Sourdough Bread: Nutrition, Gluten and Is It Healthy?

Sourdough bread is bread leavened by a sourdough starter, a fermented mix of flour and water, instead of only packaged baker’s yeast. USDA has no separate sourdough entry; its closest one, French or Vienna bread (which USDA notes includes sourdough), lists about 77 calories, 3 grams of protein and 171 milligrams of sodium per ounce. The short answer to the gluten question: sourdough made with wheat, rye or barley flour still contains gluten. This guide covers sourdough bread nutrition, how the fermentation works, whether sourdough bread is healthy, and how to read the label.

Peptide Labs does not sell sourdough bread or any bread product. This article is general nutrition information, not medical advice.

What is sourdough bread?

Sourdough is one of the oldest ways to raise bread. A 2023 review in Critical Reviews in Food Science and Nutrition describes sourdough as flour fermented by mixed communities of lactic acid bacteria and yeasts. Traditional bakers keep a starter going by “backslopping”: they mix part of the previous batch into fresh flour and water. Some bakeries instead start the dough with selected starter cultures. The yeasts make the gas that lifts the loaf, and the bacteria make the acids behind the sour taste.

Store loaves vary. Some can be made with a starter alone, others combine a starter with added yeast, and the flour can be white, whole wheat, rye or a blend. The ingredient list is the only reliable guide: it names the flours, any added yeast, and whether the flour is enriched. Our fermented foods guide covers other foods made with live cultures, and our rye bread guide covers dark, rye-based loaves.

Sourdough bread nutrition (USDA)

The table compares one ounce of three breads in USDA SR Legacy data. The sourdough row is USDA’s French or Vienna bread entry, the closest match available, so read it as an estimate. Slice sizes differ a lot between loaves, so the ounce is the fairer comparison; check your own bread’s Nutrition Facts label for the slice you eat.

In USDA data, the sourdough-type bread is close to white bread in calories, carbohydrate and fiber, and a little higher in sodium. Per 100 grams, USDA lists 602 milligrams of sodium for it. Whole-wheat bread has nearly three times the fiber per ounce and much more manganese (27% of the Daily Value in USDA data) because the whole grain keeps the bran and germ. The folate in the white and sourdough-type entries comes largely from enriched flour: under FDA’s standard in 21 CFR 137.165, enriched flour has added thiamin, riboflavin, niacin, folic acid and iron. A loaf made with unenriched flour will not carry those additions, so check the ingredient list for the word “enriched”. Our whole wheat flour guide explains the flour side in detail.

Is sourdough gluten free?

No. Sourdough made with wheat, rye or barley flour contains gluten. NIDDK, part of the National Institutes of Health, describes gluten as a protein found naturally in wheat, barley and rye, and names bread and pasta as common foods that contain it. The Celiac Disease Foundation lists breads among the foods that contain gluten as well. Fermentation changes the flavor and texture of wheat dough, but an ordinary sourdough loaf is still a wheat food.

FDA labeling rules point the same way. Under 21 CFR 101.91, a food labeled gluten-free must contain less than 20 parts per million of gluten. For fermented foods, which are hard to test accurately, FDA requires the maker to keep records showing the food was gluten-free before fermentation and that cross-contact was controlled. In other words, fermenting wheat flour does not by itself make bread eligible for a gluten-free label.

Two details explain the confusion. First, researchers have tested special processes: in a 2010 pilot study, selected lactobacilli plus fungal enzymes broke wheat gluten down to below 10 parts per million, and 8 patients with celiac disease ate the resulting baked goods. The authors wrote that such wheat products should not be recommended for people with celiac disease until a formal trial has been done, and this is not how bakery sourdough is made. Second, sourdough made without wheat does exist: a 2021 review describes sourdough methods applied to gluten-free flours. Those loaves start with no gluten grains and should say gluten-free on the label.

If you have celiac disease or another reason to avoid gluten, NIDDK says a doctor or registered dietitian can guide the diet, and doctors don’t recommend starting a gluten-free diet before testing. Our foods with gluten guide lists hidden wheat, barley and rye sources, and naturally gluten-free grains such as buckwheat and quinoa are covered in their own guides.

Is sourdough bread healthy?

There is no single answer, because the flour and the portion matter more than the starter. In USDA data, a white-flour sourdough-type bread is nutritionally close to ordinary white bread: mostly carbohydrate, little fiber, moderate sodium, and B vitamins and iron from enrichment. A whole-grain sourdough brings the fiber and minerals of whole grains. The Dietary Guidelines for Americans 2020-2025 list white breads among refined grains and whole-wheat bread among whole grains, and the 2025-2030 edition tells Americans to prioritize fiber-rich whole grains and cut back on highly processed refined carbohydrates such as white bread. Our refined carbs guide explains that difference, and our high fiber foods guide shows other ways to add fiber.

Fermentation does change some carbohydrates. Wheat and rye contain fructans, one of the FODMAP groups that Monash University researchers describe. A 2018 review in the journal Foods explains that sourdoughs with specific FODMAP-targeting properties can markedly reduce FODMAPs in bread. That does not mean every loaf sold as sourdough is low in FODMAPs; the result depends on the microbes and the process. If you follow a low FODMAP diet with a dietitian, ask them how sourdough fits.

• Read the flour list: “whole wheat” or “whole grain” first means more fiber than “enriched wheat flour”.
• Compare sodium using the %DV on the Nutrition Facts label; FDA counts 20% DV or more per serving as high.
• Check how much a slice weighs, since large bakery slices can be well over an ounce.
• Look for a gluten-free label only if you need one; a plain sourdough label does not mean gluten free.

Baking sourdough at home

Home bakers often taste dough as they go. FDA advises against eating or tasting raw flour, dough or batter, because most flour is a raw food that has not been processed to kill germs, and baking or cooking is what kills them. CDC has investigated outbreaks of E. coli infections linked to raw flour in 2016, 2019, 2021 and 2023. CDC advises washing your hands after handling flour. Wheat is also one of the nine major food allergens that US law requires labels to declare, which matters if you share homemade bread.

Sourdough often appears alongside pasta on the same table; our pasta guide compares enriched, whole wheat and gluten-free pasta in USDA data.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: Pasta Nutrition: Enriched, Whole Wheat and Is Pasta Healthy?, Rye Bread: USDA Nutrition per Slice, Research and How It Compares, Fermented Foods: List, Benefits and Live vs Pasteurized, Bagels: Nutrition Facts, Are Bagels Healthy, and Bagel vs Bread, Types of Bread: 25 Breads Compared per Ounce in USDA Data, Sourdough vs Whole Wheat: How USDA Data Compares Them.