The Glycemic Index

This is a term used fairly frequently but is not often understood.  Simply put, it is a measure of how much sugar gets into the blood stream for a given food.  The scale is set by pure sugar, or glucose itself which is given the value of 100.  Other foods are rated in comparison to it.  Table sugar, which is sucrose, is composed of two glucose molecules bonded together.  Therefore, on a per molecule basis it would have a glycemic index of 200.  The glycemic index should also be viewed in the context of the glycemic load.  This is the actual amount of sugar that one ingests.

Let me illustrate an example.  A typical soda contains about 39 gm of sugar and has a glycemic index approaching that of pure glucose.  Fruit also has a high glycemic index but the sugar found in fruits and vegetables is from a molecule that has one glucose molecule bonded to a galactose molecule.  Only half of the amount of glucose is delivered to the blood stream as regular sugar.  In addition, fruit has vitamins, fiber and water to go along with the ingested carbohydrate, all of which is healthy.  A typical orange has 12 gm of sugar.  It is unlikely that someone will eat three oranges at a sitting, but that is what it would take to equal the glycemic load of one soda.  It is, therefore, important to interpret the glycemic index appropriately.  I give my patients free range on the amount of fruits and vegetables they eat.  Even my diabetics.  It is hard to ingest enough fruit to cause any significant damage.

Apart from fruits and vegetables, the glycemic index can be very helpful.  Most foods are fairly obvious.  Starches can be a big source of dietary glucose.  Potatoes, bread, rice and pasta need to be watched closely.  Many breakfast cereals are quite high on the glycemic index.  As a rule, the heartier grain, the coarser the starch, the better.  Brown rice is healthier than quick, white rice.  Seven grain breads are much better than processed white bread such as Wonder Bread.  It makes sense.  The harder it is for the body to digest the food, the less sugar gets delivered to the blood stream.

Now that you know the basics, head off to a web site and start looking up foods.  There may be a few surprises for you there.  Remember to keep it simple.