Key Takeaways
- Sourdough fermentation may make bread easier to digest and improve mineral availability.
- Sourdough can still raise blood sugar and may contain significant sodium.
- The health benefits depend heavily on the flour, fermentation process, and portion size.
Sourdough has become the bread that people feel good about buying and has become one of the most popular breads on cafe menus, across social media, and within the growing “crunchy mom” community. It is also a common food item on lists about fermented foods for gut health. Sourdough bread has a unique taste, being both tangy and crisp whilst also being chewy. Additionally, sourdough is purported as one of the healthier alternatives to white bread, with a plethora of health benefits.
Many home cooks, bakers, and amateur chefs enjoy making sourdough bread, as it consists of 4 ingredients (flour, water, salt, and sourdough starter) at its very core. This blog is for those who want to know: is sourdough bread healthy for your gut health, or is it just another fad diet food (like the military diet)?
What Is Sourdough Bread?
Sourdough bread is made by leavening dough with a sourdough starter, a living culture of lactic acid bacteria and wild yeast, rather than with commercial added yeast alone [1].
The bacteria produce lactic acid and acetic acid during the fermentation process, which lowers the pH of the dough, develops the tangy flavor, and changes the texture [2]. Sourdough bread is considered a healthier option due to its long fermentation process [3]. When dough pH drops below about 4.5, cereal enzymes activate and certain compounds in the flour start breaking down [4].
| Sourdough type | Flour fermented | Live microbes in dough |
|---|---|---|
| Type I (sole leavening agent) | 20 to 30%, over 6 hours | Yes, high activity |
| Type II (acidification and flavor) | 10 to 20% | Yes, lower activity |
| Dried sourdough (added powder) | 3 to 5% | None, killed during drying |
Traditional type I sourdough, used as the sole leavening agent, ferments 20 to 30 percent of the flour for more than six hours. Dried sourdough, added at 3 to 5 percent, contains no living microbes at all and contributes flavor without any metabolic activity in the dough [4].
Nutritional Information of Sourdough Bread
When it comes to asking, “Is sourdough bread healthy?” the nutrition depends almost entirely on the flour, for instance, whole-grain flour, almond flour, or even the flour used in multigrain bread.
A loaf built from refined white flour has broadly the nutrition profile of any other white bread. A loaf built from whole-grain flour or whole rye carries more fiber and minerals.
Approximate values for a typical 50 g slice, which vary depending on recipe, hydration, and loaf size:
| White flour sourdough | Whole-grain sourdough | |
|---|---|---|
| Calories | roughly 120 to 150 | roughly 120 to 140 |
| Protein | 4 to 6 g | 5 to 7 g |
| Fiber | 1 to 2 g | 3 to 4 g |
| Added sugar | typically none | typically none |
Traditional sourdough uses simple ingredients: just flour, water, salt, and starter. Many commercial sandwich bread products, including some multigrain bread and wheat bread lines, include added sugar, honey, or syrups.
Glycemic Index of Sourdough Bread
The glycemic index (GI) is a system used to describe how quickly a carbohydrate-containing food raises blood sugar after it is eaten. Foods are generally given a GI value from 0 to 100, with glucose used as the reference at 100. A higher glycemic index means the carbohydrates are digested and absorbed more rapidly, which can lead to a faster rise in blood sugar. In comparison, foods with a lower GI tend to produce a slower increase in blood glucose levels [5]:
| Bread | Glycemic index |
|---|---|
| Whole-grain rye sourdough | 53 |
| Whole-grain rye | 58 |
| Whole-grain wheat | 74 |
| White wheat flour | 75 |
| French baguette | 95 |
3 Potential Health Benefits of Sourdough Bread
Sourdough bread, which has a long fermentation process, can change how certain compounds in wheat bread and whole-grain bread are broken down, potentially making sourdough easier to digest while improving the availability of certain nutrients. But is sourdough bread healthy? Below are some health benefits of consuming sourdough bread.
1. Easier to Digest
Sourdough bread can contain up to 75% fewer FODMAPs. Wheat and rye contain fructans, a type of FODMAP that ferments rapidly in the colon and triggers bloating, gas, and abdominal discomfort in sensitive people.
In fact, sourdough fermentation degrades them and may lower glycemic index, with reported reductions ranging from under 50 percent to more than 95 percent [1]. The long fermentation process helps break down gluten proteins, which may make sourdough easier to digest for many people.
2. Mineral Absorption
Phytic acid in grains binds zinc, iron, magnesium, and calcium, limiting absorption. Sourdough acidification solubilizes phytate salts while keeping cereal phytases near their optimal activity, and consumption of sourdough bread increased mineral absorption in rats compared with yeast-fermented bread [1]. The human data are less direct, but this is the most mechanistically solid of the benefits of sourdough.
3. Lower Acrylamide
Acrylamide forms during baking and is classified as a contaminant. Sourdough fermentation, unlike other types of bread, decreases rather than increases its formation, with studies reporting reductions of roughly 25 to 59 percent [1].
3 Potential Risks of Eating Sourdough Bread
Although consuming sourdough bread may have many benefits, there may be some potential risks. Below are some commonly associated risks with the consumption of sourdough bread.
1. Allergic Reaction from Gluten
Sourdough lactobacilli do degrade gluten peptides, and experimental sourdoughs using fungal proteases can achieve near-complete protein degradation.
But sourdough products available on the market are generally not processed this way, and there is no data supporting the claim that sourdough bread reduces the risk of developing celiac disease [1]. If you have celiac disease, ordinary sourdough is unsafe. You need certified gluten-free bread under 20 ppm gluten.
For gluten-free alternatives, like gluten-free snacks or even gluten-free meal plans, read our other blogs.
2. High in Sodium
Sourdough typically contains 1.8 to 2 percent salt by flour weight, which is not unusual for bread but adds up across several slices a day, especially if you eat several slices of bread throughout the day or regularly consume store-bought sourdough alongside other salty foods.
Alternatively, our blog on a 7-day low-sodium diet meal can offer some tips to lower your sodium consumption.
3. Can Raise Blood Glucose
Sourdough is still a carbohydrate-rich food, so it can increase blood glucose, particularly when made primarily with refined flour or eaten in large portions. Its effect can vary considerably depending on the bread flour, fermentation process, portion size, and other ingredients used.
Sourdough made primarily from refined white flour, for example, may affect blood glucose differently from whole-grain bread, grain bread, or sprouted grain bread.
Foods You Can Eat with Sourdough Bread
Sourdough bread is an extremely versatile food and can be eaten any time of the day. Below is a list of food items commonly paired with sourdough bread, which may maximize the health benefits of your meal.
Other Foods That Benefit Your Gut Health
Dietary variety is generally more important for supporting the gut microbiome than relying on any single food. Eating a diverse range of plant-based food sources, including fruits, vegetables, legumes, whole grains, nuts, and seeds, provides different types of fibre and other compounds that can support a diverse community of gut microorganisms. Below are different foods that may be other gut health-friendly alternatives.
| Category | Foods and ingredients |
|---|---|
| Fermented dairy | Yogurt with live cultures, kefir |
| Fermented vegetables | Kimchi, sauerkraut, fermented pickles |
| Other fermented foods | Tempeh, miso, natto, kombucha |
| Whole grains | Oats, barley, rye, whole wheat, brown rice, quinoa |
| Legumes | Lentils, chickpeas, black beans, kidney beans, peas |
| Prebiotic vegetables | Garlic, onions, leeks, asparagus, artichokes, chicory |
| Cruciferous vegetables | Broccoli, cauliflower, cabbage, Brussels sprouts |
| Leafy vegetables | Spinach, kale, arugula, Swiss chard |
| Gut friendly fruits | Kiwifruit, bananas, apples, pears, oranges, berries |
| High fiber fruits | Raspberries, blackberries, figs, prunes, avocado |
| Nuts | Almonds, walnuts, pistachios, peanuts |
| Seeds | Chia seeds, flaxseeds, pumpkin seeds, sunflower seeds |
Final Words: Is Sourdough Bread Healthy?
Healthy bread should have low or no added sugar, and aim for breads with under 200 mg of sodium per slice. So, is sourdough bread healthy? Yes and no. Anything in excess can be unhealthy, and the health benefits of sourdough bread depend on the ingredients and the amount you consume.
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