Category Archives: Glycemic Index

RFF#113 – Acid decreases postprandial glycemia

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Or in laymen’s terms, consuming an acidic food/ingredient alongside carbohydrates will decrease the size of the resulting blood sugar spike in your bloodstream.

This is part of the reason why sourdough bread (which contains lactic acid, produced by the lactobacillus bacteria that are involved in the fermentation of sourdough bread) has a lower glycemic index, compared to regular bread.

The mechanism for how acid decreases blood sugar is uncertain. Some research has suggested that acid delays gastric emptying (the release of food from your stomach), while other studies have postulated that it may inactivate the amylase enzyme that breaks down carbohydrate.

Either way, this random food fact gives insight into the unique power that foods have when consumed in combination. So don’t hesitate to squeeze some lemon on those potatoes, it could do you some good!

I learned about this fact from:

Liljeberg HG and Björck IM. Delayed gastric emptying rate as a potential mechanism for lowered glycemia after eating sourdough bread: studies in humans and rats using test products with added organic acids or an organic salt. Am J Clin Nutr. 1996 Dec;64(6):886-93.

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RFF#51 – The Glycemic Index of a food can vary depending on the ethnicity of the person digesting it

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For anyone who isn’t familiar with the Glycemic Index (GI), it’s basically a measure of the ability of a food to raise your blood sugar. A food with a high GI causes a rapid increase in blood sugar (this is bad), while a food with a low GI increases blood sugar more gradually (this is desirable).

For years, it was assumed that the GI of a food is universal, however, research has shown that this is not the case. A study comparing the glycemic response elicited in Asians versus Caucasians, showed that the GI of a ready-to-eat breakfast cereal was 77 in Asians, while it was only 61 in Caucasians. So basically, the exact same food caused a larger spike in blood sugar in the Asians compared to the Caucasians. Researchers have speculated that this may arise from differences in starch digestion amongst ethnic groups. Nevertheless, regardless of the mechanism, it’s always interesting to see how the exact same food can affect different people in different ways.

I learned about this fact from: Venn BS, Williams SM, Mann JI. Comparison of postprandial glycaemia in Asians and Caucasians. Diabet Med 2010;27:1205-8.

RFF#31 – The glycemic index of pasta varies depending on the shape

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First, for anyone doesn’t already know, glycemic index (GI) is a measure of how quickly a food is digested and absorbed.

Ideally you want a food to be:

1) slowly digested (so it stays in your stomach longer, keeping you full for longer), and

2) slowly absorbed (so all of its energy doesn’t rush into your bloodstream which causes a hormonal imbalance [too much insulin] and increases the likelihood that the energy will be stored as fat)

Therefore, foods with a low GI (think low=slow) are better than foods with a high GI.

So, which shape is best? Well, it all has to do with the density and surface area of the pasta. Meaning thick and dense pastas, like rotini and gemelli will have a lower GI compared to pastas with a large surface area, like orzo and fettuccine.

But, in addition to the shape, the way in which the pasta was cooked will also influence the GI. More on that in tomorrow’s post…

A selection of pasta at "Campo di Fiori" in Rome

A selection of pasta at “Campo di Fiori” in Rome