), lower intake of dietary fiber, and cigarette smoking. The positive correlation of saturated and monounsaturated fat, and the negative association of dietary fiber with retinopathy progression and other well established retinopathy risk factors (like high blood pressure and glycosylated hemoglobin) in this study suggest but do not prove that animal-based food products promote retinopathy much more than plant-based products. Animal products are high in saturated and monounsaturated fat, and have no dietary fiber.
So what should we eat to avoid vision loss from diabetes? My recommendation is to eat an anti-inflammatory diet that emphasizes low glycemic-index vegetables, nuts and whole grains, with a minimum of 25 grams of dietary fiber daily. There is much evidence that this so-called ‘Mediterranean Diet’ aids in weight loss and maintenance, prevents atherosclerosis and heart disease, and helps stabilize blood glucose levels – so it is very well-suited for patients with diabetes. Avoiding foods containing refined carbohydrate, high amounts of (especially animal) fat, and limiting total calories consumed will not only reduce the risk of severe retinopathy, but other small and large blood vessel complications of diabetes. Finally, please remember to do whatever it takes to stop smoking cigarettes and talk with your eye care specialist about dietary choices that promote healthy eyes and good vision.
For more information on diabetic eye disease, consult Dr. Chous’ book Diabetic Eye Disease: Lessons From a Diabetic Eye Doctor, Fairwood Press, Seattle, 2003.
Read more about Dr. Chous here.
Visit Dr. Chous' website here.
NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.
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