Health Benefits of Sourdough Bread

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Sourdough bread has a reputation for being healthier than other types of bread, but is that really the case? Some say absolutely, but the full picture isn’t entirely clear. 

If you wear a weighted vest, or are trying to eat more protein, or maybe even dabbling in tradwifery, you may also be sourdough-curious! I say this in jest (sort of!), but it feels like those who have interest in sourdough bread are also individuals who are focused on health and wellness and have a pulse on today’s trends. It’s interesting to consider how all of these things are intertwined…and why…

But first, what is sourdough bread?
There’s no scientific definition, because similar to many other baked goods, one product will differ somewhat from another. But the main identifying factor is that sourdough bread uses some sort of “starter” (a mixture of flour and water that grows wild yeast and lactobacilli, a bacteria that’s a product of fermentation) which is cultivated over time, in a unique environment, helping to leaven and flavor the bread. 

My kids may turn up their noses at the funky smell and taste, but I find sourdough to be the yummiest of all the breads. I love the crunch of the outside combined with the chewiness of the inside, and I have especially fond memories of carrying the most delicious hunks of Tartine Bakery’s famous sourdough while biking across the Golden Gate Bridge. (For those who know me, yes, I actually rode a bike!)

But how does sourdough bread work its healthy magic?
As with most foods, for sourdough to truly cement a place in our diets these days, it’s not enough for it to simply taste good. It’s has to be functional too. The proverbial “they” once said bread was cancelled, but now the pendulum has swung back around and “they” say sourdough has potential health benefits. So our ears have perked up!

How did this happen? You may have to ask the marketing masterminds that one, but let’s at least sift through the claims I hear most frequently and see how they hold up to scientific research:

1. Probiotics?  While technically true as noted above, the little buggers (like lactobacillus strains) aren’t alive by the time we eat them, rendering them irrelevant. But the fermentation process does produce prebiotic, or food for probiotics, which feeds the bacteria already swimming around in our GI tracts. Another tidbit about this claim is that it’s not unique to sourdough. Whole grain breads also contain prebiotics. 
   
2. Gluten-free? When making homemade sourdough bread, the fermentation process can break down a portion of the proteins, like gluten, before it’s baked. Studies have noted people’s responses after eating sourdough bread compared with other kinds of bread. In some, participants reported a decrease in gastrointestinal symptoms such as gas or bloating. In other studies, no significant differences were noted. As with all food, people’s response will vary depending on both how the bread is made and their own unique responses to eating it.
   
   For those who are sensitive to gluten (meaning they report bloating, pain, or other stomach discomfort after eating foods containing gluten), and limit it in their diets to reduce symptoms, sourdough bread may be easier to tolerate. But this is more anecdotal, and not a guarantee. 
   
   Those with celiac disease should avoid all sourdough bread, as it is not gluten-free, unless of course it is made with gluten free flour.
   
3. Lowers Glucose? Those who use the Glycemic Index (GI) to help manage blood sugar, may be intrigued by the idea that artisanal sourdough bread registers lower on the scale than whole grain bread. But not by much. On a scale of 0-100 sourdough sits around 30 while multigrain bread comes in around 40. And in over 50% of the studies comparing sourdough bread with whole grain breads, there weren’t any significant differences in glycemic response.
   
4. Weight Management? Beyond anecdotal reports (mostly seen on social media), there are no significant results showing that sourdough curbs appetite or decreases gastric emptying any more or less than other whole grain breads. 
   
5. Less bad stuff? In theory…and maybe…
   In vitro studies (meaning test tubes, not human) show that sourdough bread has lower FODMAPs than other breads. FODMAPs do have health benefits in their own right; but because they produce undigestible material, they may cause discomfort for those with IBS. So, while a bread with less FODMAP could be easier to tolerate for some, it is impossible to know how much less FODMAP. This will also differ from loaf to loaf.   
   
6. More good stuff? In theory…and maybe…
   In vitro studies also indicate vitamins and minerals are more bioactive in sourdough breads than others. But it is unclear how this translates to when humans ingest the bread and absorb it. Since everyone’s intestinal lining is different, there’s no realistic way to reliably measure this. Plus, if we eat a varied diet, we get enough vitamins and minerals without having to purposely try to get more from a slice of sourdough. Moreover, not all sourdough bread is whole grain anyway. A variety of flours can be used.

The Health Halo Around Sourdough Bread
Acknowledging that I’m a broken record here, it clearly needs to be repeated that nutritional studies are not well-known for precise results. It’s impossible to perform randomized controlled trials on specific foods or nutrients in an environment that mimics real life. (For example, are you eating a sandwich or topping the sourdough bread with something? Or do you only eat plain slices of bread with nothing on the side? Is this something you eat everyday?).

When you hear someone making definitive health claims about specific foods, that should be a red flag to not automatically believe whatever the person says next. Even if scientific studies show associations or trends between foods and health outcomes, it’s typically more general. For example, “it’s widely accepted that eating five servings of fruits and vegetables a day improves overall diet quality and promotes well-being.” Or, “a diet high in ultraprocessed foods is associated with weight gain.” These claims are based on a broad range of dietary patterns averaged over time, and are not pinpointing a singular food item like a zucchini, or potato chips, respectively.

Key Takeaways

• Baking sourdough bread at home is an on-trend hobby that can be tricky but exciting to master. It’s also quite delicious!
• Some studies suggest sourdough bread is better for overall gut health in terms of tolerability, glucose management, bacterial diversity, and better absorption. None of these claims are definitive.
• A slice or two of sourdough bread is a very small drop in the bucket of daily life, exposures, and food you eat. The impact on your health cannot be directly correlated. 
• The bloated health halo around sourdough bread is not rooted in reality, and scientific studies do not support the amount of hype it gets on social media.