The short answer
Acid-forming foods, the ones people mean when they search for an acidic foods list, are foods with a positive PRAL score. Hard cheese tops the chart, followed by poultry, red meat, fish and egg yolks. Nuts, seeds and grains come next with smaller scores. Of everything we calculated, parmesan scored highest, at about +25 per 100 grams. Cooked white rice, at under +2, barely registers.
PRAL means potential renal acid load. It is the estimate Thomas Remer and Friedrich Manz published in 1995 for how much acid a food leaves for the kidneys to clear once it has been digested. We worked out every number below ourselves from USDA FoodData Central nutrient values, using their formula, so you can check the math. Treat the numbers as a ranking, not a lab result.
This page is the other half of our alkaline foods list, which covers the vegetables and fruit that score below zero. Read the two together. A meal is never only one end of the chart, and the useful question is how the plate adds up.
Acid-forming is not the same as acidic
The word acidic causes most of the confusion here. Taste is not the measure: a lemon is sour, but it leaves a small base-forming load behind. Neither is the pH in the glass. Cola is one of the most acidic drinks on a grocery shelf: a 2016 study in the Journal of the American Dental Association measured Coca-Cola Classic at pH 2.37. Its PRAL is about +0.2, which is practically zero, because a can of cola carries little protein, a little phosphorus and almost no minerals.
That gap matters for two different reasons. Drink pH is a real concern for your teeth. The same dental study found that most bottled drinks it tested were below pH 4.0, the range where tooth enamel can start to soften. PRAL is about something else entirely: what the kidneys handle after digestion. It does not predict the pH of your blood. Healthy bodies keep blood pH in a narrow band of about 7.35 to 7.45 regardless of diet, as a 2012 review in the Journal of Environmental and Public Health points out. Diet shows up in urine, which is what Remer and Manz measured.
On this site, alkaline and acid-forming are cooking labels that describe where a food sits on this chart. They are not claims about your body chemistry, and an acid-forming food is not a bad food.
How the numbers were calculated
The formula uses five nutrients per 100 grams of food. Protein and phosphorus raise the score. Potassium, magnesium and calcium lower it. PRAL (mEq per 100 g) = 0.49 × protein (g) + 0.037 × phosphorus (mg) − 0.021 × potassium (mg) − 0.026 × magnesium (mg) − 0.013 × calcium (mg).
For each food we used the USDA SR Legacy record for the plain item, cooked the way most people eat it unless the label says raw or dry, and rounded to one decimal place. Older published PRAL tables were built from older nutrient data, so they will not always match ours to the decimal. What should match is the order: cheese and meat at the top, grains in the low single digits, drinks around zero.
Keep two limits in mind. 100 grams is a lab convenience. It is about two eggs, a small chicken breast or a heaping cup of cooked pasta, but it is far more parmesan than anyone grates onto a bowl of soup. And the formula leaves out factors such as sulfur-containing amino acids and how much of each mineral is absorbed. That is why Remer and Manz called the result a potential load.
The acid-forming foods chart, highest to lowest
Every value below is in mEq per 100 grams, calculated from USDA FoodData Central. Positive means acid-forming. The groups are sorted from highest to lowest score, and so is each list.
Cheese
Hard, aged cheeses score the highest of any food we calculated: Parmesan, hard +24.7; Swiss +20.5; cheddar +17.3; mozzarella, whole milk +15.3; feta +11.2; cottage cheese, creamed +7.9; cream cheese +2.7. Aging removes water, which concentrates protein and phosphorus in each gram, so the firmer the cheese, the higher the number. Cream cheese is mostly fat, so its score is small. A tablespoon of grated parmesan weighs about 5 grams, which works out to roughly +1.2 for the spoonful.
Poultry and meat
Lean cooked meat comes next: Chicken breast, roasted +17.3; turkey, roasted +16.5; beef top sirloin, lean, broiled +14.7; pork loin, lean, roasted +13.3; beef patty, 85% lean, broiled +12.6; Italian pork salami +11.3; sliced ham +6.9. Lean cuts score higher than fattier ones per 100 grams, because fat carries no protein and no phosphorus. The cured meats score lower than you might expect, but they are high in sodium, which PRAL does not count.
Fish and shellfish
Seafood sits in the same range as meat: Sardines, canned in oil with bones +15.9; shrimp, cooked +13.2; light tuna, canned in water, no salt added +12.7; cod, cooked +9.9. Our alkaline list gives cooked farmed salmon at +11.1. Canned sardines would score even higher if their soft bones did not add calcium, which pulls the number down a little. Cod is lean and white and lands lowest of the four.
Eggs
An egg splits into two very different halves: Yolk, raw +18.1; whole egg, hard-boiled +9.0; white, raw +2.1. Nearly all of the phosphorus is in the yolk, so the yolk scores high. Egg white is mostly protein and water and scores low. One large egg weighs about 50 grams without the shell, so a hard-boiled egg is roughly +4.5.
Nuts and seeds
Nuts and seeds land in the middle of the chart: Sunflower seed kernels, dried +11.6; peanuts, dry-roasted +6.7; peanut butter, smooth +6.6; cashews, dry-roasted +6.4. These foods are rich in magnesium and potassium, but they carry enough protein and phosphorus to stay above zero. A typical serving is 28 to 30 grams, so a handful of cashews is closer to +2 than +6.
Grains, bread and pasta
Cooked grains score low because cooking adds water: Pasta, cooked +3.5; rye bread +3.3; white bread +2.8; quinoa, cooked +2.3; oatmeal, cooked with water +1.8; white rice, cooked +1.7. The wheat foods, pasta and bread, sit a little above rice and oatmeal because wheat carries more protein. Dry oats belong near the top of the chart, which our alkaline list explains. In the bowl they score only about +2, since most of the weight is water.
Drinks that taste acidic but score near zero
These four are on the list because people often ask about them, not because they are acid-forming: Cola, regular +0.2; beer 0.0; black tea, brewed −0.8; coffee, brewed −1.0. Coffee and tea come out slightly base-forming because brewing pulls potassium out of the leaves and beans, and they contain almost no protein. The dental study above measured brewed coffee at a pH of about 5.1, so it is mildly acidic in the cup, but it is not acid-forming by PRAL.
What the chart does and does not tell you
A high number is not a warning label. Fish, eggs, poultry, yogurt, cheese and whole grains are all part of the healthy eating patterns in the Dietary Guidelines for Americans. They supply protein, iron, zinc, vitamin B12 and other nutrients that vegetables alone do not provide in the same amounts. A positive PRAL says only that, gram for gram, a food carries more protein and phosphorus than balancing minerals.
Researchers have looked for harm. One idea was that an acid-forming diet weakens bones. A 2011 systematic review and meta-analysis in Nutrition Journal, by Fenton and colleagues, applied formal causality criteria to that research and did not find support for dietary acid load causing osteoporosis. We mention it so you can see that the chart is a cooking tool, not a health scorecard.
The practical point is balance. PRAL values add up across a meal, which means a few spoonfuls of cheese or a serving of chicken can sit inside a plate that still comes out near zero, or below it, once the vegetables, potatoes and fruit are counted.
Balancing a plate with both ends of the chart
You do not need to cut anything out to cook from the lower end of the chart. Here is a worked example using the numbers on this page and on the alkaline list. A 120-gram roasted chicken breast comes to about +20.8. Add 200 grams of baked potatoes, skin on, at about −16.6 and 100 grams of raw spinach in a salad at −11.8, and the plate totals roughly −7.6. The chicken stays on the plate. The vegetables just take up more of it.
The same idea works at breakfast. Two hard-boiled eggs (+9) with a banana (about −8 for a medium one) and a cup of coffee is close to even. A cheddar sandwich on white bread comes to about +8.5 with 40 grams of cheese, but a 250-gram bowl of canned tomato soup (about −13) and a pear (about −3.7) bring the whole lunch back to roughly even.
Recipes that pair protein with plenty of vegetables
The lemon herb chickpea garden bowl uses near-neutral chickpeas with a large pile of greens and herbs, and it takes a few flakes of feta without tipping the balance. The roasted zucchini tahini grain bowl puts a small amount of grain under a lot of roasted vegetables. For a snack that replaces cheese and crackers, try the cucumber dill white bean dip with raw vegetables.
Where to read more
Our food-first approach to alkaline eating explains how this kitchen uses the word alkaline. To check a food that is not on either chart, the guide to looking up nutrition in USDA FoodData Central shows where to find the five nutrients the formula uses.
Frequently asked questions
Short answers to the questions we hear most about acid-forming foods.
What is the most acid-forming food?
Of the foods we calculated, hard parmesan scores highest, at about +24.7 per 100 grams. Swiss cheese, egg yolk, cheddar and roasted chicken breast come next. Portion size changes the picture: a 5-gram spoonful of grated parmesan adds only about +1.2.
Is coffee acid-forming?
No. Brewed coffee comes out at about −1.0 per 100 grams, which is slightly base-forming, because it carries potassium and almost no protein. It is mildly acidic in the cup, at a pH of about 5, which is a separate measurement.
Are acid-forming foods unhealthy?
Not as a group. Fish, eggs, poultry, dairy and whole grains are part of the eating patterns recommended in the Dietary Guidelines for Americans. PRAL ranks only one property of a food. What matters for a meal is the total once the vegetables and fruit are counted.
Does eating acid-forming food change blood pH?
No. The body keeps blood pH in a narrow range, about 7.35 to 7.45, whatever you eat. Diet can change the pH of urine, which is what PRAL was tested against.
Medical disclaimer
Medical disclaimer: this page is general food education for home cooks. It does not give medical advice, diagnosis or treatment, and it does not claim that any food on this list changes blood pH or prevents, treats or cures any disease. On this site, alkaline and acid-forming are recipe labels. If you have kidney disease, or have been told to limit protein, phosphorus or potassium, follow your own clinician's or dietitian's advice before changing what you eat. Several foods at the alkaline end of the chart are high in potassium. Please also read the full disclaimer on this site.
Sources
Remer T, Manz F. Potential renal acid load of foods and its influence on urine pH. Journal of the American Dietetic Association. 1995;95(7):791–797 (source of the PRAL formula used in the chart). https://pubmed.ncbi.nlm.nih.gov/7797810/
U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy (protein, phosphorus, potassium, magnesium and calcium per 100 g for each food listed). https://fdc.nal.usda.gov/
Reddy A, Norris DF, Momeni SS, Waldo B, Ruby JD. The pH of beverages in the United States. Journal of the American Dental Association. 2016;147(4):255–263. https://pmc.ncbi.nlm.nih.gov/articles/PMC4808596/
Schwalfenberg GK. The alkaline diet: is there evidence that an alkaline pH diet benefits health? Journal of Environmental and Public Health. 2012 (blood pH range and the diet-urine link). https://pmc.ncbi.nlm.nih.gov/articles/PMC3195546/
Fenton TR, Tough SC, Lyon AW, Eliasziw M, Hanley DA. Causal assessment of dietary acid load and bone disease: a systematic review and meta-analysis applying Hill's epidemiologic criteria for causality. Nutrition Journal. 2011;10:41. https://pubmed.ncbi.nlm.nih.gov/21529374/
U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025 (healthy eating patterns that include protein foods and dairy). https://www.dietaryguidelines.gov/
A thoughtful note: This article is for general education and inspiration. It does not provide medical advice, diagnosis, or treatment. Please see our full disclaimer.