Glycemic Index: New Way to Count Carbs?
Evidence Mounts for Low-Glycemic Index Diet to Control Diabetes
What's High, What's Low?
Although important, the numbers can also be confusing because the glycemic index of some foods may surprise you. As a general rule, the same low-fat, high-fiber fare -- fruits, vegetables, and whole grains and legumes -- often advised to manage weight and help prevent diabetes and other health conditions, have a low glycemic index. Conversely, starchy and processed foods such as potatoes, breads, and cereals usually have a high glycemic index.
But there are exceptions. For instance, a bowl of All-Bran cereal has a glycemic index of 54, while a serving of spaghetti rates at 41, meaning the high-fiber cereal spikes blood glucose more quickly and drastically. A handful of raisins is 64, more than a serving of popcorn, at 55. White rice (56) has nearly twice the glycemic index of a glass of apple juice, and an orange (43) has almost half the index of watermelon (72).
The American Journal of Clinical Nutrition lists any food under 55 as a low-glycemic food and any food more than 70 as high glycemic.
Haagen-Dazs vs. Baked Potato
"I remember one study that compared various foods found that a bowl of Haagen-Dazs ice cream raises blood glucose at a slower rate than a baked potato," Bernstein tells WebMD.
Still, the use of diets with low glycemic index in the treatment of diabetes remains controversial. There are contrasting recommendations around the world, the Australian researchers note in their study. It appears in this month's issue of Diabetes Care.
One possible reason: Most of the studies thus far measuring blood sugar response to glycemic indexed foods have been encouraging but small, says Angela D. Liese, PhD, MPH. Liese recently completed her own research on how foods with high glycemic indexes affect "metabolic syndrome" -- a cluster of conditions that includes obesity, high blood cholesterol, high blood pressure, insulin resistance, and diabetes. Her results have not yet been published.
The australian researchers' analysis of 14 studies had a total of only 356 patients.
Time for a Change?
"This study is important because it shows some really encouraging data, but a lot more research is needed," says Liese, an epidemiologist at the University of South Carolina. "If you want to get to the point of reaching new dietary recommendations, much, much larger studies are needed."