Why Our Digestive Systems Digest Sourdough Bread

Why Our Digestive Systems Digest Sourdough Bread

In January, I went to a low FODMAP cooking class hosted by Foodicine Health and registered dietician, Kate Scarlata. In addition to learning helpful cooking tips and eating the wonderful food prepared by Chef Tim Maslow, Kate spoke about the low FODMAP diet and facilitated a Q & A session. During the session, Kate mentioned that sourdough bread made without added commercial yeast has been shown to be low FODMAP. This information was a life changer for me. If your choice of bread has been limited to the typical gluten-free bread from the grocery store then you probably understand how glorious it is to be able to have real sourdough bread. If you have not, then try one slice and you will probably get it very quickly. Sourdough bread has in general been found to be easier on the digestive system and people find that they do not get bloated after eating it. I know I haven’t. Additionally, there are research studies demonstrating that sourdough bread may be a good choice for people with irritable bowel syndrome, non-celiac gluten sensitivity, and diabetes and that it can help improve gut healing in celiac patients. Also, sourdough bread is filled with vitamins and minerals and in my opinion, tastes great.

What makes sourdough the wonder bread for our digestive systems? Let’s start with what  sourdough is made of and a brief history. Sourdough culture is a mixture of flour and water, which uses the wild yeast and lactobacillus bacteria present in the flour and air to leaven the dough and produce a sour and tangy flavored bread. More flour and water is periodically added to maintain the culture until a portion of it is used to create the dough.

Although the first loaf of sourdough bread was found in Switzerland from about 3500 BC, sourdough bread most likely began in Egypt much earlier. Egyptians made flat bread and the theory for how sourdough bread began is that some dough may have been left out for too long and started bubbling and rising from the wild yeast present in the air or from the brewery, which usually shared space with the bakery. When that dough was baked, the baker discovered a light, puffy, and crusty bread. This method of baking later spread to Greece, Rome, other parts of Europe, and then to California, Alaska, and Western Canada during the 19th century gold rush. The Boudin family came from France and started the Boudin Bakery in San Francisco during this time. The bakery, which still exists today, uses the same sourdough starter that they used to feed miners in 1849. When traveling, prospectors and explorers would wear a pouch of starter culture around their necks to ensure they would always have something to eat. Eventually, with the discovery of commercial yeast and food manufacturing processes, such as the Chorleywood bread process in the 20th century, the slow rising technique used to make sourdough bread with wild yeast and time, sped up.

In a factory, bread can go from flour to finished bread in three hours. Instead of bread just being made from flour, water, and salt, this quick process requires the addition of more yeast and gluten, fat for softer crust, reducing agents for stretchy dough, soya flour for more volume and softness, emulsifiers for larger, softer, and less stale bread, and preservatives, enzymes, and processing aids to keep the bread on the shelf longer. This is drastically different from sourdough bread, which goes from starter culture to risen dough in 24 hours, and then it needs to be baked. The advantage of allowing a long fermentation process is that the sourdough bread is given time for the flavors to develop and vitamins to be made. It also makes bread that is easier on our digestive system. Below are some of the reasons why.

  • The bacteria and acidic pH level found in the sourdough culture can weaken the gliadin and glutenin proteins (which make up gluten) so it is easier to digest.
  • The yeast will consume the fructans (a polymer of fructose molecules) present, resulting in lower FODMAP levels.
  • Phytic acid is found in wheat and sequesters calcium, magnesium, iron, and zinc and inhibits enzymes that help us digest by metabolizing the proteins and starch in our stomach. The yeast and bacteria are able to pre-digest the phytic acid, making the necessary minerals available for us to absorb and for the enzymes to be able to break down the proteins and starch so we can better digest the sourdough bread.
  • The bacteria forms lactic acid, which helps create the characteristic flavor of the bread and is known to reduce the rate that glucose enters the bloodstream. Sourdough bread has a lower glycemic index, preventing a spike in insulin release.
  • The bacteria make antioxidants, lunasin (a cancer prevention protein), and anti-allergenic compounds, helpful in autoimmune diseases.
  • The amino acid, asparagine is a precursor for the carcinogen acrylamide found in some bread crusts. Asparagine is reduced during the time it takes for the sourdough to rise.

Some of the studies including the ones involving celiac patients are still in the early stages but there is both research and anecdotal evidence that sourdough bread made the traditional way is generally better for our digestion. Also, whether we know for sure if the chemicals and preservatives we are adding to our foods is leading to an increase in food intolerances and/or chronic diseases, I would rather just eat real food.

1. http://www.sourdough.co.uk/the-history-of-sourdough-bread/
2. http://www.kitchenproject.com/history/sourdough.htm
3. https://www.theguardian.com/lifeandstyle/2016/mar/23/sourdough-bread-gluten-intolerance-food-health-celiac-disease
4. http://blog.katescarlata.com/2015/11/10/lets-talk-about-sourdough-bread-fodmaps/
5. http://www.med.monash.edu/cecs/gastro/fodmap/low-fodmap.html#5
6. http://www.ncbi.nlm.nih.gov/pubmed/20975578
7. http://www.sourdough.co.uk/why-is-it-that-i-can-digest-sourdough-bread-and-not-commercial-bread/
8. http://www.breadmatters.com/index.phproute=information/information&information_id=34
9. https://www.theguardian.com/lifeandstyle/2014/aug/12/rise-sourdough-bread-slow-fermented-health-benefits

Photo by Brooke Cagle on Unsplash



  1. I’ve heard a little bit about this, as well! I wonder if there are any bakeries in the area that bake sourdough without commercial yeast. I may have to ask 🙂 I used to love sourdough for breakfast with butter and raspberry jam.
    I have indulged myself some on the bread front this year–I got the America’s Test Kitchen Gluten-Free Cookbook, and their gluten-free sandwich bread is seriously really good, and only rises once! Sorry, that sounded like a paid advertisement or something, but I swear it isn’t.
    How was Kate Scarlata? Had you ever gotten to see her speak before?


    • Hi Joyce! When Pigs Fly is a great bakery that sells a German Country Sourdough bread with no yeast. They simply use flour, water, and salt and the bread is amazing. I buy a couple of loaves and freeze them and they freeze very well. They ship bread if you cannot find a place near you that sells bread without yeast. Thanks for the recommendation for the America’s Test Kitchen gluten-free sandwich bread, I will have to check it out. Gluten-free girl also has a great Thanksgiving gluten-free sandwich bread that is easy and tastes great. Kate is wonderful. I met her at the cooking class and then went to a GI conference she ran and she is smart, knowledgeable, warm, kind, and easy to talk to. I consider her my FODMAP guru : )


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