Back July 3, 2024

Sourdough’s Secret: A Lower Glycaemic Index for better Health

Sourdough rises above the rest with its extra nutrients, lack of additives, and its tummy-friendly goodness. But did you know it also holds a secret weapon? It boasts a lower glycaemic index.

What’s the Glycaemic Index?

The glycaemic index is a scale that measures how quickly carbohydrates in a particular food raise blood sugar levels. Foods with a high GI are rapidly digested, causing quick spikes in blood sugar. Whereas, low-GI foods release glucose gradually, aiding in stable energy levels. This is important for managing diabetes and maintaining consistent energy.

The Glycaemic Index of Sourdough Bread:

Several studies suggest that sourdough has a lower GI compared to regular bread (¹,²,³) and is easier to digest (). But here’s the catch – not all sourdough is created equal. Make sure you’re getting the real deal and not some “sourfaux” impostor. Read sourdough vs. sourfaux to discover the key differences.

Furthermore, various factors influence GI, such as the type of flour used, fermentation time and the overall recipe. For example, freezing bread can also lower its GI.

According to the US Department of Agriculture (USDA) sourdough bread has a lower GI than whole wheat bread. A Low GI is a ranking of less than 55 on the glycaemic index (). As you can see in the table below, sourdough has a low GI of 54. White and whole wheat flour, on the other hand, both have a high GI of 71. Sourdough also has less sugar than both white and whole wheat and more fibre than white bread. Many non-sourdough loaves also add extra sugar into the recipe. Whereas non of our sourdough loaves have any added sugar.

SourdoughWhole wheat (non-sourdough)White (non-sourdough)
Glycemic index547171
Sugars0.5-1g 1.39g1.7g

Information from the USDA’s FoodData Central for 1 slice of bread (). Of course these are estimates, not every bread is the same.

Benefits of Sourdough Fermentation:

Sourdough bread undergoes a fermentation process where wild yeast and lactic acid bacteria break down gluten and phytic acid.

Sourdough bread’s slow fermentation process has a few positive benefits:

Gives the bread a tangy and complex flavourSeveral studies have indicated that this fermentation process gives the bread a lower glycaemic index (,,). This means it releases energy more steadily, avoiding quick blood sugar spikes.
Positive effect on textureThe lactic acid produced during fermentation makes it easier on the stomach for those with gluten sensitivities. This means that sourdough is often easier to digest than other breads. The breakdown of gluten and phytic acid during fermentation not only makes it easier to digest but also aids nutrient absorption (¹⁰).
Stays fresher for longerSourdough bread contains prebiotics, helping to keep your gut healthy (¹¹).

Final thoughts:

Sourdough bread isn’t just a delicious choice—it’s a smart move for managing blood sugar and improving overall nutrition. Want to delve deeper? Watch the video, ‘can bread by healthy?’ made by the personalized nutrition company, ZOE. And check out the importance of glycaemic index for diabetes at Diabetes UK.

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