Glycemic index, glycemic load and illness

First, brief definitions. There are several ways to say it, but basically, glycemic index (GI) measures the effects of carbs on blood sugar levels and is calculated by measuring glucose levels post eating carbs, whereas glycemic load (GL) is similar but takes servings into account, and is figured out by multiplying a food’s GI by the amount of carbs per serving, divided by 100.

There are many sites with GI and GL charts, one of which is: http://www.health.harvard.edu/newsweek/Glycemic_index_and_glycemic_load_for_100_foods.htm

I have never taken either seriously, and we hear more about GI than GL, but the whole thing has always been pretty controversial. I have read a lot more about GI than GL, but always preferred GL, if anything, because I hate that foods like watermelon, something that is healthy and contains more lycopene than tomatoes, is high on the GI index, and thus some people avoid it.

In my mind, there are three main thoughts about GI. 1) Diabetics follow low GI diets to control their diabetes; 2) people choose low GI foods in order to lose weight (to be sure, many have capitalized on this and there are tons of books, diets, and cookbooks based on it); and 3) bodybuilders think it is necessary to have a high GI carb source post-workout (myth).

But besides diabetes, many of us do not think about its function as it relates to overall wellness and illness. So many diseases can be controlled by diet; are GI and GL a part of that?

Barclay et al wanted to find out and performed a meta-analysis of 37 prospective observational studies in the US, Canada, Australia, and some European countries published from January 1981 through March 2007.

They found that diets with a high GI or GL independently increased the risk for type 2 diabetes, heart disease, gallbladder disease, breast cancer, and all diseases combined. The strongest effect was for type 2 diabetes, heart disease, and gallbladder disease. They also found that low GI diets were protective (as protective as diets rich in whole grains and high-fiber foods) against type 2 diabetes, coronary heart disease, and colorectal cancer.

GI seemed to have a greater positive association with the diseases than did GL, which the authors suggest may be a result of the fact that low GI diets can vary more, some being higher in (low gi) carbs and others being lower in carbs. This means that it is not the amount of carbs eaten alone but rather the GI content of those carbs that play a role.

There are so many things we can’t control when it comes to our health, and people can become ill regardless of how they live or eat, but if having a diet that consists primarily of low GI foods can be protective at all, it is, in my opinion, worth considering.

randi morse, randi.morse@gmail.com, newton, ma