Post title: "Can too much protein cause kidney stones?" over image of salmon, eggs, nuts and other food sources of protein

Can Too Much Protein Cause Kidney Stones?

Did your urologist tell you to follow a low protein diet? Or, perhaps you’ve read that protein is related to kidney stones. This is true! In susceptible people, too much protein can cause kidney stones.

Read on to learn more about how protein can cause kidney stones. And, what you can do about it!

What Is Protein?

Protein is an essential nutrient found in many different kinds of foods. Protein is made of amino acids, which are necessary for your body to function properly.

Protein is found in high amounts in foods like:

  • Beef, pork & other red meats
  • Poultry
  • Fish & Shellfish
  • Tofu
  • Beans, Nuts & Seeds
  • Dairy

One 3 ounce cooked portion of beef, chicken or fish has about 20 grams of protein. A 1/2 cup of beans has about 8 grams.

Protein is also found in vegetables and whole grains in smaller amounts. For example, 1 cup of raw broccoli has about 2 grams of protein. One slice of whole grain bread has about 4 grams.

How Does Too Much Protein Cause Kidney Stones?

Too Much Acid in Urine

Protein, especially from non-dairy animal foods like beef, chicken and fish, produce acid in your body during metabolism. Your kidneys get rid of extra acid in your urine. So, when you eat more protein, your urine will be more acidic. (1)

Acidic urine (or, urine with a low pH) is the biggest risk factor for uric acid stones. (2) Low urine pH may also make calcium oxalate stones more likely.

Fruits and vegetables produce alkali to help neutralize acid. (1) It is a balancing act. Your body absolutely needs some protein to function. But, it is important to eat plenty of fruits and vegetables to help balance acid produced from the protein you eat.

Potential Renal Acid Load (PRAL) is a common way to measure how much acid or alkali a food produces. Dietary patterns with a higher acid load are associated with kidney stones. (3) Learn more about PRAL and kidney health.

Bottom line: Too much non-dairy animal protein, especially without also eating plenty of fruits and vegetables, can increase urine acid and increase the risk of kidney stones in some people.

Lower Citrate in Urine

Eating too much protein can cause kidney stones by lowering urine citrate levels. (2)

Citrate is a powerful inhibitor of calcium kidney stones. It binds with calcium in urine, rendering that calcium unable to bind with other minerals to make a kidney stone. In fact, potassium citrate is a common medication prescribed to people with kidney stones. Potassium citrate can also be found in food.

Citrate is a source of alkali, and helps neutralize acid produced from protein in your diet. When you eat too much protein, extra acid is produced in your liver. To help neutralize that acid, your kidneys keep more citrate in your body, instead of getting rid of that citrate in urine. For kidney stone prevention, we want that citrate to end up in your urine so it can help prevent kidney stones.

Indeed, we see lower urine citrate amounts in people who eat more non-dairy animal protein. (4) (5)

Title: How Non Dairy Animal Protein Causes Kidney Stones with images depicting each factor: lower urine citrate, lower urine pH, possible higher urine oxalate and higher urine calcium

Possible Higher Urine Oxalate

Even though animal protein foods do not have oxalate in them, they may increase urine oxalate levels. (6)

Your liver can make oxalate from protein. When you eat too much protein, your liver may be more likely to make oxalate. (7) That oxalate is eventually excreted in your urine, and is one possible reason why high protein diets are associated with kidney stones.

Liver production of oxalate is significant. It accounts for nearly 50% of urine oxalate. (7) This is one of the many reasons it is so important to look at all of the foods you eat for kidney stone prevention, not just those high in oxalate. A focus solely on a low oxalate diet is negligent and potentially dangerous. It restricts many foods shown to be beneficial for health and completely disregards the complex nature of oxalate balance and kidney stone formation.

Higher Urine Calcium

Lastly, too much protein can cause kidney stones by increasing urine calcium. (8) (9) High urine calcium is one of the most common causes of kidney stones.

Note: High urine calcium does NOT mean you need a low calcium diet. In fact, a low calcium diet can make calcium kidney stones worse. (10) The relationship between kidney stones, urine calcium and dietary calcium is much more complex. Learn more about calcium and kidney stones.

Type of Protein & Kidney Stones

Protein is not created equal when it comes to kidney stone prevention. Usually, non-dairy animal protein is the culprit if protein is a concern for kidney stones.

Why so specific? Let’s break it down.

Non-Dairy Animal Protein & Kidney Stones

Non-dairy animal protein is specifically called out in the American Urological Association’s recommendations for kidney stones.

This is because animal protein produces more acid compared to protein from plant foods or dairy. (11) Non-dairy animal protein changes urine chemistry in ways that are generally negative for kidney stones such as higher acid and less citrate.

Sources of non-dairy animal protein are:

  • Beef, pork & other red meats
  • Poultry
  • Fish & Seafood
  • Eggs
  • Game Meats
  • Organ Meats

Dairy Protein & Kidney Stones

Dairy is an important source of calcium for people with calcium kidney stones. Eating enough calcium is critical for people with calcium oxalate kidney stones. Dietary calcium binds oxalate in the intestine, causing that oxalate to be excreted in stool, rather than getting absorbed and excreted in urine. (2)

People with kidney stones should aim for 1,000-1,200mg calcium from food per day. (2) (12)

Dairy does not produce the same amount of acid as other animal protein foods. In general, milk and yogurt are neutral in terms of acid load. Most cheese produces a small amount of acid. (11)

Most importantly, diets high in dairy are consistently linked with lower kidney stones. (13)

For these reasons, dairy protein is typically not restricted for kidney stones.

Plant Protein & Kidney Stones

Plant protein is a very good thing for kidney stones! Plant protein foods do not produce acid, so will not change urine chemistry negatively like non-dairy animal protein foods can. In fact, diets that include plenty of plant protein foods, like the Dietary Approaches to Stop Hypertension (DASH) and the Mediterranean Diet, are associated with fewer kidney stones. (14) (15)

Plant protein foods are:

  • Beans
  • Nuts
  • Seeds
  • Lentils
  • Tofu
  • Peas

Concerned about the oxalate content in these foods? Make sure you really need to follow a low oxalate diet (not everyone with calcium oxalate stones does!). Also, there are many lower oxalate beans and nuts & seeds!

Frequently Asked Questions

How Much Protein Can I Eat with Kidney Stones?

The amount of protein that is right for you depends on your body size, past medical history, lifestyle and kidney stone risk factors.

If your 24-hour urine test reveals that limiting protein could help prevent kidney stones, a good rule of thumb is to aim for 0.8-1.0 grams of protein per kilogram body weight per day.

For example, a person who weighs 175 pounds (79.5 kilograms) needs about 64-80 grams of protein per day.

This protein recommendation includes protein from all food sources. But, the focus should really be on reducing non-dairy animal protein. It can be helpful to focus on replacing non-dairy animal foods with more plant protein and dairy.

A Registered Dietitian is the best person to help you figure out how much and what type of protein is right for you. You may need more or less protein than the general recommendation.

Does Protein Powder Cause Kidney Stones?

Protein powder can cause kidney stones in susceptible people. As most people are already eating more protein than they need, extra protein from protein powder could easily bring your daily protein total above recommended levels. (16)

Protein adds up quickly. Most protein powder has about 20 grams of protein per scoop. In our above example, this is 27% of protein needed in an entire day. Added to protein from food you eat, protein powder can easily send you way above your daily protein goal. A small 3 ounce portion of chicken has about 20 grams of protein.

Protein powder can also have added sugar and sodium. These things can increase kidney stone risk further.

Does Whey Protein Cause Kidney Stones?

Whey protein powder could also cause kidney stones. Although whey protein is derived from dairy (cheese, to be specific!), it does not have as much calcium as dairy. So, it will not provide the same benefits for kidney stone prevention. Whey protein powder will likely be acid-producing due to its very high protein content, and relatively small amount of potassium, calcium and magnesium.

Just like protein powder in general, whey protein could cause kidney stones by adding excess protein to your diet.

Can Collagen Cause Kidney Stones?

Just like protein powder in general, collagen peptides could cause kidney stones. If collagen protein powder adds excess protein to your diet, it could increase kidney stone risk.

Can I Still Eat Meat?

Yes! A kidney stone diagnosis does not mean you have to be vegetarian. Although, eating a more plant forward diet can be hugely helpful for kidney stone prevention. (13)

If your 24-hour urine test reveals excess protein is a cause of kidney stones, the key is to eat the right amount of protein. If you enjoy meat, poultry, fish or seafood, you can absolutely eat them and still prevent kidney stones. You may just have to eat them in smaller portions, or eat them fewer times per day.

A Registered Dietitian can help you figure out how much meat is right for you!

How Do I Prevent Kidney Stones?

Protein is only a small piece of the puzzle for kidney stone prevention. For effective prevention, kidney stone nutrition must be personalized to your 24-hour urine test results. There is no one-size-fits-all “kidney stone diet”.

Learn more about calcium oxalate and uric acid kidney stones.

Can You Help Me? I’m confused.

Absolutely! Kidney stone nutrition is anything but straightforward. It is different for every single person, depending on your 24-hour urine test results. You do not have to do this alone.

I help people prevent kidney stones and feel confident in their food choices in Kidney Stone Nutrition School!

Happy Eating!

Melanie

21 thoughts on “Can Too Much Protein Cause Kidney Stones?”

  1. Hi Melanie; Thanks for all your great work.

    I’m curious what are your thoughts on the possible effects of Vegan Meat Substitutes?

    kind regards

    Shane

    1. Melanie Betz MS, RD, CSR, CSG

      I don’t love them as a general rule. They tend to be just as high in protein as actual meat, and PACKED with sodium. Obviously I firmly believe that all foods can be included in a healthy dietary pattern, but these aren’t something I recommend people work to include in their meals!

    1. Melanie Betz MS, RD, CSR, CSG

      Good question! Honestly, I would treat them the same way as normal protein powders. They really don’t have the benefits of actually EATING plant protein, so would put them in the same category as non-vegan protein powders.

  2. I’m mostly plant based, but find it almost impossible to get 60 grams of protein or 1200 calcium on a vegan type diet. That’s a lot of beans, broccoli and plant milk. I recently started adding plain Greek yogurt and a little salmon each week, but still hard without loading up on beans and tofu beyond a normal 1/2 cup portion (and without overloading on oxalates). What would one consume daily to get to calcium or protein requirements without consuming meat or saturated fat?

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Diana! That is wonderful to hear. A plant based diet is a great thing for stones. You might be reaching that 60 grams of protein without realizing it. Remember, there is a little bit of protein in nearly everything you eat (except fruit, which tends to be very low). Even veggies have a little! I’d love to help you learn more and make sure your diet is well balanced and ideal for stone prevention for you! Have you considered joining Kidney Stone Nutrition School?

  3. Hi Melanie,
    I have a question that has nothing to do with your post here, because I’m having trouble finding the answer anywhere else and this just came into my inbox; hope you don’t mind.

    I’m trying to find the oxalate content in Jackfruit, or at least find out where it ranks. Is it low, medium or high?

    I hope you will answer my question here, or tell me where I can find out.

    Thank you!
    Denise

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Denise! I unfortunately don’t have an accurate oxalate content for jackfruit handy. Sorry, I wish I could help!

      1. Thank you anyway Melanie. I’ve never had jackfruit and my husband wants to try it. Seems nobody has an answer. Guess I’ll just have more dairy with it!

        God bless.

        1. Melanie Betz MS, RD, CSR, CSG

          Wish I could be more helpful! Since I don’t advocate for a super low oxalate diet for nearly anyone anyway, I think your plan sounds good!

  4. It’s me again 🙂 You note that “most cheese produces a small acid load”, but that would seem to be at odds with a chart in one of the linked-to studies (https://www.sciencedirect.com/science/article/pii/S1548559512002091) that states that hard (and processed) cheeses in particular produce the highest acid load of all, with only soft cheeses having a small acid load. Where do common cheeses like cheddar, swiss, gouda, etc. fall – are they considered to be hard or soft? Also, it seems we should all be eating a ton of raisins since they have the lowest PRAL of all foods listed in the chart! [ PS – I’ve asked this before and don’t remember the answer: it would be great if a poster could get an email acknowledgement and link to a post once it has been approved and also in case of any reply or further activity in the thread. As it stands now, I have to keep updating this page to see any changes or activity! ]

    1. Melanie Betz MS, RD, CSR, CSG

      According to my calculations, most “regular” cheeses like cheddar have a PRAL of 2-4mEq of acid (or so). This, compared to animal flesh proteins, which produce about 15mEq of acid. I really encourage people to avoid getting into the nitty gritty of how much acid each food individually produces. Afterall, it is the entire dietary pattern that will make a difference!

      I’ll try to play around with the settings so people get a notification when I respond to their comment!

      1. Then that differs markedly from the colorful chart in the Science Direct link, which puts hard cheeses (whatever those are) at 30 mEq and soft cheeses at 10 mEq. Granted though, the study is 10 years old now. I’m sure this will mean more to you than to me, but the caption on the chart says “Figure 1. Estimated acid-producing potential of selected foods. Potential renal acid load (PRAL) of selected food items (per 100-g serving) is adapted from estimates performed by Remer22 and calculated as PRAL (mEq/d) = 0.49 × protein (g/d) + 0.037 × P (mg/d) − 0.021 × K (mg/d) − 0.026 × Mg (mg/d) − 0.013 × Ca (mg/d).”

        1. Melanie Betz MS, RD, CSR, CSG

          Yes. I see that. The exact acid load value will vary quite a bit depending on the exact way you calculate it, and the nutrition information you get for each specific type of cheese. This is one of the many reasons I avoid using this dietary acid load concept this granularly. There is not a “target” value we should be aiming for in each food or even for the day. Instead, it is a concept to think about whole dietary patterns and helps explain why some are so beneficial to kidney health.

  5. I was a vegetarian for most of my adult life, eating a zero animal protein diet in the interest of health and longevity, and suffered from calcium oxalate kidney stones. Since forgoing the vegetarianism and adopting a high animal protein/high fat diet I have had no incidence of kidney stones. I’m not saying I won’t in the future, but it’s been years without one now. I still keep a low oxalate diet despite having low oxalate levels last time I had a 24 hour urine test. What I’m doing seems to be working and I’ll stick with it until something in my body tells me I need to change it. Everyone’s physiology is so different, generalized nutrition advice is risky at best. Nonetheless, I love the site and I will continue to follow for updates and information.

    Thank you!

  6. https://kidneystones.uchicago.edu/ — here’s an excerpt from Dr Coe’s main page.
    I was trying to limit protein and on my last 24-hr urine test, I actually was below range on protein.
    Aren’t eggs fine, too, in addition to dairy?

    Thanks

    Diet Protein and Potassium and Stones
    Red meat has a bad rep it may not deserve. For example, it does not promote kidney stones. You would think it might. Protein can raise urine calcium excretion and that is a major stone risk. But over the range of intakes we encounter in normal life, between 0.8 and 1.2 gm/kg/day of protein, risk does not rise. I presume body builders who snack on protein bars and protein powders may raise their stone risk, but the data we have does not support that – even so, it is probably not a great idea. On the other side of the diet divide, veggies lower stone risk, a lot. Part of the reason is they have a lot of potassium citrate and other alkaline potassium salts. Part, they have a high water content so urine volume goes up. Eat your red meat – not a problem for stones. Eat your veggies, a real benefit. Did I mention dairy protein? No risk, maybe a little protective. The article has been updated from its original, and I made a video for it. You can watch the video or read the article, or both. Incidentally, I did the video because someone wrote in and asked me to. I told her I would do it, and here it is.

    1. Melanie Betz MS, RD, CSR, CSG

      Eggs actually function a bit more like animal flesh protein than dairy. But, are definitely somewhere in the middle. And yes – my recommendations are in line with with Dr. Coe discusses in that article. The issue comes about when people eat EXCESS non-dairy animal protein!

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top