Is Sourdough Bread Healthy?

Bread products are a staple of the Standard American Diet and in recent years have become one of the most controversial nutrition topics as well.  But not all bread products are created equal.  I was recently asked a question specifically "is sourdough bread healthy?" and thought it would be a fun topic to post on. The more I researched the mechanisms at play in sourdough bread, the more fascinated I became!

What is Sourdough Bread & What Makes it Unique?

Almost all breads use a process of "leavening" that give them the airy, light & fluffy texture.  Most modern breads use a quick acting yeast that "rise" within a 30 minutes to a few hours. This type of bread making really only began around the industrial revolution and became more prevalent in the last 100 years.  Sourdough bread uses a slower fermentation process that leavens the bread and takes 12-24 hours to rise. This was the original/traditional way to make bread dating back to ancient egypt around 1400 BCE. 

The secret is in the bacteria and time.  Similar to a SCOBY in Kombucha the "Mother or Starter" of sourdough is a culture of beneficial bacteria (saccharomyces cerevisiae) that feed off of naturally occurring yeast in the flour, air & water.  There is a symbiotic relationship between the yeast and bacteria. The yeast and bacteria feed off of the starch in the flour (specifically the fructans) and creates CO2 as a byproduct, which leavens the bread. Another beneficial byproduct of this fermentation process are organic acids, which give sourdough bread its characteristic flavor (lactic acid & acedic acid).

SO, fermentation and the time it takes to leaven are keys to what makes the traditional sourdough a healthier alternative.  Let's look at what these benefits are.

Gut Health

Many people that have digestive discomfort when eating modern bread notice that sourdough bread does not give them the same discomfort. There are 2 main reasons for this:

1) Gluten: Even though sourdough IS NOT gluten free, it does have significantly less gluten than modern breads. During the long fermentation process some of the proteins of the flour are also getting broken down. Wheat Gluten is composed of primarily 2 proteins: glutenins & gliadins. What causes digestive discomfort and gluten sensitivity is the inability to properly digest these proteins in gluten. During this long fermentation process enzymes are also created which "pre-digest" these proteins & help us more easily digest these proteins & lessen the chance of discomfort.

*Gluten Sensitivity & Intolerance is a complex & controversial topic of nutrition, but not the focus of this post. I will just say that Gluten Sensitivity is a growing issue and there are many factors including modern wheat & bread baking as I mention above, but the health of your digestive tract & intestinal permeability is also a MAJOR player. This will be addressed in future posts, so stay tuned!

2) Fructans & FODMAP Sensitivty:  FODMAP sensitivity is also a major topic that will be discussed in future posts, but many people are sensitive to high FODMAP foods. Fructans are a type of Oligosaccharide that is found in Wheat (the "O" in FODMAP).  During the long fermentation process of sourdough these fructans are also broken down by the yeast and bacteria, which helps make them a lower FODMAP food than modern breads.

3) Fiber & Prebiotics: Now most fermented foods are beneficial because of their PRObiotic content.  HOWEVER, the probiotics of the mother and fermentation are killed off during the baking process, so sourdough does NOT contain probiotics.  However, it is rich in items that help feed your microbiome and contribute to long term gut health, but play less of a role in short term digestive comfort.  The Prebiotic Fiber found in sourdough acts as a fertilizer for our healthy gut bacteria. Whole grain sourdough breads will have a higher fiber and nutritional content than white flour sourdough. Sourdough also has a higher content of a different kind of fiber called Resistant Starch, which is another key player that contributes to a healthy microbiome.  Other great sources of resistant starch are cooked and cooler potatoes & rice.

In Summary, because of the long fermentation process, traditional sourdough bread is easier to digest than modern quick yeast breads.

Phytic Acid & Mineral Absorption

Phytic acid is a component of wheat products, and can bind to minerals and nutrients in our digestive tract, which impairs them from being absorbed by our bodies, making them less "bio-available". Specifically it binds to zinc, magnesium, calcium & iron which are extremely important minerals.  During the long fermentation process of sourdough, an enzyme (phytase) is produced which breaks down and greatly reduces the amount of phytic acid in sourdough.  This increases the bio-availability and absorption of the nutrients contained in whole wheat & thereby adds to the health benefits of sourdough bread.  So once again I will add that whole grain sourdough is nutritionally superior to sourdough made with white wheat.

*Phytates are categorized in the group referred to as "Anti-Nutrients".  Lectins, oxalates & phytoestrogens are some other anti-nutrients that have been discussed frequently by some in the nutrition space.

HOWEVER, anti-nutrients is another topic that deserves an entire blog discussion.  I believe that the negative hype is unwarranted and overblown, and should not be the immediate focus for most people.

Blood Sugar Stability

Now even though sourdough has many health benefits compared to modern quick rise breads, it has about the same impact on blood sugar as whole grain bread products.  Averaging about 54 on the Glycemic Index. So it doesn't qualify here as a superior health product for me.

Best Sources & What to Avoid

So, I think we have established well enough that traditional sourdough is a healthier choice than modern breads because of the long fermentation and leavening process. BUT, not all products labled as sourdough are created equal.  Commercial bread manufacturers cut corners to reduce the long fermentation time or eliminate it all together to save time and money, which then renders all of the health benefits mentioned above irrelevant!  They will use quick rise yeast and supplement it with sourdough powder, vinegar, baking soda or other leavening agents.  So how can we tell if it's a traditional sourdough we're buying with all of the health benefits we want?

1) Size & Shape - traditional sourdough will most likely be unique and not uniform - so if all the loaves look the same, read the ingredient list

2) Ingredients - it should say "culture" or "mother" somewhere on the ingredient list, beware of the key words mentioned above

3) Price - Beware of cheap breads.  Because of the time it takes to make a traditional sourdough it will usually be a little more expensive, but worth it.

4) Making it yourself or finding a local baker is probably the best way to go about it, but checking the artisan area in the bakery at a larger grocery store may also work.

I hope this was interesting and helpful for you, I certainly found it interesting to research! 

Let me know if you have any comments or questions! 

Resources & Related Articles:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7686800/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068548/

https://pubmed.ncbi.nlm.nih.gov/15631515/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600777/