The glycemic index is another tool in determining which foods have the most benefit if you're diabetic or have insulin resistance. The glycemic index was created to give more insight into which types of carbohydrates raise your blood sugar more than others. The assumption that simple sugars would raise blood sugars more than starches and other complex carbohydrates doesn't always hold true, the Linus Pauling Institute at Oregon State University reports. Both diabetics and people who have problems with hypoglycemia or insulin resistance can benefit from determining which foods have the lowest glycemic index.
Definition
Foods are ranked as having a high or low glycemic index, with each food assigned a number from 1 to 100, with low numbers indicating low glycemic index foods. Low glycemic index foods raise blood sugar levels more slowly after eating. Because a sharp rise in blood sugar levels leads to an outpouring of insulin to deal with the glucose, foods with a high glycemic index can cause hypoglycemia, an abnormal drop in blood sugar levels that occurs a few hours after eating. Foods with a low glycemic index digest more slowly and keep blood sugars more stable, without sudden rises and drops.
Determination
To determine the glycemic index of a food, volunteers eat a food containing 50 g of carbohydrates on one day and either pure glucose or white bread as a control on another day, the Linus Pauling Institute explains. On both days, blood sugars drawn before eating and for several hours after are compared to one another to determine the glycemic index of the food. A food that raises blood sugar more slowly yields a blood sugar curve that falls below that of the control. The percentage difference becomes the glycemic index of the test food. A food that yields blood sugar levels 75 percent as high as those obtained after eating pure glucose has a glycemic index of 75.
Factors
A number of factors determine a food's glycemic index. Some simple sugars, like fruits, contain large amounts of fiber, which slows their digestion and absorption into the bloodstream, lowering their glycemic index. Riper fruits, which contain more sugars, digest more quickly. Foods with a higher fat and acid content also absorb more slowly and lower the glycemic index. Some starches digest much more quickly than others; potato starch digests faster than barley, for example.
Benefits
The benefits of knowing a food's glycemic index include better control of blood sugars; better control of appetite, since foods with a lower glycemic index help you feel full longer; and a possible reduction in diabetes medication, if blood sugar levels remain more stable.
Disadvantages
Foods with a low glycemic index don't always supply the best nutrition. Some candy bars have a lower glycemic index than brown rice, The Merck Manuals Online Medical Library says, but they supply little in the way of nutrition. The glycemic index also doesn't take into account that different ways of preparing food may also affect the glycemic index.
