Top 8 Reasons You Keep Getting Kidney Stones On A Low Oxalate Diet

You’ve been diligently following a low oxalate diet and you keep getting stones. How can this be? It is a terrible place to be in: thinking you are doing everything “right” and still getting stone after stone. There must be more to the puzzle.

Low oxalate diets are not necessarily the most effective way to prevent kidney stones. Healthy eating for kidney stones is about a lot more than oxalate. In fact, I don’t even give many of my patients an oxalate food list! Healthy eating for stone prevention must be based on your individual urine risk factors. A low oxalate diet is only necessary if one of your risk factors is high urine oxalate.

Here are the most common mistakes I see people make with low oxalate diets.

1. You Don’t Have Oxalate Kidney Stones

This happens all the time. Unfortunately, people are often told to follow a low oxalate diet without even knowing what kind of kidney stones they have. About 80% of kidney stones are calcium oxalate, so sometimes doctors assume kidney stones are calcium oxalate. However, there are many different kinds of kidney stones including phosphate, uric acid, struvite and cystine. A study found that emergency rooms often given inappropriate nutrition advice for kidney stones. (1)

If you do not have oxalate kidney stones, following a low oxalate diet is not going to prevent more kidney stones.

2. You Don’t Have High Urine Oxalate

Even people who have oxalate kidney stones do not necessarily need to follow a low oxalate diet. Oxalate kidney stones can be caused by a variety of things. In fact, high urine calcium is the most common cause of oxalate kidney stones, not high urine oxalate. (1) Urine citrate, pH and other factors also play a role.

If you don’t have high levels of oxalate in your urine, cutting back how much oxalate you eat isn’t going to make much difference. Only a 24-hour urine test will be able to tell you and your doctor if you have high urine oxalate.

More about who needs a low oxalate diet in the first place!

3. You Aren’t Drinking Enough Water

Drinking enough water is the most important part of kidney stone prevention. (1) No matter how healthy your diet is, if you are not drinking enough water, you may be at risk for kidney stones.

The American Urological Association recommends drinking enough fluid to make 2 1/2 liters of urine per day. (2) For most people, this means about 3 liters of fluid per day. Your goal might be more or less depending on your medical history and lifestyle factors. Ask your doctor or dietitian how much water is right for you.

Getting in this much water is no easy task! Many of my patients have found that using a smart water bottle, like the Hidrate Spark* to be incredibly helpful to meet their fluid goals!

HidrateSpark 3 -- The World's Smartest Water Bottle

4. You Aren’t Eating Enough Fruits & Vegetables

Some people overdo the oxalate restriction and cut out too many fruits and vegetables. Contradictory oxalate food lists and websites spreading false, alarmist information about oxalate can scare people away from eating ANY healthy fruits and veggies. However, fruits and vegetables are non-negotiable for kidney stone prevention.

In every single study I’ve ever read, people who eat more fruits and vegetables are less likely to form kidney stones. (3) Although most fruits and vegetables do have a least a little oxalate, they also have all sorts of good things in them that can help prevent kidney stones. Citrate, potassium, magnesium and alkali are examples.(1) They are also a critical piece of a balanced meal. Without them, meals are usually too high in either protein or carbohydrate, which could contribute to stones as well.

A strict low oxalate diet of 50mg or less per day makes it very difficult to eat a variety of nutritious foods. And, may be doing more harm than good. For most people, simply avoiding foods very high in oxalate, along with eating enough calcium, is enough to bring urine oxalate down to safe levels.

Foods Very High in Oxalate

  • Spinach
  • Almonds & almond products
  • Beets
  • Rhubarb
  • Raspberries
  • Navy Beans
  • Miso

If taking these foods out of your diet doesn’t lower urine oxalate, I usually recommend 100mg of oxalate per day. However, your diet should be individualized to your 24-hour urine results.

5. You Aren’t Eating Enough Calcium

In a landmark study, people who ate enough calcium had a 50% reduced risk of kidney stones compared to people who limited calcium – both groups were following a low oxalate diet. (4)

Calcium is so important because it binds to oxalate in the intestine and reduces oxalate absorption. Eating enough calcium is a very effective way to reduce urine oxalate.

More about calcium and kidney stones.

6. You Aren’t Paying Attention To What You DO Eat

Healthy eating is never about just staying away from one nutrient. It is always more important to pay attention to what you ARE eating.

Oxalate is only one (possible) piece of kidney stone nutrition. Eating too much protein, sodium and added sugar can all play a role too. (3)

Learn more about healthy eating for calcium oxalate kidney stone prevention.

7. You Are Taking Vitamin C Supplements

Oxalate in your food is only one source of oxalate in the body. Your liver can make oxalate from certain things including some proteins, fructose and vitamin C. Vitamin C is a big one. In fact, a study found that vitamin C was the biggest contributor to oxalate in urine! (4)

If you have high urine oxalate, stay away from all types of vitamin C supplements. Yes, cough drops included! Vitamin C that occurs naturally in food is not a concern. People who eat lots of fruit are less likely to have kidney stones.

8. Kidney Stones Weren’t Caused By Your Diet

Lastly, it is important to acknowledge the limitations of nutrition. Not all kidney stones are caused by what you eat. If diet is not the cause, changing it isn’t going to help prevent kidney stones. It is important to find a doctor who specializes in kidney stone prevention to figure out the cause of your kidney stones and determine if eating (or avoiding!) certain foods will help you stay stone free!

Happy Eating!


38 thoughts on “Top 8 Reasons You Keep Getting Kidney Stones On A Low Oxalate Diet”

  1. I just came across your website. You seem to have a balanced approach. I like that. My 24 hour urine test showed 90% calcium oxalate and 10% calcium phosphate as of the end of November. It took me forever to get some clear answers concerning diet changes. My PC, urologist or nephrologist could tell me how to change my diet except for following “the list” and dietary recommendations. They all referred me to see a nutritionist, but none that I have been referred to specialize in kidney stone prevention. So grrrrr has been my favorite term when dealing with this. I did the “normal” dietary changes…limiting/eliminating very high oxalate foods, increasing dairy products and water/fluid intake. Hopefully I can keep another stone from forming. 2 months of pain, and 2 surgeries was not fun. What I am inquiring about is if there a site or list of nutritionist who specialize in kidney stone prevention even if I have to go outside my insurances preferred network? I know you offer services yourself, but I would prefer to meet someone face to face. If all else fail, I may need to sign up for your course. Thanks.

    1. Melanie Betz MS, RD, CSR, FAND

      Hi Lesha,
      I’m so glad you found me! I truly only know of a handful of other dietitians who specialize in stone prevention nationwide, and all are at large institutions and don’t take patients outside of their doctor referrals. There is a SURPRISING lack of kidney stone dietitians – which is exactly why I do what I do! This is also why I started a stone training for dietitians – to do my part to rectify the problem. I’d love to help you figure all of this out in the course! I also love that you’ve already picked up that my approach balanced – this made my day!

  2. Brenda Southerland

    Hey Melanie – appreciate all the good information you share. I tested positive for high urine calcium then next urinalysis I tested high for urine oxalate instead ( quit taking a calcium supplement prescribed for my osteopenia) after two kidney stones- about a year apart. I have had urinalysis redone 2 more times over the years and number’s definitely look much better – but I have developed two more stones – just waiting ( one 4 mm and one 3 mm as of last year.) I really watch my oxalates, salt and sugar, drink 2-3 liters a day – try real hard, drink oat milk ( allergic to cow milk I found out) eat a lot of cheese and eat Greek yogurt to help with upping my calcium. What else can I do – should I get another MRI to check on stones ? Get another urinalysis? Last one was over a year ago. Even saw a dietitian and she agreed with the changes I had made with very little recommendations. Also start each morning with lemon water. Urine citrate was low on some of the tests but urologist just made a note to increase citrate. Also osteopenia has gotten worse with latest bone density test. Any suggestions?

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Brenda! Whew – you have been through a lot! It sounds like there are a few other things we could work on – but I can’t know for sure without looking at your complete 24-hour urine test. Have you considered joining Kidney Stone Nutrition School? This is how I help people put together their own personalized kidney stone prevention plan. I’d love to help you figure all of this out!

  3. Hi
    I has a lithtripsy last May for a 6mm stone, but was left with 4mm stone. Started having discomfort on my left side where remaining stone was lodged, does that mean it wants to come out? Been watching diet, but does flare-ups happen when a stone is still there?
    Thank you for your help.

    Rosemarie Tapia

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Rosemarie! I’m sorry you’ve been having stone symptoms. Depending on where that stone is, it could cause discomfort. I really can’t comment on if that means it is getting ready to pass or not – that is dependent on SO many factors. I’d ask your urologist, who is MUCH more trained than me on this type of question, and is familiar with your situation. Dietitians really come in when we talk about preventing more stones, and stopping those stones you have from getting any bigger! Best wishes to you!

  4. Hi Melanie,
    Thank you for all your helpful information! About a year ago at the age of 64 I had my first kidney stone, a 5mm which was analyzed as composed of oxalates. I managed to pass it and have been trying to follow a lower oxalate diet and drink more water ever since, although I still struggle to drink enough water every day. A recent ultrasound showed that I now have a 2mm kidney stone in my right kidney, like a time bomb just waiting for the worst possible moment to go off. What I’m wondering is, if I’ve managed to make it to 64 years regularly eating high oxalate foods (spinach, chard, almonds, chocolate, etc.) and never getting enough water before my getting my first kidney stone, how is it possible when I’m finally taking preventive measures that now I’ve developed another one? Could it have already been there a year ago? The CAT scan didn’t show it back then. Can a body that could once handle oxalates suddenly change to how it processes them? Or is there another explanation? I am really confused about what to do. Also, passing that 5mm stone was the worst pain of my life, with the POSSIBLE exception of childbirth. If/when the 2mm leaves the kidney and gets stuck as the last one did, will the pain be as bad? Thanks for your help!

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Lynn! You are so welcome. I’m glad this information was helpful. I really can’t say what likely caused your stones without knowing more about your history and reviewing your 24-hour urine test. I will say that a low oxalate diet is NOT the key to stone prevention for most people – there is usually something else much more important going on in that 24-hour urine test that we can improve with nutrition changes (yes, even if your stone was primarily calcium oxalate). I’d love to meet you and help you know what you can do to prevent more stones in Kidney Stone Nutrition School!

  5. Hi Melanie, I am 61 and have had two calcium oxalate stones removed – one two years ago, one just recently. ESWL did not work for me at all so they both had to be surgically removed which was awful. I have tried to follow your advice – limit high-oxalate foods, drink lots of water (I can’t manage 3 liters per day but most days I manage two liters), limit added salt, include calcium in my diet, etc. I am about to have a urine analysis done so hopefully I will get more valuable information. My question is this: I am low in vitamin D, and my doctor wants me to take 2000 IU/day of vitamin D3. I can’t find clear information online about whether taking vitamin D might increase the likelihood of forming more stones. Do you know the answer to this? Thank you so much for your help!! Julie

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Julie! It sounds like you’ve made tons of wonderful changes. That urine test should help you and your dietitian understand what is most important for you to prevent stones. There are issues with very large doses of vitamin D taken for long periods of time. However, some people do need vitamin D supplementation. Vitamin D is really a person-by-person case!

    2. Hi Julie, I was told by my Endocrinologist that I shouldn’t have more than 50ng/ml on my bloodwork because it can cause kidney stones. I take a supplement about once every 2 weeks. I have hypothyroidism so not sure if that makes a difference in how the vitamin D affects my stone production.

  6. I have had the 24 hr. urine test in April 2022. It showed 100% calcium oxalate. Later I had a ultra sound had had a 9mm stone.
    Now I just did the 24 hr. test. Somebody forgot to test the oxalate. I also had an ultra
    sound test yesterday and they said I had no stones. How can that be?

    1. Melanie Betz MS, RD, CSR, CSG

      Ugh! How frustrating that oxalate didn’t get put on that test. Each lab is different, so I can’t say how that happened. I would certainly recommend reaching out to your doctor to get a re-test. That urine oxalate is a SUPER important piece of the puzzle!

    1. Melanie Betz MS, RD, CSR, CSG

      I don’t recommend multivitamins for most people as most of us don’t really need them! If you eat a balanced, varied diet, it is easy to get enough vitamins and minerals through actual food. I’m definitely a food first dietitian whenever possible!

  7. I’m so excited to read all of this!!! I have argued my doctor for years now I was doing everything correctly when it come to me mass producing stones… my 2 24hr urinalysis come back that my urine citrate and PH was the only thing off… I’ve been on potassium citrate pills for a year now but idk if they are helping just yet… had to have one removed Tuesday and it’s so terrible! It was 8x3mm and had been stuck for 4-5 weeks… the stents are terrible… it just really sucks to live like this…

    1. Melanie Betz MS, RD, CSR, CSG

      I’m so glad! There is truly no reason to limit oxalate if your oxalate is normal on a 24-hour urine test. But, there are definitely things you can do nutritionally to address that citrate and pH! I’d love to help you understand what would actually matter for stone prevention for you! Definitely check out Kidney Stone Nutrition School!

  8. I pee out once twice every other weeks stones. they are a reddish color but feel like stones. Dont drink hardly any water. Have kidney stone history. Had lithtripsy and telescopic surgeries. When i poop the stones come out more. But i still urinate the stones its just that pooping seems to push them out easier.

    1. Melanie Betz MS, RD, CSR, CSG

      I hope your doctor comes up with a wonderful kidney stone prevention plan for you! That is a lot of stones to deal with!

  9. Melanie , thank you for helping all of us with your knowledge about Kidney Stones. My world was turned upside down on 11-09-2021 when I wound up at the Hospital emergency room not knowing what to tell them what was wrong with me .Diagnosis: uti . Ct scan found a large kidney stone, stuck in my left kidney track . Two more hospital stays later and I still have my hateful stone to be blasted on 01-31-2022 . I have had such a run around,I am very discouraged. I will let you know what happens. Thank you for letting me rant.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Frances – I’m so sorry to hear about what you’ve been through the last 2 months. I know it’s not much consolation, but know that you definitely aren’t alone! I’d love to help you learn how to prevent more stones from happening in the future. The first step is make sure your doctor orders a 24 hour urine test, and then we can really dive into how nutrition can help you!

  10. I’ve been told I have calcium oxalate crystals in my urine, but I already eat very little meat, chocolate, or many of the other foods listed as causes. I already drink large quantities of water and do not drink soda. I also rarely have dairy due to a lactose intolerance. I do eat lightly salted almonds and drink almond milk frequently, is this enough to cause the crystals? Also, how long for calcium oxalate crystals to pass? Currently only very small crystals with clear to lite yellow urine

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Ashlee! Nutrition is no always the cause of stones – LOTS of other things could be the root cause of what is going on. Every body is different, so it is really hard to know if that is “enough” to cause stones or not. I would suggest checking out this article about good calcium sources for calcium oxalate kidney stones to maybe find a better option than almond milk! The time it takes for stones/crystals to pass is really different based on their size and where exactly they are – so that is a better question for your doctor!

  11. Hi Melanie, thank you for your articles and a great deal of valuable information about kidney stones. I have had kidney stones twice a few years ago. I had a lithotripsy five years ago removed a 8mm stones. Six months ago, the x-ray showed that I had two 4mm stones in my left kidney. According to the 24-hour urine test report, my calcium UR was 364, Ph Ur was 7.1. Brushit was 3.26. The rest of them were within normal. The result is Hypercalciuric Nephrolithis sis. My urologist told me that I could eat anything except anything with Calcium.
    I am confused with his advice.
    Please help. Thank you so much.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Jean! Thank you for your comment. Avoiding high calcium foods for hypercalicuria is somewhat outdated advice. The American Urological Association recommends making sure calcium intake is adequate for people with high urine calcium for bone health and to help keep urine oxalate low. I would ask your doctor about the recommendation to limit high calcium foods and send them to my site.

  12. I cannot reach the 2.5 liter/QD for urine output. My intake of fluids is 2.5-3.0 liter /QD. According to my Nephrologist, I live in Thailand, my average of 1.5 liters per day is ok. Confusing as the recommendation is clear for 2.5.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Robb! Everyone is different – and some people are unable to make the recommendation. You just do the best you can!

  13. Thank you! Thank you! and Thank you! This information is amazing and needed. You are doing a great thing by helping people understand what they should and should not do. You have helped me a great deal and I really appreciate it!
    Doing a 48hr urine collection right now and hoping it will be different than 6 months ago where the oxalates in my urine were 4 times higher than normal.
    Again, thank you sooo much Melanie

    1. Melanie Betz MS, RD, CSR, CSG

      Thank you so very much for your comment and for sharing Marcy! It makes my day to hear that my content is actually getting read and is helping people. Good luck getting those oxalates down! Starting to stay away from those really high oxalate foods and getting enough calcium should help!

  14. Valerie Bottega

    Really great content and I LOVE your graphics! As they say, a picture is worth a thousand words, especially for all us visual learners!

    1. Melanie Betz MS, RD, CSR, CSG

      Thank you SO much Valerie! I tend to use my “Mr. McStoney” graphic a lot…mostly because I just LOVE him! haha. I’m glad the graphics are helpful!

  15. Hello Melanie, thank you for another helpful article. I am so relieved to have found your website. There is so much confusing dietary info for new kidney stone patients.

    1. Melanie Betz MS, RD, CSR, CSG

      Thank you very much Kimberly! I’m so happy you find my website helpful. I appreciate you sharing!

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