The glycemic index

Wednesday 23rd December 2009 3:03pm

We have all heard and read a lot about the glycemic index (GI) and the effects it might have on our diet but what is it really all about?

The glycemic index (GI) is a measure of the effect carbohydrates in food has on blood sugar levels.

Put simply this is a measure of how quickly carbohydrates break down during digestion and as a consequence release glucose into our bloodstream. The faster they break down the quicker glucose is released into the bloodstream.

In most cases the slower the release of glucose from carbohydrate in food the lower is the insulin response required by the body to move blood glucose into muscle and liver storage sites.

A low GI food will release glucose more slowly and steadily meaning more prolonged feeling of fullness and helping to stabilise blood sugar levels. High GI food causes a more rapid rise in blood glucose levels and are more suitable for energy recovery after endurance exercise or for a person experiencing hypoglycaemia. However in general lower GI foods should be eaten as a matter of course as part of a balanced daily diet.

When you are looking at the GI it is important to know what the numbers mean and it's really quite straightforward. Pure glucose is taken as having a GI of 100 and everything else is compared to this. The lower the number quoted the lower the GI ie the slower, or less available, is the glucose in the carbohydrate in that food.

Low GI 55 or less

most fruits and vegetables (except potatoes, watermelon),
grainy breads,
pasta,
legumes/pulses,
milk, yoghurt,
products extremely low in carbohydrates (some cheeses, nuts, cooking oil)

Medium GI 56–69

whole wheat products,
basmati rice,
sweet potato,
table sugar

High GI 70 and above

corn flakes,
rice bubbles,
baked potatoes,
watermelon,
croissants,
white bread,
extruded breakfast cereals,
most white rices (e.g. jasmine),
straight glucose (100)

While this is a good measure it can vary in real life for a number of reasons:

The glycemic index does not take into account other factors besides glycemic response, such as an individual's insulin response which occurs after eating.
The glycemic index is significantly altered by the type of food, its ripeness, processing, the length of storage, cooking methods, and its variety (white potatoes are a notable example, ranging from moderate to very high GI even within the same variety.
The glycemic response is different from one person to another, and even in the same person from day to day, depending on existing blood glucose levels when the food is eaten, insulin resistance, and other factors.

Furthermore as an indicator the GI may be a little limited:

The number of grams of carbohydrate impacts blood sugar levels more than the glycemic index. That is eating more of a low GI food still adds glucose to your system which manifests as a rise in blood glucose level
Lowering glycemic index leads to small improvements in the blood sugar level, but consuming fewer calories, losing weight, and carbohydrate counting would benefit the blood sugar level more.
Carbohydrate impacts glucose levels most profoundly, and two foods with the same carbohydrate content are generally comparable in their effects on blood sugar.
A food with a low glycemic index may have a high carbohydrate content or vice versa; this can be accounted for with the glycemic load.

So where does that leave us?

Consuming carbohydrates with a low glycemic index and calculating carbohydrate intake would help produce the most stable blood sugar levels.

This in turn helps determine food choices that assist to optimise our chances of being healthy through appropriate use of carbohydrates.

Herb Valley products that might assist stabilising blood sugar levels and contribute to a weight loss program:

Chromium Picolinate
Supercharged B Complex
Multi Vitamins
Kelp

This information is not intended as a substitute for qualified medical advice. Please consult a properly qualified health care practitioner.