Sourdough Vs. Whole Grain Bread: Which Is Better for You, According to Dietitians

Sourdough bread is typically baked in a rustic style, producing a large round or oblong loaf. Meanwhile, there are plenty of whole-grain breads available at the grocery store in a standard-sized sliced loaf. So, in order to compare the nutritional content, the info below is for one large slice of sourdough and two standard slices of whole grain.

Sourdough nutrition

Per the U.S. Department of Agriculture (USDA), one medium slice (which is around 59 grams) of sourdough bread contains:

• 188 calories
• 7.67 g of protein
• 1.26 g of fat
• 36.5 g of carbohydrates
• 1.83 g of fiber

Whole-grain bread nutrition

According to the USDA, two slices (about 52 g) of whole grain bread contain:

• 138 calories
• 6.96 g of protein
• 2.2 g of fat
• 22.6 g of carbohydrates
• 3.84 g of fiber

“Sourdough bread is unique because it’s made through a natural fermentation process using wild yeast and bacteria,” explains Samantha Peterson, M.S., R.D.N., a functional medicine dietitian and founder of Simply Wellness. “That fermentation changes how the bread is digested and can offer several health benefits.” The first of these is that it is broken down more slowly than other types of bread, making it a smart choice for people who need to watch or manage their blood sugar levels. “Compared to conventional bread, sourdough tends to have a lower glycemic response, meaning it may lead to a slower, more gradual rise in blood sugar,” says Peterson. In fact, a study published in Critical Reviews in Food Science and Nutrition found that sourdough bread may have a lower impact on blood glucose levels than non-fermented bread at both 60 and 120 minutes after consumption.

“Sourdough is often easier to digest for some people,” says Emer Delaney, R.D., P.T., a registered dietitian and founder of My Private Dietitian. That’s because the fermentation process partially breaks down the gluten and some other compounds in bread that can be difficult to digest and can cause bloating in people with sensitive stomachs or other GI uses. “Fermentation can also reduce phytic acid, which may improve how well minerals like iron, zinc, and magnesium are absorbed,” Delaney adds. Phytic acid is a compound known as an anti-nutrient that can hinder nutrient absorption in some cases. However, research in the journal Life found that fermentation may reduce the concentration of anti-nutrients in foods, making minerals more available for absorption and use in the body.

“Not all sourdough is created equal,” says Peterson. “Some sourdough breads are made with refined white flour, which lowers fiber content and reduces the overall nutritional value. Others are labeled “sourdough” but are made with commercial yeast and minimal fermentation, which limits many of the digestive and metabolic benefits.” All that to say, be picky when buying sourdough if you want to get the above perks.

“While fermentation can partially break down gluten, sourdough still contains gluten unless it’s made from gluten-free flours,” adds Delaney, noting that it’s not a safe option for people with celiac disease. What’s more, despite the fact that it is lower on the glycemic index than some other types of bread, “sourdough is still a carbohydrate source,” Peterson says. “Portion size matters, as does how it is balanced within a meal. Pairing it with protein and healthy fats helps support blood sugar stability.”

A true whole-grain bread is baked using all three parts of the grain, says Delaney. “That includes the germ, which is the inner part rich in vitamins, minerals, and healthy fats; the endosperm, which is the middle part containing starch, and the tough exterior fiber-rich shell, known as bran.” Starting with the goodness contained in the germ, whole-grain bread is much richer in micronutrients than bread made with refined or processed flour. In fact, research has found that mineral levels in breads made with refined flour can be up to 72% lower than bread made with whole wheat flour. “Whole-grain breads provide important nutrients such as B vitamins, which support energy metabolism, iron, magnesium, and antioxidants that help protect cells from oxidative stress,” Peterson says.

Then there’s the high fiber content in the bran. “Fiber slows digestion, feeds your gut bacteria, helps you feel fuller for longer, and helps to steady your blood sugar,” says Delaney. The combination of these features links whole-grain bread to a reduced risk of various chronic illnesses. One study in Preventive Nutrition and Food Science found that people with diabetes who ate whole grain bread daily showed better blood sugar regulation, lower cholesterol levels, and healthier fat profiles than those who didn’t eat it, while separate research in Nutrition Journal linked whole grain intake to a reduced risk of type 2 diabetes, stroke, and certain cancers.

“While whole grain bread is nutrient-dense, it doesn’t work equally well for everyone, particularly when it comes to digestion and blood sugar response,” says Peterson. The high fiber content and presence of gluten and fructans may make it difficult to digest for some people, potentially leading to bloating or GI discomfort. “Even whole-grain bread can raise blood sugar if eaten on its own. Pairing it with protein and healthy fats helps slow digestion and support more stable energy levels,” Peterson adds.

Then there’s the fact that not all breads that are labeled as whole grain truly are whole grain. Some may still be processed or contain added sugars, sodium, or other ingredients despite what it says on the front of the package. Peterson recommends choosing one that lists a whole grain, such as “whole wheat” or “whole grain rye” as the first ingredient and contains minimal added sugars or fillers.

“For weight loss, whole grain breads are usually the better default because higher fiber helps you feel fuller for longer and supports appetite control,” says Delaney, which may help towards a calorie deficit diet (a calorie deficit is needed to lose weight). However, she notes that whole-grain sourdough does exist—and if you can find it, it’s likely the best option. That way, you get the fiber from the whole grains and the digestive perks from the fermentation process, both of which can support weight loss, if that’s your goal.

“There’s no universal ‘healthier’ option—both sourdough and whole grain bread can support good health when chosen and eaten thoughtfully,” Peterson says. “Sourdough may be a better fit for people with digestive sensitivities or those who notice blood sugar swings with conventional breads. Whole grain bread may be ideal for individuals focused on increasing fiber intake, supporting heart health, and meeting daily nutrient needs.”

As mentioned above, if you can find whole wheat sourdough, then there’s very little difference between the two in terms of health benefits. “Ultimately, the healthiest bread is one that fits your digestion and energy needs, supports stable blood sugar and satisfaction, and feels sustainable within your lifestyle,” says Peterson.