What Is PRAL & How Does It Affect Kidneys?

If you’ve ever wondered about the impact of food on body acid levels, this article is for you! PRAL is a measurement of the acid (or alkaline) produced from your diet in your body. People with kidney disease, and some other chronic conditions (including kidney stones!) can make changes to their diet to reduce PRAL, or dietary acid, to help improve health.

PRAL is anything but straightforward, so let’s start at the beginning.

What is PRAL?

“PRAL” stands for Potential Renal Acid Load.  PRAL is a measurement of the amount of acid, or base (aka “alkali”) your diet produces in your body.  Higher PRAL values indicate more acid is produced from your food.  Negative PRAL values indicate that base (the opposite of acid) is produced. 

The total PRAL of your diet is the balance of the acid and base produced by your diet throughout the day. PRAL is measured in milliequivalents of acid per day. (1)

The pH in your body is the amount of acid relative to the amount of base.  Your body is constantly striving to keep pH at healthy levels, and is tightly regulated by your lungs and kidneys.  Acid is produced in our bodies from normal processes such as digestion and metabolism.  Your body relies primarily on the kidneys to get rid of extra acid your diet generates. Your lungs help a little too!

PRAL is becoming more and more common in nutrition research. More dietitians and doctors are beginning to recommend eating based on the principle of PRAL.  Keep reading to learn more!

PRAL Calculation

PRAL is calculated from 5 nutrients that create either acid or base in our bodies.  Protein and phosphorus create acid during metabolism; whereas potassium, magnesium and calcium produce base.  By far, protein is the biggest determinant of PRAL. The more protein a food has, the higher the PRAL value. (1)

Nutrients impact on PRAL

PRAL and Food

PRAL is best used for evaluating an entire diet, not just a single food.  However, for the sake of education, I think it is useful to compare the PRAL for single foods to understand the benefit of eating more (or less!) of those foods.

To reduce the acid load on our kidneys, our goal is to reduce the amount of protein in our diet (acid producing), and increase the amount of foods that produce alkali or base.  What does this mean for our actual meals?

Take a look at this chart. Notice that most animal proteins such as beef and chicken have a very high PRAL value.  This is because most animal proteins have a lot of protein and phosphorus, and are relatively low in potassium, magnesium and calcium.  Most plant proteins (such as lentils, beans and nuts) have a negative PRAL value, representing that these foods produce base in our body.  In addition, most fruits and vegetables have a negative PRAL.

PRAL for Individual Foods

 Portion SizePotential Renal Acid Load (PRAL, mEq/day)
Proteins
Beef Steak4oz, cooked12.9
Chicken4oz, cooked16.3
Cod4oz, cooked13.5
Shrimp4oz, cooked14.5
Black Beans½ cup, cooked-2.6
Lentils½ cup, cooked-1.5
Walnuts¼ cup1.7
Egg1 whole3.7
Grains
Whole Grain Bread1 slice1.8
White Bread1 slice0.8
Brown Rice½ cup, cooked2.2
Quinoa½ cup, cooked2.1
Dairy
2% milk1 cup-1.5
Low Fat Plain Yogurt1 cup0.4
Cheddar Cheese1 slice3.5
Fresh Mozzarella Cheese1 slice3.8
Fats
Olive Oil1 tablespoon0.0
Unsalted Butter1 tablespoon0.1
Vegetables
Broccoli1 cup, cooked-5.5
Green Beans1 cup, cooked-3.5
Tomatoes½ cup, chopped-3.7
Carrots1 cup, cooked-6.4
Fruits
Banana1 medium, raw-8.2
Peaches1 medium, raw-4.7
Blueberries1 cup, raw-1.5
Pineapple1 cup, cubes-3.6

PRAL Food Chart

To make this a little easier, I classified foods into what group they generally fall into.  Our goal is balance the higher PRAL foods we eat, with enough negative PRAL foods.

PRAL Food Table

High PRAL Foods (Acid Producing)Overall Neutral PRAL FoodsNegative PRAL Foods (Base Producing)
BeefFats & OilsAll fruits
PorkAll vegetables
LambBeans
Chicken & TurkeyLegumes
Fish & SeafoodMilk & Yogurt
**Moderately acid producing foods**
Grains
Eggs
Cheese
Images of base producing (negative PRAL) vs. acid producing (high PRAL) foods. Negative PRAL foods include tomatoes, grapes, broccoli, peppers, peaches and most plant proteins. High PRAL foods include poultry, beef, pork, lamb, fish and seafood.

Side Note: High PRAL Foods vs. Acidic Foods

High PRAL foods are not necessarily foods that are acidic.  This can be confusing and is an important difference.   High PRAL foods are usually not acidic before we eat them.  For example, tomatoes and pineapple are acidic, but they have a negative PRAL value.  This is because the acid in food is very different than the acid PRAL measures.  The acid in food is neutralized by hydrochloric acid in our stomach and does not increase the amount of acid in our bodies.  PRAL measures the acidity of food’s metabolites, not the food itself.

People with heartburn or gastroesophageal reflux (GERD) may find relief from avoiding acidic foods such as tomatoes, orange juice, pineapple or vinegar.  Of course, if you suffer from this condition and avoiding these foods helps your symptoms, by all means, avoid these foods!  However, if you tolerate these foods just fine, there is absolutely no reason to avoid acidic foods.

Diet Patterns and PRAL

Of course, none of us live off only one food.  What a terribly boring life that would be! Because we eat a variety of foods, it is most important to consider PRAL for your entire diet. The goal is not to demonize all high PRAL foods and elevate only negative PRAL foods.

Reducing the PRAL of your diet really boils down to three important points:

  1. Eat more foods that produce base. This will help neutralize acid from the protein that you do eat. Your body does need some protein! This means eating large amounts of vegetables and fruits.  Yet another reason fruits and veggies are good for us!
  2. Eat the right kind of protein. Plant proteins like beans, lentils and nuts create much less acid in our bodies compared to meat, poultry and fish. Many plant proteins even produce base!  Swapping out meat for plant-based proteins, even for just 1 meal per day, can help reduce the PRAL of your diet.
  3. Eat the right amount of protein. No matter what kind of protein you are eating, if you eat a very high protein diet, it will have a high PRAL value. It is important to work with a Registered Dietitian to understand how much protein is right for you.

Popular Diet Patterns and PRAL

A couple popular dietary patterns fall into these three recommendations to reduce PRAL nicely. 

The Dietary Approaches to Stop Hypertension (DASH) diet focuses on eating at least 10 servings of fruits and vegetables per day.  In addition, the DASH diet recommends 3 servings of dairy with a focus on incorporating plant-based proteins. Dietary patterns consistent with DASH would have a low PRAL value.  In addition, DASH as been shown to be incredibly effective at lowering blood pressure! (2)

Check out more info about the DASH diet, or download this handout.

The Mediterranean Diet is another popular, well-researched, dietary pattern that has a low PRAL value.  The Mediterranean diet is most known for its benefit on heart health. (3)  It has also shown benefit in reducing risk for Alzheimer’s, dementia and cognitive decline in old age. (4) (5)

Read more about the Mediterranean diet.

Who Should Follow a Low PRAL Diet?

A low PRAL diet will always be high in fruits & veggies, keep meat portions reasonable, and will likely include more plant proteins.  Honestly, these dietary changes are probably good practice for almost everyone!

There are some specific health conditions a lower PRAL diet has been shown to be helpful.

Chronic Kidney Disease (CKD)

A low PRAL diet is probably most known for it’s benefits for chronic kidney disease. Dietary patterns lower in PRAL can help control acidosis and have been shown to slow the progression of kidney disease.

To understand how PRAL can impact kidney disease, let’s understand a little more about acid, food and your kidneys.

Acid and Kidney Disease

Your diet is the biggest factor that determines how much acid your kidneys have to deal with. (6)  For most people, your kidneys get rid of this extra acid and it does not cause any problems.

In kidney disease, kidneys cannot get rid of extra acid as well as they should.  This causes acid to build up in your blood. This is called “acidosis”, and has many negative health effects.

Acidosis is very common in people with kidney disease.  An estimated 13% of people with CKD stage 3 have acidosis, and this increases to almost 40% by CKD stage 4. (7)  Even people with earlier stages of kidney disease (CKD stages 1 and stage 2) keep more acid in their bodies compared to people without kidney disease. (8) Your doctor will frequently check how much carbon dioxide (CO2) is in your blood.  C02 is a measurement of how acidic your body is.  Most doctors want your C02 level to be 22 mEq/L or higher5. (9)

Consequences of Acidosis

  • Weak bones and osteoporosis
  • Faster progression of kidney disease
  • Muscle loss
  • Possible worsening of heart disease and inflammation
  • Taste changes
  • Poor appetite
  • Fatigue
  • Headache (10)

Treatment for Acidosis

Acidosis in kidney disease is usually treated with a medication called sodium bicarbonate. (10)  This medication gives you a large dose of base, which helps neutralize extra acid in your body.  Potassium citrate is another common medication to treat acidosis.  However, potassium citrate is not used as much for people with kidney disease because of the large amount of potassium in it.

I know all this acid talk can sound sort of scary.  But, I have good news! What you eat directly impacts how much acid you have in your body.  In fact, some foods can actually help get rid of extra acid.  You can use diet to help treat acidosis! This is where PRAL comes in.

Eating a diet lower in PRAL can help prevent and treat acidosis for people with kidney disease. In fact, fruits and veggies have been found to be almost as effective as sodium bicarbonate in preventing acidosis! (11) (12)

Potassium, PRAL & Kidney Disease

Some people with advanced kidney disease need to limit how much potassium they eat.  If you fall into this category, some fruits and vegetables are not the best choice for you, even though they have a low PRAL. 

However, acidosis can make high blood potassium levels worse. So, eating as many low PRAL fruits and vegetables as possible might actually help potassium levels in the end by improving acidosis, even though they technically have more potassium. (13) Always ask your Registered Dietitian what is best for you.

More about potassium and kidney disease. 

Kidney Stones

Lower PRAL dietary patterns may also help prevent certain types of kidney stones. (14) (15)

The PRAL of your diet directly impacts the pH of your urine. Your body’s main way of getting rid of extra acid is via urine. So, the more acid you eat, the more acid ends up in your urine, which lowers your urine pH.

How Does PRAL Impact Kidney Stones?

Urine that is too acidic (or, has a low pH), makes it easier for both uric acid and calcium oxalate kidney stones to form. This is especially true for uric acid kidney stones. Low urine pH is the biggest driver of uric acid kidney stones. (16)

So, eating a lower PRAL diet can help reduce urine acid, and prevent these types of kidney stones.

A lower PRAL diet can also help increase urine citrate. Citrate is a powerful inhibitor of kidney stones, so higher levels of urine citrate is a good thing for kidney stone prevention. (17)

Low PRAL Food Patterns & Kidney Stones

The connection between PRAL and kidney stones goes beyond this very “sciency” explanation. We see this science and biochemistry play out in real life!

People who eat lower PRAL diets have about a 50% reduced risk of kidney stones. (14) (15) In addition, dietary patterns that would inherently have a lower PRAL such as the Dietary Approaches to Stop Hypertension (DASH) and a Mediterranean diet have also been associated with a lower risk of kidney stones. (18) (19)

Kidney stone nutrition is very different for every single person, depending on their 24-hour urine test results. Kidney Stone Nutrition School will help you come up with a personalized kidney stone prevention plan.

Other Health Conditions

Although most of the research about the health benefits of PRAL are around kidney health, a lower PRAL diet may be helpful for many other chronic conditions.

PRAL has been associated with improvements in diabetes & insulin resistance, heart disease and bone health. (20) (21) (22) (23)

Combating a High PRAL Diet with Supplements?

A Google search will reveal endless supplements and food products claiming to reduce acid in your body and cure all ailments from anxiety to diabetes.  Most of this is completely unsupported by research and I generally do not recommend them.

Some of these products, such as alkaline water, have not been shown to be effective to improve health. It is difficult to know if alkaline water and other supplements are just alkaline themselves, or if they actually produce alkali during metabolism. The production of alkali is what we are really after.

Even if these products do produce alkali, getting alkali (or base) from specialized foods or supplements robs you of the benefit of getting alkali from fruits and vegetables. Fruits and vegetables have countless benefits other than just alkali. 

In addition, as with any dietary supplement, there is a danger of getting too much alkali.  It would be almost impossible to get too much alkali from food as your body has all sorts of checks and balances in place to regulate reasonable doses of acid and alkali from food.

Happy Eating!

Melanie

35 thoughts on “What Is PRAL & How Does It Affect Kidneys?”

  1. Thank you for a great explanation…I am now getting it…
    What would the PRAL #. be if one wanted to calculate 20 % of acid based on a 2,000 calories day …more or less

    1. Melanie Betz MS, RD, CSR, CSG

      PRAL isn’t dependent on calories. There isn’t really a “goal” PRAL to target – it is more of a general concept and a possible explanation why eating more plants tends to be good for both kidney disease and kidney stones!

  2. Thank you for the great article. It discusses blood alkaline levels but can you tell me what, if any, relevance urine alkaline level has in kidney or general health.
    Thank you!

    1. Melanie Betz MS, RD, CSR, CSG

      Yep! Urine pH plays a big role in kidney stone formation. I discuss this in this article under the kidney stone section!

  3. Could you tell me if whey protein or collagen protein also have the same high acid content as chicken or beef (for the same proportionate amount of protein)?
    Thanks!

  4. Hi, can you please tell me where nutritional yeast flakes (for example, the KAL brand) are on the PRAL scale? I believe they are grown on molasses.
    Thanks!

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Rachel! Without doing a formal calculation, my guess is they would be relatively low PRAL or neutral given the fact that they are not an animal based source of protein. But, definitely ask your dietitian what is best for you to eat!

  5. Where does nutritional yeast flakes (KAL brand, for example) fall on the PRAL scale? I believe this product is grown on molasses. A lot of vegetarians use this as a protein supplement.

    Thank you so kindly.

  6. Hi, can you please speak to osteoporosis and the PRAL diet? I have oatmeal, sourdough bread, peanut butter, fish most days and fruits and vegetables and sometimes a dairy serving or bowl of cornflakes. I’ve been lacto-ovo-pesca vegetarian for almost 40 years but now have a diagnosis of osteoporosis. I love soy products but for a while I didn’t feel good when I ate them, hard to describe it but maybe it affected my thyroid in some way. Now considering going to unsweetened soy milk for more protein with the idea of dropping the seafood in favor of something more alkaline than fish. Can you please guide me to a more comprehensive PRAL list? Thank you kindly.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Becky! There is some research to suggest that a more alkaline producing dietary pattern could be beneficial for bone health – as the calcium stores in your bones are the biggest buffer your body has to neutralize acid produced from your diet. I don’t advocate looking at PRAL lists – instead it is all about generally eating more produce (ALL produce base) and fewer animal proteins (ALL produce acid) will help reduce the acid load of your diet. I highly discourage eating or avoiding specific fruits or veggies because they are high/low PRAL – variety is SO much more important!

  7. I am confused about using acids like lemon juice to prevent more oxalate kidney stones which is what my husband was told to do to no avail. Despite cutting back on chicken, beef and fish, taking potassium citrate and adding one half a cup of lemon juice to his daily water quota, this week he is having his 6th surgery, this time to repair damage from oxalate stone removal. If the lemon juice is acidic, it seems to me to be counterintuitive to add it to your diet to prevent kidney stones. It is better to not add lemon juice to the diet? Thanks

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Carol! Lemon juice is sometimes recommended to prevent kidney stones due to the citrate content. IF your urine citrate is low on a 24 hour urine test, then this could help prevent stones. If it is not low, that lemon juice likely wont do much. On the acid front, you have to consider what acid/base a food is AFTER metabolism. The acid level of a food when you eat it doesn’t really matter (see tomato and pineapple examples in this article). Even though these foods themselves are acidic, they produce base during metabolism. I can’t say what is best for your husband without working with him and reviewing his urine test results and medical history. If you would like my help learning more about what he can do to prevent stones, please check out Kidney Stone Nutrition School!

  8. My husband has just been diagnosed with lymph and the chemo has damaged his hey and kidneys. He has a gfr below 22 his creatinine is 261 and high urea. Drs say there is nothing we can do to save his kidney function as he is now below 22% function. Can you suggest what foods he must eat to improve his kidney function or at best what he must avoid in order to halt further damage. Prior to lymphoma diagnosis he was diagnosed with diabetes 2 over 40 yrs ago and has managed it with diet alone up until 2012 when he was required to go on meds when he was diagnosed with left ventricular non compaction cardiomyopathy. I would appreciate any advice. Thank you.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Rose! I’m very sorry to hear about your husband. But I am so happy you and he are motivated to make nutrition changes to help his kidneys! There are not specific foods he can eat to improve function – nutrition is all about learning how to put together whole dietary PATTERNS. Nutrition for kidneys is also very different for each person depending on their labs, medical history and some other factors. I’d recommend he meet with a dietitian individually to learn specifics for him.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Betsy! The goal of targeting renal acid load is really not to “track” or “count” it. Goodness knows that LAST thing we need is more numbers to track on a kidney friendly diet! Truly, there isn’t an ideal “target” PRAL anyway. Instead, this is a general concept and a likely reason why we see such better kidney health outcomes in people who generally eat more plant foods!

  9. I really hope you will do a full list like you did for oxalate. Especially corrected for serving size. I looked online for other foods, and only found results for 100g and 100 calorie servings.
    Was really surprised to find corn is a positive and goat’s milk is a negative.

  10. Good day Melanie,

    I am a 68 yr old male with a eGFR of 47 and a eGFR BLACK of 55. Can you tell me the difference between the two numbers please?

    Thanks Fred

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Fred! Great question. These 2 GFR numbers are simply calculated with different equations. However, there is a push that just started last year to NOT use the African American eGFR equation as it contributes to racial healthcare disparities for people with CKD. Here is a really good summary of the issue from the National Kidney Foundation!

  11. Mary Jane Plemons

    Melanie, when dried beans are used as a main dish, my husband wants about one-and-a-half to two cups of beans with a piece or two of cornbread. He likes large limas or pinto beans. Because of the potassium and phosphorus, we seldom have beans and cornbread. He has a GFR of 8, not on dialysis, and still feels well at age 83. His CO2 is usually 21 to 22, checked every two months, but his phosphorus is usually 5.4 to 5.5. He takes two sodium bicarb tablets, twice a day and Sevalamer, two tablets three times a day. This whole PRAL idea is new to me, and I’m not sure how to proceed with meal planning. Would you recommend the beans and cornbread continue as a only rare treat? His doctor wants his potassium intake at no more than 1500 mg. per day, and we have succeeded in bringing the lab values down to 5.1 to 5.2. Thank you for any light you can shed.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Mary Jane! Honestly, I’d much prefer he eat beans & cornbread over any animal protein based dish. So, if done correctly, I think beans could be incorporated every day! The key is using beans IN PLACE of meat at meals. There is a surprising amount of potassium in meat/chicken/fish (AND, these foods often have un-identifiable potassium additives as well!). So, beans don’t usually have that much more potassium in them compared to meat and other animal proteins. Because the phosphorus in beans is SO much less absorbed than the phosphorus in meat, phosphorus control is actually better. 2 cups of beans is quite a bit, for a whole meal, I’d usually recommend closer to 3/4-1 cup. Of course, everyone is different, so pass any changes you make past your dietitian!

        1. Mary Jane Plemons

          I should have also said, we only eat two meals a day, a big breakfast and then early supper. As a rule, we don’t eat snacks. When we have beans and cornbread, we don’t usually have anything with them, except maybe a salad sometimes.

          1. Melanie Betz MS, RD, CSR, CSG

            Then the larger portion size might make sense! I obviously have no idea how many calories your husband needs without knowing more about his history. Yay for beans!

  12. I came across your post while searching for studies on PRAL, since I noticed that mine is consistently in the negative range according to Cronometer – for instance, yesterday was minus 84.

    You are spot on about animal protein. I have been a vegetarian for a long time and whole foods vegan for the last few years, and my doctor comments at how high my eGFR is, especially for someone who is 60.

    Now PRAl and my negative numbers make more sense to me. Thanks!

  13. Hi Melanie, thank you your site is excellent, I’m learning so much. Do you know if black tea, green tea, rosemary tea, lemongrass and turmeric would be negative PRAL or acidic? I like to drink a lot of these teas.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Amanda! Thank you so much and you are so welcome! Tea would all be basically neutral in terms of dietary acid load.

  14. Just trying to get pral ratings straight. Your chart shows quinoa 2.1 while another chart shows it as
    quinoa -0.191 PRAL Value (mEq/day). Please let me know which is correct.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Norm! PRAL depends on exactly how much protein, phosphorus, calcium, potassium and magnesium is used to calculate it. Depending on the nutrition database used to find these nutrient amounts, this could change PRAL slightly. My guess is this accounts for the slight difference between my value and this other chart. Either way, that is a pretty much neutral PRAL value. Nutrition is not an exact science!

  15. Thank you! I am a 68 yr old female and have had acid reflux for 15 years. Not one doctor has mentioned PRAL. I also was surprised to see from your PRAL list that chicken was higher than beef ` yippee. This article was clear and right to the point. :)fran

    1. Melanie Betz MS, RD, CSR, CSG

      Thank you Fran! PRAL is a relatively new area of research, so it’s not surprising that your doctor didn’t bring it up. In general, any kind of animal flesh, whether it be chicken, beef, pork, fish, seafood, etc., is going to be about the same in terms of PRAL. However, it is important to remember that lean cuts of meat (i.e boneless chicken, fish, etc.) are still better for heart health!

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