Glycemic Index

Does the type of carbohydrate really matter? Why is there so much controversy about the use of Glycemic Index in the dietary management of diabetes type 1/type2.
Janine Freeman, RD, CDE, in her Guest Editorial of the Diabetes Forecast September 2005 ( www.diabetes.org ) ,said that the glycemic index will soon be the fad that will replace the low-carbohydrate diet fad.

The glycemic index (GI) ranks carbohydrate foods based on how they affect the body's blood glucose levels. "High GI" foods such as white rice , corn, potato, bread; fruits like ripe banana, watermelon, cantaloupe, pineapple, and low-fiber cereals greatly impact blood glucose levels. "Low GI" foods such as whole grain breads, bran cereals, oats ; most fresh fruits and vegetables; dried beans,peas, legumes, seeds and nuts ; rootcrops, milk, yoghurt, and sugar alcohols produce less of an effect. Recently, some weight loss diets have popularized the concept of the glycemic index, linking low GI foods to weight loss and high GI foods to weight gain.
The usefulness of the glycemic index in the treatment of diabetes has been controversial since its creation some 25 years ago. It's easy to understand why. The idea of classifying foods into groups—those that greatly affect blood glucose and those that do not—sounds very appealing to people with diabetes. It seems like it could make meal planning easier and improve after-meal blood glucose levels.
Unfortunately, it's not that simple. Here are a few reasons , according to Freeman :

1. The GI of a food varies substantially depending on the kind of food, its ripeness, the length of time it was stored, how it was cooked, its variety (potatoes from Australia, for example, have a much higher GI than potatoes from the United States), and how it was processed.

2. The GI of a food varies from person to person and even in a single individual from day to day, depending on blood glucose levels, insulin resistance, and other factors.

3. The GI of a food might be one value when it is eaten alone and another when it is eaten with other foods as part of a complete meal.

4. The GI value is based on a portion that contains 50 grams of carbohydrate, which is rarely the amount typically eaten.

5. Most GI values reflect the blood glucose response to food for only 2 hours, whereas glucose levels after eating some foods remain elevated for up to 4 hours or longer in people with diabetes.

In addition, the American Dietetic Association ( ADA) reports that research has found that blood glucose levels peak at about the same time regardless of the carbohydrate source. Also, the body’s insulin response to a specific food is not directly related to the carbohydrate content of the food or the GI value.

Furthermore, figuring out which foods are "high GI" and "low GI" can be complicated, too, because it depends on which base reference is used to determine the GI—white bread or glucose. What is interesting is that many high-fat foods, such as candy bars and pizza, have a low GI. If food manufacturers begin lowering the GI of processed foods by adding high-fat ingredients or high-fructose corn syrup (which has a low GI), the same dilemma as when low-carb products began inundating the market will occur . Junk foods will be altered and labeled as healthy !

Some studies show small improvements in A1Cs among people who are attentive to the glycemic index. But reducing calories, weight loss, and basic carbohydrate counting have been shown to be more effective in improving A1Cs among people with type 2 diabetes than basing diet decisions on the GI.

Freeman does not suggest eliminating "high GI" foods in favor of "low GI" foods to gain better blood glucose levels for two reasons. First, there is not enough evidence yet to show that such an action actually will improve your blood glucose levels; and second, choosing foods based solely on GI will compromise healthy eating.

Freeman suggests basing food choices on a nutritionally balanced diet, while controlling total carbohydrates, as a first measure. Then, if after-meal blood glucose is much higher after eating certain foods, one can either choose to eat smaller portions of those foods or adjust mealtime diabetes medication.

ADA Bottom Line: At this time, research does not support the claim that a low GI diet causes significant weight loss or helps control appetite. For people with diabetes, monitoring total grams of carbohydrate remains the key strategy. However, some individuals with diabetes may be able to use the GI concept, along with blood glucose monitoring, to “fine-tune” their food choices to produce a modest improvement in postmeal blood glucose level.

www.eatright.org

The British Dietetic Association, on the other hand, recommends low GI pasta for
carbohydrate loading before a sports event and high GI foods like sweet pastries
and drink for fast release of carbohydrate, quickly replacing glucose in the
bloodstream after an event. GI is not supposed to be used in isolation.

www.bda.uk.com