Tuesday, September 17, 2013

(In the last post, I shared what I had learned about diabetes, glucose, and started talking about the glycemic index.)  

Finding a food’s glycemic index is an involved scientific process. It was decided that since it is known that sugar will increase blood sugar quickly and then it will drop quickly that sugar would be assigned a ranking of 100 on the glycemic index and that all other foods would be measured against sugar. To test a food’s glycemic index, 10 or more test subjects are given 50 grams of a carbohydrate. Scientists then test the blood sugar of the test subjects at intervals over a two hour period. After that information is recorded, the scientists then test the same test subjects after giving them 50 grams of sugar. The difference between the tests indicates the carbohydrate’s glycemic index ranking. 

This is a long and involved process. There are still many foods that have not been tested. Also it has been determined that when you combine ingredients, the glycemic index can be affected. So, while the glycemic index is very scientific, there is still much that needs to be learned.
High glycemic index foods are not bad nor are low glycemic index foods good. The glycemic index information has to be balanced with other information. For example, peanut M&Ms have a low glycemic index. You would need to consider the amount of fat that you were consuming when you ate the candy. Let’s compare the peanut M&Ms with a baked potato without the skin. The potato has a high glycemic index but it has other nutrients that are good for you. You cannot just depend on the glycemic index of a food to decide whether or not you should eat it. 

Also, it was determined that the glycemic index portions were not the same as the portions that people would normally eat.  There are times that the amount of a food tested would give it a high glycemic index but you could eat a smaller quantity and the effect would be much different.  It was because of this that the glycemic load was introduced. 

For example, if you were to look at the glycemic index for carrots, they have a ranking of 68 which would put them in the medium category on the glycemic index. In the testing process, scientists feed the subjects enough of each food to provide 50 grams of carbohydrate available for absorption into the bloodstream. Because carrots contain unavailable carbohydrates and a lot of water, the portion size tested for carrots is seven (7) full size carrots.   

The glycemic load takes into account the glycemic index and the amount of the food that you are actually going to consume. To determine the glycemic load, you have to do a little math. The calculation is as follows:

(Glycemic index X Grams of carbohydrates) / 100*

Going back to the carrot example, when you look at one 8 inch carrot, the glycemic load is 11. Compare that to 2/3 of a cup of instant white rice which has a glycemic load of 26. When you change from using just the glycemic index to using the glycemic load, the values for food items come more into line with what you might expect. The highest glycemic load items are potatoes, rice, and bread.  Vegetables and fruit are at the lower end of the scale. 

In summary, the glycemic index and the glycemic load are tools that can be used to help control a person’s blood sugar level. The goal is to avoid highs and lows in one’s blood sugar levels. By utilizing the glycemic load information, a person can eat various foods that will spread out the effects from those foods. 

Thanks for reading!

*For those of you who have been away from algebra for a while, you do the calculation inside the brackets  first and then you divide by 100.  

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