What is the Glycemic Index of Sourdough Bread?

When people think of sourdough bread, they’re thinking of a low-carb loaf of bread fermented and loaded with benefits – not to mention an intriguing flavor. But if you’re following a strict GI diet, you may also wonder what the glycemic index of sourdough bread is.

Sourdough bread has a glycemic index of 54, making it safe for those on low GI diets when consumed in moderation. It is a much safer choice than other types of bread, such as white bread, which has a startling 74 glycemic index.

Hello! My name’s Michelle, and my family and I love sourdough bread. Whether it’s for toast, cheesy garlic bread, or simply for a flavorful afternoon peanut butter and jelly, we consume plenty of sourdoughs. I love learning more about this crowd’s favorite bread, and I’m here to share my findings.

Read on to discover the glycemic index of sourdough bread (plus other fun facts).

What is the Glycemic Index?

Before we dive into the glycemic index of sourdough bread, I figured I should touch briefly on what the glycemic index actually is. After all, if you had mentioned this term to me a few years ago, I’d have raised an eyebrow with confusion.

The glycemic index is a value that measures how quickly a food raises blood sugar levels. It’s ranked on a scale of 0 to 100. It is essential to know these values, as high GI foods will spike blood sugar levels, which can lead to health conditions like diabetes, obesity, and heart failure.

Foods with a low glycemic index will be far safer and more beneficial to consume. Not only will they digest slowly and stabilize blood sugar levels, but they will also reduce cholesterol levels, too. A low GI diet can lead to other perks like weight loss.

Sourdough Bread Glycemic Index

Needless to say, opting for a diet consisting of low glycemic foods is highly beneficial to your health and well-being. However, it can be challenging to find bread that follows in line with a low GI diet. After all, white bread ranks at 74 – not exactly a low GI food to consume.

The good news is that sourdough has a glycemic index of 54. Considering “low” GI foods rank at 55 or fewer, sourdough is regarded as a low GI food that can be consumed while on a low GI diet. Of course, you’ll still want to consume in moderation. Overeating any kind of bread is not recommended.

Why is Sourdough Low GI?

It’s good news that sourdough bread can be consumed during a low GI diet. But why exactly is sourdough bread “safe” to consume while other types of bread are not

It’s all thanks to the lengthy fermentation process required when making sourdough bread. During this process, the yeast breaks down starches into two essential organic acids that create a low GI value:

  • Lactic acid. This first type of acid slows the absorption of starches and sugars, which would otherwise cause a sudden spike in blood sugar levels.
  • Acetic acid. The second type of acid slows gastric emptying, allowing you to digest the sourdough bread in a low-and-slow way, ensuring you fully absorb and utilize the ingredients.

Can You Eat Sourdough Bread on a Low GI Diet?

There’s nothing quite like a slice of sourdough bread. But is it truly safe for those following a strict low GI diet?

You can safely consume sourdough bread on a low GI diet. That’s because sourdough bread has a value of 54 on the glycemic index, allowing it to be a part of the “low” category. So, go ahead and have that piece of toast in the morning without worry.

Keep in mind that you do not want to overdo it, though. Consuming too much sourdough bread is still negative for your health and diet. Stick to one or two pieces per day, and your body will thank you.


Now you have tons of info about the glycemic index and what the glycemic index of sourdough bread is! If you want to learn more about this interesting topic, here are a few frequently asked questions to check out.

Is sourdough bread low glycemic?

With a ranking of 54, sourdough bread falls under the category of “low glycemic foods.” Therefore, it can safely be consumed (in moderation) while engaging in a low GI diet.

Does sourdough bread spike blood sugar?

Due to the lengthy fermentation process, sourdough bread does not suddenly spike blood sugar. It is slowly and thoroughly digested, leading to healthy blood sugar levels. You can safely consume a slice or two without fear of your blood sugar levels being affected.

Can people with diabetes eat sourdough bread?

Sourdough bread does not cause a spike in blood sugar and can also maintain healthy blood sugar levels, making it safe for most diabetics to consume – as long as it is consumed in moderation and paired with a diabetic-friendly diet.

Is sourdough healthier than regular bread?

Sourdough bread is considered one of the healthiest options for bread and much more nutritious than “regular” bread. Sourdough has more easily absorbed nutrients like lactic acid. It’s easily digested and low on the glycemic index. It also contains tummy-friendly probiotics.

Is Ezekiel bread really low glycemic?

If you want to consume bread with an even lower glycemic index, consider Ezekiel bread. This type of bread ranks at 36, making it a safer choice for those struggling with blood sugar levels (for example, those with type 2 diabetes). 

Final Words

The glycemic index of sourdough bread is just 54, compared to other types of bread with well over 70. This ranks sourdough bread as a “low GI food” that can be safely consumed with low GI diets. The low GI number comes from the lengthy fermentation.

Do you like sourdough bread? Do you follow a low GI diet? If so, what other foods do you typically eat with sourdough? Share some stuff with us!

About Michelle
I have been a lover of sweets since day one. This led me on a self-taught baking journey starting at the age of 13. It's been over 10 years since the start of my baking adventures, and I’ve learned a lot along the way. Now, people rave about my delectable treats, whether it’s a chocolate cake or a strawberry crepe.

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