Dozens of varieties of bread line store shelves and fill cookbooks, though some are healthier than others.

Certain types are high in fiber, vitamins, and minerals, while others are made from refined grains and offer little in terms of nutrition.

Naturally, you may wonder what kind of bread is healthiest.

Sourdough is made through a fermentation process that relies on naturally occurring yeast and bacteria to make the bread rise.

Fermentation helps reduce the number of phytates, also known as phytic acid, that bind to certain minerals and impair their absorption.

One study found that sourdough fermentation helped decrease phytate content by over 50% compared to using conventional yeast.

Sourdough may also be easier to digest than other breads, possibly due to its prebiotics, as well as the probiotics created during the fermentation process.

Probiotics are healthy bacteria found in your body and certain foods, whereas prebiotics are non-digestible fibers that feed these bacteria. Getting enough of each promotes good gut health and digestion.

Finally, sourdough bread is thought to have a low glycemic index (GI), a measure of the impact a food has on blood sugar.

This is because the bacteria in sourdough may help decrease the rate at which starch is digested, making this bread less likely to cause a big spike in blood sugar.

Sourdough can be made with both whole-wheat and white flours. While each provides the benefits associated with fermentation, whole-wheat sourdough has more fiber, iron, and other nutrients.

One slice (47 grams) of whole-wheat sourdough gives:

Calories: 120
Protein: 4 grams
Fat: 0 grams
Carbs: 20 grams
Fiber: 3 grams

Sourdough bread is made through a fermentation process that boosts its digestibility, improves the availability of certain nutrients, and lowers its blood sugar effects.