Diabetes and Eye Health

By Caroline Breton, B.Sc, Registered Dietitian

nutritionNovember is Diabetes Awareness Month, shining a spotlight on the more than nine million Canadians who live with diabetes or prediabetes. Canada has one of the world’s highest rates of diabetes and diabetes-related mortality per capita, with costs to our health-care system of almost $12 billion annually.

Diabetes is also Canada’s leading cause of blindness. If blood sugar is not well controlled, people with the condition may be at greater risk of developing glaucoma, cataracts, retinopathy, AMD, blurred vision and vision loss. Other health complications include heart disease, stroke and kidney disease. Diabetes can affect various parts of the body, including blood vessels and the eyes. With some eye diseases such as retinopathy, high levels of blood sugar weaken the walls of small blood vessels, like those in the retina, making them more prone to damage. The damaged retinal blood vessels leak blood and plasma into the retina and over time, the changes that occur as a result of diabetes lead to vision loss.

Although no specific foods or nutrients can lower the risk of developing glaucoma, cataracts or retinopathy, people with diabetes should manage their blood sugar, blood pressure and lipid profiles. When someone with diabetes has stable blood sugar levels, they are less likely to experience eye problems.

People with diabetes should get routine eye examinations from their eyecare specialist. They will also benefit from consulting a registered dietitian, who will develop an eating plan to keep blood sugar levels in check.

Learning how to manage diabetes involves lifestyle changes that require long-term commitment and personal motivation. The first step is to consult a healthcare professional to become better informed about the condition and its possible complications. The second step is to manage diabetes by following three rules: being active, eating a well-balanced diet and achieving and maintaining a healthy weight. Physical activity benefits everyone but for those with diabetes, it is especially important because it helps the body lower blood glucose levels and improves sensitivity to insulin.

Meal planning and making healthier choices can make a substantial difference in helping the body control blood sugar levels. People with diabetes need to have regular meals, follow recommended portion sizes, limit sugars and sweets, limit high-fat foods, include more high-fibre foods, make lower-fat food choices and drink plenty of water. Achieving a healthy weight is worth the effort as it will improve blood sugar levels and may significantly reduce the need for medication. By taking these steps, a person with diabetes can gain control over their blood sugar levels and keep their eyes healthy.

Nutrients for Eye Health

Since eye diseases are more common in diabetics, it is important to do everything possible to maintain eye health. Research has shown that certain nutrients are beneficial to the eyes and may reduce the risk of some eye diseases. To protect the eyes, choose foods that contain vitamin A and carotenoids, such as lutein, zeaxanthin and beta-carotene. These nutrients can be found in a wide variety of fruits and vegetables.

  • Vitamin A or beta-carotene: beta-carotene is converted to vitamin A in the body and is one of several kinds of carotenoids. Found mainly in plants, carotenoids are commonly bright yellow, orange and red pigments, which give foods their colour. Rich sources include carrots, sweet potatoes, squash, cantaloupe, peaches, broccoli and kale;
  • Lutein and zeaxanthin: these carotenoids are present in the macula segment of the retina and are believed to play a role in eye health by improving macular pigment density. The best food sources of lutein and zeaxanthin are kale, spinach, sweet potatoes, squashes, carrots, cantaloupe, corn, egg yolks and eggs enriched with lutein.

Vitamins C and E and the minerals zinc and selenium are also eye-friendly nutrients.

  • Vitamin C: mainly found in the fruits and vegetables food group, sources include citrus fruits (oranges, grapefruit and lemons), strawberries, sweet peppers, broccoli, cabbage and tomatoes;
  • Vitamin E: is a very efficient, natural antioxidant and a fat-soluble vitamin that can be stored in the liver. It is mainly found in almonds, sunflower seeds, wheat germ, vegetable oils, margarines, fish and leafy greens;
  •  Zinc: is found in a wide variety of food groups, such as meat, milk products and  grains. Sources include lean meats, oysters, fish, beans, pumpkin seeds and wheat germ.
  • Selenium: is found in nuts and seeds, fish and seafood.

All of these foods help to provide a balanced diet rich in fruits and vegetables that can promote eye health. Several eye health supplement formulations containing these nutrients are also widely available.

In order to recommend appropriate nutritional supplements and supervise their use, healthcare professionals must be aware of a patient’s medical condition, including diseases such as diabetes and hypertension, and whether a patient is a smoker or is taking medications.

For more information on diabetes or additional resources, contact the Canadian Diabetes Association at http://www.diabetes.ca. For information on food and nutrition or to find a dietitian, contact Dietitians of Canada at http://www.dietitians.ca.