January 14, 2013

Points to Consider About Food

The glycemic index (GI) and the glycemic load (GL) are two of the more meaningful terms in understanding the value of food and how each affects our blood glucose levels. This is a topic everyone with diabetes needs to be aware of and learn the general principles.

Everyone also needs to be aware that to some this is a religion, and therefore they can endanger their health. I will warn that this topic and the principles behind this should be used as a guide, but not as a bible. First, the glycemic values were determined using healthy people and not patients that were obese or that had any diseases. Therefore, we cannot be positive that the tables are exactly right for us. We do need a starting point, so I accept the tables as a starting point.

I will direct your reading to several people that have influenced my thinking about the glycemic index and glycemic load. The first was this book - The New Glucose Revolution, New York, Marlow & Company, 349 pages, by Dr. Jenny Brand-Miller, et al. I currently have the third edition.

Computing the glycemic load is fairly easy and will help in determining whether you are safe in eating the particular food, or will have high blood glucose levels briefly or for a longer period. Using the example from a blog by Dr. William Davis, we have the following: (quoting) “GL = (GI x amount of carbohydrate) / 100.
GL is therefore the GI that incorporates the glycemic potential of the food of interest. GI does not vary with portion size; GL varies with portion size.

Let’s take whole-wheat pasta, a food regarded by most people as a healthy choice. Whole-wheat pasta has a GI of 55–fairly low–and a GL of 29. A serving of 180 g (approximately 6 oz cooked) provides 50 g carbohydrates.” So using the formula above the GI of 55 X 50 g carbohydrates = 2750 divided by 100 = 27.5 for GL – not the 29 that Dr. Davis has. In either case when you look at the graph from David Mendosa's web site, you will see that the GI of 55 is the top end of the low range and the GL is well into the high range. This means that the whole-wheat pasta will raise blood glucose for a long period. This will depend on your body chemistry so actual time is difficult to measure. This is a good reason to avoid whole-wheat pasta.

Doctor Davis also has another blog on the glycemic index. By entering “glycemic index” in the search box on David's site, it will return many more articles by David and many that you may wish to read. Here and here are two of the articles.

If you have more interest in blogs on glycemic index go to this site and subscribe for a monthly newsletter.


David Mendosa said...

Good article, Bob! When I first learned I had diabetes back in 1994, I got very interested in the glycemic index. I still think it's great, but like you say, it doesn't explain everything. I now know that it's major limitation is fructose. This sugar has a quite low GI, but for other reasons, which I am sure that you will be discussing, is dangerous for us.



Bob Fenton said...

Thank you, David! I had totally passed on that point. The book only has one paragraph on fructose and lists the GI as a "modest 19". The other statement of value is that it goes directly to our liver and therefore into our blood sooner than glucose.

I will have a blog about fructose being a direct link to diabetes in a future blog and possibly another one.

Fructose is the scourge of our problems with diabetes.