Most bread is mildly acidic, with a pH between 5 and 6 on a scale where 7 is neutral. That puts it roughly in the same range as bananas or coffee with milk. White bread typically lands around pH 5.5, whole wheat bread around 6.1, and sourdough sits lower, closer to pH 4.0. None of these are strongly acidic, but the differences between bread types matter depending on why you’re asking.
pH Levels by Bread Type
White bread, the kind you’d grab off a grocery store shelf, has a measured pH of about 5.5. Whole wheat bread is slightly less acidic at around 6.1, which is close to neutral. The difference comes partly from the mineral content in whole grain flour, which acts as a mild buffer against acidity.
Sourdough is the outlier. During fermentation, bacteria produce lactic acid and acetic acid, steadily dropping the pH of the dough. A mature sourdough culture reaches a pH of roughly 4.0, and while baking raises it slightly, the finished loaf remains noticeably more acidic than a standard yeast bread. This is also what gives sourdough its tangy flavor and longer shelf life.
Quick breads made with baking soda tend to be less acidic than yeast breads. Baking soda is a base, so it raises the pH of the batter. If a recipe includes both baking soda and an acidic ingredient like buttermilk or yogurt, the two partially neutralize each other, but the final product still tends to be closer to neutral than a yeast-fermented loaf.
What Makes Bread Acidic
Fermentation is the main driver. When yeast and bacteria break down sugars in dough, they produce small amounts of organic acids as byproducts. In a standard commercial bread, yeast fermentation is relatively brief and controlled, producing only mild acidity. In sourdough, the process runs longer and involves a more complex community of bacteria, particularly lactic acid bacteria, that generate significantly more acid.
Whole grain flours add another layer. The bran portion of the grain is rich in a compound called phytic acid. When whole wheat flour is fermented, this phytic acid contributes to a slight drop in dough pH. Interestingly, the acidity created during fermentation also helps break down phytic acid itself, which frees up minerals like calcium, zinc, and iron that would otherwise be harder for your body to absorb. This is one reason long-fermented whole grain breads are considered more nutritious than their quick-rise counterparts.
Preservatives play a minor role too. Calcium propionate, one of the most common preservatives in packaged bread, works best when the bread’s pH is at 5.5 or below. It doesn’t dramatically change the acidity of the bread, but its presence is a clue that commercial bread is formulated to stay in that mildly acidic range, partly because that environment inhibits mold growth.
Bread and Acid Reflux
If you’re asking whether bread is acidic because of acid reflux or GERD, the pH of the bread itself is only part of the story. Plain white bread and whole wheat bread are generally considered well-tolerated foods for people with reflux. Their mild acidity is far less than what your stomach already produces (stomach acid sits between pH 1.5 and 3.5).
What matters more is how bread affects digestion. Bread is mostly starch, and your saliva starts breaking it down almost immediately. Salivary enzymes can hydrolyze up to 80% of bread starch within the first 30 minutes of reaching the stomach, before stomach acid deactivates them. This rapid breakdown means bread moves through digestion relatively quickly compared to fattier or more protein-dense foods, which is generally favorable for reflux.
Sourdough may be a different story for some people. Its lower pH means more acid hitting your esophagus and stomach. Some people with reflux tolerate it fine, while others find the tanginess aggravates symptoms. If reflux is your concern, plain white or whole wheat bread is the safer choice.
Bread on an Alkaline Diet
If you’re looking at bread through the lens of an alkaline diet, the relevant number isn’t pH but something called the Potential Renal Acid Load, or PRAL score. This estimates how much acid your kidneys need to process after you eat a food. A positive PRAL score means the food leaves an acid-forming residue; a negative score means it’s alkaline-forming.
All bread types have positive PRAL scores, meaning they’re classified as acid-forming foods in this framework:
- White wheat bread: 3.7
- Mixed wheat flour bread: 3.8
- Rye bread: 4.1
- Whole wheat flour bread: 1.8
- Coarse wholemeal bread: 5.3
- Pumpernickel: 4.2
- Rusk: 5.9
Whole wheat flour bread has the lowest PRAL score at 1.8, making it the least acid-forming option. This is because whole grains contain more alkaline minerals like magnesium and potassium compared to refined flour. Rusk and coarse wholemeal bread score highest, at 5.9 and 5.3 respectively. For context, fruits and vegetables typically have negative PRAL scores (alkaline-forming), while meats and cheeses score much higher than bread, often above 10.
Worth noting: PRAL scores reflect the metabolic effect of food on your urine pH, not on your blood pH. Your blood pH is tightly regulated and doesn’t meaningfully shift based on what you eat. The practical value of PRAL scores is debated, but if you’re following an alkaline diet plan, bread is a moderate acid-forming food, not a major one.
Which Bread Is Least Acidic
If you’re looking for the least acidic bread based on actual pH, whole wheat bread at roughly 6.1 is your best option among common varieties. It’s nearly neutral. White bread at 5.5 comes next, and sourdough at around 4.0 is the most acidic by a significant margin.
If you’re thinking in terms of metabolic acid load, whole wheat flour bread also wins with the lowest PRAL score of 1.8. So whether you’re measuring acidity directly or estimating its downstream effect on your body, whole wheat bread consistently comes out as the mildest option.