Have you heard that pasta, beans and apples raise your blood glucose levels less than potatoes, rice and watermelon? This advice stems from the so-called "Glycemic Index." The Glycemic Index is a meal planning method by which, its advocates believe, you can choose foods to help you control your blood glucose levels.
At present, the American Diabetes Association (ADA) experts don't feel the research on Glycemic Index warrants changes to their current nutrition recommendations, which related to carbohydrates states, it is the total carbohydrate you eat, not the type, that most influences your blood glucose levels.
What is the glycemic index?
The Glycemic Index, popularized in the early 1980's, refers to the increase in blood glucose levels that occur in the three hours after 50 grams of available carbohydrate from a carbohydrate-containing food is eaten. The Glycemic Index research shows that not all carbohydrates are created equally when it comes to their impact on blood glucose levels. For instance, potatoes raise blood glucose faster than some fruit, and beans and pasta raised blood glucose quite slowly.
Is the glycemic index useful?
Although some people, particularly in Australia, apply the Glycemic Index to meal planning, it has not been given a lot of credibility or utility by the ADA for a number of reasons. Firstly, this method looks at only one food at a time, which is not how we eat. We eat several foods at a time-starch, vegetables, meat, fruit. Secondly, it is well known that many factors beyond just the content of the food affect blood glucose levels, such as:
- Fiber content of the meal
- Ripeness of the fruits or vegetables included in the meal
- Whether the food is eaten raw or cooked and if cooked, how well cooked (i.e. al dente pasta or soft pasta)
- How quickly or slowly you eat and how quickly or slowly your digestive system works
- The time of day of the meal
Thirdly, if you only eat foods that cause a low glycemic rise, you might limit your food choices and decrease the variety of foods you eat. That's not wise. The message to "eat a variety of foods" is a central theme in the US Dietary Guidelines for Americans. These guidelines are also promoted for people with diabetes.
So what's the bottom line?
It's healthy to eat many of the low glycemic index foods because they are healthy food choices-whole grain breads and cereals, pasta, dried peas and beans, some fruits. Include these foods, but don't omit healthy foods with a high glycemic index. Remember, according to the ADA, it is the total carbohydrate you eat, not the type, that most influences your blood glucose levels.
One side point: if you monitor your blood glucose levels quite often you might find a few foods that cause your blood glucose levels to rise more or less than you expect. It's great to identify these foods for yourself. This helps you develop your "personal glycemic index." From these observations, you might decide to not eat a few foods or decide to eat just a small serving or take more diabetes medication. However, don't jump to conclusions too quickly. Try the food and observe your blood glucose levels several times before making changes.
The benefits of whole-grain food
According to a study published in the September, 2000 issue of the American Journal of Public Health, eating more whole-grain foods reduces the risk of Type 2 diabetes for women. Whole-grain products included: dark bread, whole-grain breakfast cereal, brown rice, wheat germ, bran, and other grains.
According to the study, compiled by researchers at Harvard Medical School: "Something present in whole grains may be responsible for the observed protective effect, even though the nutrient content of different whole-grain products may vary. The study also concluded that: "Other antioxidants, nutrients, or phytochemicals in whole grains or interactions among them also may play important roles in risk reduction."
