GLYCEMIC INDEX, GLYCEMIC LOAD AND STARCHY STAPLES

The most common kinds of carbohydrate in foods are dietary fibres, starches and sugars. While sugars and fibre are commonly found in Nutrition Information / Nutrition Facts panels on foods and beverages, starches unfortunately aren’t – they are the truly hidden ingredient/nutrient in foods – not sugars.

Why does this matter?

When I speak with people who are following a low or lower carbohydrate diet, they typically tell me that they are avoiding breads, breakfast cereals, pasta, potatoes, rice, etc… These foods are all high starch foods. Many still eat fruit which are of course naturally high in sugars and many also consume legumes that are naturally high in starches.

Therefore, many people that think they are consuming a low/lower carbohydrate diet possibly aren’t . They are consuming a low/er starch diet, but they do not have the words to articulate it because we don’t include starch in Nutrition Information / Nutrition Facts panels in most parts of the world (other than the United Kingdom where it is voluntary). Let’s face it, it’s hard to think about something if you don’t have the right word to describe it.

What are starches?

Starches are comprised of long chains of the sugar glucose, and are found naturally in a wide range of foods from grains (wheat, rice, etc…), legumes (beans, peas and lentils), starchy vegetables (potatoes, sweet potatoes, etc…) and nuts and seeds, and they are also added to many foods as an ingredient (e.g., thickeners).

Digestion, absorption and metabolism of starches

Small proteins called amylases found in saliva and intestinal digestive juices (secreted by the pancreas) snip each bond between the glucose molecules in starches, so that by the end of the digestive process you wind up with pure glucose in the small intestine, which is then transported through the intestinal wall into the bloodstream.

Glucose circulates throughout the body and can be absorbed directly into the cells of most of the body’s tissues and organs where it usually ends up as pyruvate and adenosine triphosphate (ATP), which is our body’s main energy currency. Normally, pyruvate is also converted to ATP, producing more energy.
When glucose enters the bloodstream, our pancreas releases insulin, which signals most of the body’s organs and tissues to absorb the glucose from the blood. As we know, people with diabetes produce either essentially no insulin (type 1), or not enough insulin (type 2), and this is why their blood glucose levels can rise too high after consuming too much of a high-carbohydrate meal.

Glycemic index and glycemic load of starchy staples

In keeping with the theme of this month’s edition of GI News, we have been talking about traditional wheat pastas and comparing them to other starchy staples like bread, rice or potatoes.

Let’s take a closer look at these starchy staples GI and GLs so you can understand why we were comparing them with pastas.

As you can see, a typical serve of al dente pasta has a much lower GI and GL than most other starchy staples. It also tastes good, is versatile, is relatively cheap and has a long shelf life – important factors for most of us.

Read more:

• Barclay. Reversing Diabetes. Murdoch Books, 2015.
• www.glycemicindex.com