Health Watch
by Peggy Biltz and Lori Hoolihan
Low Glycemic Index Diets: Separating Fact From Fiction
Glycemic index — a measure of how carbohydrate-containing foods affect blood-sugar levels — is getting much coverage in the consumer press as well as in health and nutrition journals. The popular notion is that low GI diets help with weight-loss efforts, control blood-sugar levels after meals, curb one’s appetite and prolong physical endurance. Some even report that low GI diets can stave off heart disease and prevent diabetes. Is there any truth to these claims?
The GI ranks foods, on a scale of 0 to 100, against white bread or glucose in terms of their impact on blood-sugar levels. All foods that contain carbohydrates — including bread, pasta, rice, desserts, fruits, potatoes, corn, milk and yogurt — have the potential to affect blood-sugar levels. Low GI is considered 55 or less, medium GI is 56 to 69 and high GI 70 or more. Foods with high GIs include breads, breakfast cereals, potatoes, snacks and desserts made with refined flour products. Whole grain breads, cereals, brown rice, oatmeal, most fruits and vegetables, beans and legumes are lower in GI and considered healthier choices.
Dairy generally does fairly well in discussions of GI. Ice cream, sweetened yogurts and flavored milks fall in the moderate GI range due to their added sugar. Nonfat milk, unsweetened yogurts and cheese have GIs in the low range of 0 to 30. Thus, there are a variety of dairy products that can fit nicely into the diets of consumers attempting to choose low GI foods.
Although appealingly simple to those wanting to lose weight and the growing diabetic population, there are a number of considerations when using GI to plan diets:
Most foods are consumed with other foods, not by themselves. Eating combinations of foods result in a very different GI than expected from the individual foods.
There is insufficient research showing that GI affects weight loss or controls blood sugar in the long term.
The GI of even a specific food can vary depending on its ripeness, the degree to which it is cooked and other factors. For example, a ripe banana has a higher GI than a green banana.
A person’s blood-sugar response to eating a food can vary depending on blood glucose levels, insulin resistance and prior meals and snacks consumed.
The amount of food eaten in a typical serving may be more or less than the amount used when its GI was established in a research study.
Although research on GI is intriguing and may prove useful some day, most health experts agree it is not yet realistic to use for dietary recommendations. Creating a diet based solely on GI can result in an eating plan that may exclude some nutrient-rich foods, and it may not have the desired result given the various issues mentioned above.
However, interest in low GI diets will likely continue to grow among consumers and health professionals. The industry will need to stay abreast of developments in this area — especially with increased interest in the sugar content of foods — and be ready to position dairy products appropriately to meet consumers’ needs.
Peggy Biltz is chief executive officer of the Dairy Council of California. Lori Hoolihan, Ph.D., R.D., is the council’s nutrition research specialist.