Number 9, 2008 (rev'd)
For Up-to-Date Information on Sugars in Healthy Eating
Understanding the Glycemic Index
Carbohydrates are our most important source of energy. Foods that are high in carbohydrates include grains (e.g., cereals, breads), milk products, fruits, starchy vegetables (e.g., potatoes, parsnips) and sweets. All carbohydrates are broken down by your body into sugars, such as glucose, that enter your blood stream. The glucose in your blood (or blood sugar) can be used for energy by your body, especially by your brain and muscles.
Glycemic index (GI) is a scale that ranks carbohydrate foods based on how much they increase blood glucose levels about 2-3 hours after eating. The GI uses a numbering system to label foods as low GI (less than 55), medium GI (55-70) or high GI (more than 70). Foods with a high GI are more quickly digested, and cause a larger increase in blood glucose, than foods with a low GI. Foods with a low GI are digested more slowly and do not raise blood glucose as high, or as quickly, as high GI foods.
The GI was created to help people with diabetes control their blood glucose levels. The Canadian Diabetes Association suggests that people with diabetes choose low and medium GI foods more often than high GI foods. However, it is important to note that the GI system does have some limits, including:
- The GI of a single food may change when it is eaten with other foods as part of a meal or snack
- High GI foods can also be part of a healthy diet. For example, parsnips, winter squash and rutabaga have a high GI but are also rich in fibre, vitamins and minerals
- The GI of a food may vary depending on how it is cooked or where it was grown
 The Glycemic Index (GI) is a scale that ranks carbohydrate-rich foods based on how much they increase blood glucose levels.
Sugar and Your Blood Glucose
It is often mistakenly believed that eating sugar-containing foods causes a large rise in blood glucose followed by an extreme low, causing fatigue and food cravings. The idea of a 'sugar high' followed by a 'sugar crash' is, in fact, a myth. In healthy people, the body keeps blood glucose levels within a narrow range. A gradual rise after eating, followed by a slow decline, is a normal part of the body’s regulation of blood glucose.
| Factors That Affect Glycemic Index |
Examples |
Cooking: foods that are less cooked or processed are digested more
slowly and have a lower GI than foods that are more cooked or processed |
• Less processed foods, such as slow cooking oats or brown rice, have a lower GI than foods such as instant oats or instant white rice.
• Pasta cooked “al dente” (tender yet firm) has a lower GI than pasta cooked until very tender. |
Fibre: fibre helps to slow down digestion of carbohydrate foods. High
fibre foods tend to have a lower GI than low fibre foods. |
High fibre foods such as whole grain breads, oats, beans and lentils have a lower GI than low fibre foods such as white bread, white bagels and rice cereal. |
Fat and Protein: fat or protein eaten along with carbohydrate helps to
slow down digestion and reduces the GI of the carbohydrate. |
A snack that includes carbohydrate and protein or fat has a lower GI than a snack with carbohydrate only. For example, crackers with peanut butter have a lower GI than crackers alone. |
Acids in Foods: acids in food slow down the time it takes for the stomach
to empty after eating. Acids lower the GI of carbohydrate foods. |
Vinegar, lemon juice, or citrus fruits added to foods will lower the GI of those foods. |
| Glycemic Index of Various Foods* |
| |
Low GI (<55) |
Medium GI (55-70) |
High GI (>70) |
| Grains and Starches |
• Canada’s Food Guide recommends making at least half of your grain products whole grain each day.
• All cereals provide energy, vitamins and minerals. Whole grain and bran cereals also provide fibre. |
| Cereals |
All Bran™, Steel Cut Oats, Oat Bran |
Shredded Wheat™, Quick Oats |
Rice Krispies™, Corn Flakes™, Bran Flakes™, Cheerios™, Instant Oats |
| Breads |
Stoneground Whole Wheat Bread,
12-Grain / Mixed Grain Bread,
Pumpernickel Bread |
Whole Wheat Bread,
Rye Bread,
Sourdough Bread |
White Bread,
White Bagel,
Kaiser Roll |
| Rice / Pasta |
Pasta (cooked until firm),
Converted or Parboiled Rice |
Basmati Rice, Brown Rice, Couscous |
Instant Rice |
| Fruits and Vegetables |
• High GI vegetables, such as parsnip, rutabaga and winter squash, are also rich sources of vitamins, minerals and fibre.
• Canada’s Food Guide recommends eating at least one dark green and one orange vegetable each day. |
| Starchy Vegetables |
Sweet Potato, Green Peas, Yam |
Raw Carrots, Baked Potato with Skin, New Potato, Corn |
Baked Potato without Skin, Mashed Potato, Parsnip, Rutabaga, Winter Squash |
| Fruit and Fruit Juices |
Apple, Orange, Strawberries Peach, Cherries, Grapes, Apple Juice, Orange Juice, Grapefruit Juice |
Banana, Raisins, Apricots, Grape Juice, Cranberry Cocktail |
Watermelon, Dried Dates |
| Milk Products |
•Milk products provide important minerals for bone health including calcium, phosphorus and magnesium.
• Canada’s Food Guide recommends choosing lower fat milk such as 2%, 1% or skim. |
| |
Milk, Plain Yogurt, Sweetened Yogurt, Chocolate Milk |
Sweetened Condensed Milk |
|
| Legumes |
• Legumes, including beans and lentils, are an excellent source of protein and fibre. They can be used as an alternative to meat in many dishes. |
| |
Lentils, Kidney Beans, Chick Peas, Baked Beans |
|
|
| Sweeteners |
• It is a myth that brown sugar and honey are “healthier” than white sugar (sucrose). They are all mainly carbohydrate and provide the same number of calories. |
| |
|
Table Sugar (Sucrose), Brown Sugar, Honey |
|
Remember that GI may only be one small part of healthy eating. People with diabetes should eat a well-balanced diet while paying attention to portion sizes and distribution of carbohydrate in order to manage blood glucose levels. For more information on healthy eating for diabetes, speak with your doctor or Registered Dietitian.
To find a Dietitian in your area, click on the “Find a Dietitian” link at www.dietitians.ca.
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