September 16, 2012 by Johanna Burani
You may have heard or read about the glycemic index (GI) before, but do you really know what it is? what it measures? what it means?
Canadian scientists invented the glycemic index in the early 1980s to measure how quickly carbohydrate-rich foods are digested in the gut. In other words, the GI measures how long it takes a carb to become glucose and drop into the bloodstream. The researchers tested real foods on real people – no mice or test tubes, just normal people – and they came up with real numbers.
Think of any carb: a slice of bread or pizza, an Oreo cookie, a peach. Each of these foods has certain properties that will always belong to them. A peach, for example, will always be round, “peachy” in color, juicy and fibrous. And, because it’s been tested, we know it has a GI value of 28 (low). Its GI value helps to describe the peach as much as its other characteristics.
The actual glycemic index starts at zero and goes to 100 and is divided into three sections: LOW (0-55), MODERATE (56-69) and HIGH (70+). A peach has a low GI value (28) and that means it is slowly released as glucose from the gut into the blood.
There are labs in Canada, Australia, Europe and other places that follow the same strict World Health Organization-approved protocol for GI testing. To date their studies have deciphered the GI values of more than 2000 foods. These values were most recently published in 2008 as The International Tables of GI and GL Values. GI values also may be found at www.glycemicindex.com or www.gilabs.com.
- What is the glycemic index? A numerical chart of carbohydrates.
- What does it measure? How quickly carbs are digested in the gut and released as glucose into the blood.
- What does it mean? The GI tells us if a carb, once digested, enters the blood quickly or slowly. This information can have a profound impact on health concerns such as diabetes, heart disease and weight management.