The Glycemic Index & Blood Sugar Benefits of Sourdough

May 6, 2024

Written by Whitney Stuart, MS, RDN, CDCES. This article will explore why sourdough bread can be considered a gut-friendly food for blood sugar balance.

Post pandemic, it felt like everywhere you looked people were making their own bread. Banana bread, sandwich bread, you name it. Now, in 2024, sourdough starters seem to be popping up all over social media. Many of my patients come to me wondering if sourdough is considered a gluten-free bread. Or, if they should be eating more sourdough bread, because it’s healthy?

As a Registered Dietitian and an individual with celiac, it felt like a good time to discuss the difference between sourdough bread and gluten-free bread.

Sourdough vs. Regular Bread: A Nutritional Showdown

Which is Better for Digestive Health?

Unlike conventional bread-making methods, sourdough fermentation involves wild yeast and lactic acid bacteria. This dynamic duo break down carbohydrates, gluten, and phytic acid, rendering the final product more digestible and nutrient-rich.

The Glycemic Index of Sourdough

Thanks to the magic of fermentation, sourdough bread boasts a lower glycemic index of 54, compared to its non-fermented counterparts. Glycemic index measures how food affects blood sugar. Sourdough has a lower impact because of the fermentation process. Releasing carbs slowly helps keep sugar levels steady, providing lasting energy and feeling full throughout the day.

Is Sourdough Easier To Digest For Those With Gluten Sensitivities?

Sourdough bread, by its original recipe, is not gluten-free but many individuals with sensitivities say they tolerate it better. Fermentation is required to make any type of sourdough bread starter, including the wheat (or whichever flour is being utilized!).

This process makes the gluten easier to digest when consumed after baking! But, sourdough can be gluten-free if made with gluten-free ingredients like millet and arrowroot flour.

Why Sourdough Is Better For Blood Sugar Regulation

The process of sourdough fermentation is better for blood sugar levels than regular bread. Fermentation involves the breakdown of carbohydrates in bread dough by natural yeasts and bacteria; a process that can help regulate blood sugar levels by slowing down the absorption of sugars into the bloodstream. Maintaining good metabolic health is crucial for overall well-being and can be supported by incorporating sourdough bread into your diet.

Blood Sugar Benefits of Sourdough Bread

Lower Glycemic Index (GI): Sourdough has a glycemic index of 54, which is much lower compared to regular bread. Foods with a low GI raise blood sugar levels more gradually, promoting stable energy throughout the day.
Fermentation: During fermentation, sourdough’s active microbes break down phytates, enhancing nutrient availability and easing digestion. This process contributes to its blood sugar-friendly profile.
The Phenolic Connection: Sourdough contains phenolic compounds, antioxidants, and gamma-aminobutyric acid (GABA). These may contribute to its anti-diabetic properties.

Dietician-Recommended Ways To Reduce High Blood Sugar Levels With Sourdough

Even though sourdough bread is technically less glycemic, consider these recommendations to really optimize your blood sugar! As a dietitian and diabetes educator I focus on creating blood sugar bliss (all day smooth energy without dips!) by avoiding lonely carbs.

To regulate blood sugar, pair that gluten-free sourdough bread with protein-rich toppings like hemp seeds and nut butter or avocado and smoked salmon. Pairing carbohydrate foods with protein and fat is your key to better energy and improved blood sugar. Experiment with flavor using wholesome spreads, such as hummus or Greek yogurt, for a nutrient-packed gut-friendly meal!

Gluten-Free Sourdough: Is It as Beneficial as Gluten-Containing Sourdough?

Potential Reduction of Anti-Nutrients in Gluten-Free Grains

Some gluten-free grains contain anti-nutrients, such as phytic acid, which can inhibit the absorption of minerals like iron, zinc, and calcium. The fermentation process in sourdough bread may help break down these anti-nutrients, increasing the bioavailability of minerals and improving overall nutrient absorption. A balanced microbiome improves digestion, enhances immune function, and reduces inflammation.

Because gluten-free sourdough bread undergoes a natural fermentation process, it enhances digestibility. This can reduce the likelihood of digestive discomfort and support gut health.

A Lower Glycemic Index Remains in Gluten-Free Sourdough

Because sourdough fermentation alters the structure of carbohydrates in bread, it results in a lower glycemic index compared to conventional bread. Gluten-free sourdough bread may lead to a slower rise in blood sugar and overall more stability after consumption, reducing the risk of spikes and crashes in energy.

Avoiding Gluten? Don't Avoid Carbs All Together

Instead of the popular idea of cutting out carbs and grains completely (an easy assumption when you have a celiac diagnosis!), it's actually better to focus on adding nutrients to your diet. This can lead to a diverse population of healthy gut bacteria and overall well-being.

One way to increase good gut bacteria is to eat more fermented foods like sourdough. Fermented foods can improve blood sugar and help our health by adding good bacteria to our gut. Sourdough fermentation promotes the growth of beneficial bacteria, which can contribute to a healthy gut microbiome.

How Fermented Foods Can Help Regulate Blood Sugar

Fermented foods (FFs) are culinary wonders resulting from the microbial transformation of raw ingredients. These foods have been part of human diets for centuries, offering both flavor and health benefits.

The Microbiome Connection:

Fermented foods, such as yogurt, kimchi, sauerkraut, and kombucha, contain living colonies of beneficial microorganisms. These can potentially enhance our own microbiome.
Gut microbiome diversity may decrease your risk for diabetes. Research shows that pre-diabetic and type 2 diabetes patients had less gut variety and diversity than people with normal glucose tolerance.
A healthy gut plays a crucial role in blood sugar regulation. Research indicates that a balanced gut microbiome positively influences insulin sensitivity, glucose metabolism, and overall metabolic health. Key factors include fiber-rich diets, probiotics, and prebiotics. By nurturing your gut health, you can enhance blood sugar control and reduce the risk of conditions like diabetes. Prioritizing gut-friendly foods and lifestyle choices is essential for maintaining optimal blood sugar levels.

The Scientific Evidence

The scientific evidence linking FFs to diabetes management is still evolving. Some key points:

Stanford Study (2021): A study published in Cell revealed that FFs increase microbiome diversity and reduce inflammatory proteins—both relevant to diabetes risk.
Brazilian Review (2020): Researchers highlighted that traditional fermented foods may aid in glycemic control, weight maintenance, and antioxidant capacity.
Nutrients Review (2018): FFs were found to enhance antioxidant capacity and reduce diabetic-associated complications.
Phenolic compounds, antioxidants, and gamma-aminobutyric acid (GABA) in FFs may contribute to their anti-diabetic effects.

Other Benefits of Sourdough and Fermented Foods

Do you eat fermented foods on a regular basis? As a dietitian, I regularly promote the inclusion of fermented foods in my patient’s diet for many reasons. Fermented foods can offer several benefits, primarily due to their impact on gut health and the way they affect digestion and nutrient absorption.

Improved Gut Health: Research suggests that a healthy gut microbiome can help regulate blood sugar levels by improving insulin sensitivity and reducing inflammation.
Increased Nutrient Absorption: Fermentation can enhance the bioavailability of nutrients in foods, including vitamins and minerals important for blood sugar regulation.
Regulation of Appetite: Fermented foods may help regulate appetite and promote satiety, which can indirectly support blood sugar management.
Reduced Inflammation: Probiotics and other bioactive compounds found in fermented foods have been shown to have anti-inflammatory effects, which may help improve insulin sensitivity and glucose metabolism.

Dietician-Recommended Ways To Reduce High Blood Sugar Levels With Sourdough

Introducing Sourdough Bread for Gluten-Free Gut Health

I received a diagnosis of celiac disease in 2009. This diagnosis was tough, but it made me realize my gut health was in a bad place. I became even more interested in studying gut health after my diagnosis. I learned that having a variety of foods is better for your digestive system than cutting out certain foods. This diversity helps create a healthy microbiome in your gut.

But back to gluten! Celiac disease, an immune reaction to gluten, affects 1% of the population. Meanwhile, gluten intolerance is more common at 13% of the population. Most people with celiac disease find it easier to avoid bread, as unfortunately, for many years, gluten-free bread has been equal to sawdust.

My Favorite Gluten-Free Sourdough

Now, almost 15 years after my diagnosis, I’ve found gluten-free options that taste good and make me feel good. One of those being gluten-free sourdough bread from Bread SRSLY. Gluten-free sourdough is a good choice for those with gluten intolerance, wanting to improve their blood sugar and gut health. It's both enjoyable and beneficial - hurrah!

Let's explore fermented foods and their benefits for gut health and blood sugar. We'll also discuss the innovation of gluten-free sourdough bread and why it's better than its traditional gluten-free counterparts. This blog post will explain sourdough fermentation, its benefits for blood sugar management, and its importance for metabolic health.

As a registered dietitian, I'm passionate about blood sugar regulation as a way to improve longevity, prevent metabolic disease and improve metabolism. And, if you didn’t know already, health really starts in the gut. So, next time you’re craving avocado toast, consider a slice of gluten-free sourdough bread that will satisfy your needs and support your gut.

Whitney Stuart is a Certified Diabetes Educator and Registered Dietitian focused on simple and sustainable health solutions using blood sugar balance and food as medicine. Whitney has celiac and enjoys spending time making loaded avocado and egg toast on Bread SRSLY with her husband and 1 year old!