Doctor's Note

For more on oxalates, check out these videos:
Asparagus Pee
Who Shouldn't Consume Curcumin or Turmeric?

And check out my other videos on spices

Also, for more context, check out my associated blog posts: The Best DetoxBreast Cancer and DietFighting Inflammation With Food SynergyDr. Greger's Natural Nausea Remedy RecipeCinnamon for Diabetes; and Nutmeg Toxicity.

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  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on spices. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

    • mrkevinlei

      Hello Dr. Greger,

      I just stumbled upon this website and it’s fantastic! I recently started university and learned about looking for primary research articles as opposed to secondary ones online for the most accurate information regarding nutrition. However, one problem is that I am not yet so adept at understanding many technicalities of primary research articles. This website does an amazing job at summing up information which would otherwise take me quite a while to decode!

      Anyway, I’ve been using turmeric in a recipe that I’ve been eating daily (about half a tablespoon). This is obviously more than the “safe” amount recommended above, but I’ve heard that turmeric is highly anti-inflammatory, so I don’t want to stop eating turmeric all together. Is there a way to counter the effects of a high oxalate diet and prevent kidney stones while still continuing to eat turmeric daily? For example, are there foods rich in a certain nutrient that can prevent oxalate-induced kidney stones?


      Kevin Lei

      • Michael Greger M.D.

         I am so glad you stumbled! That’s always been my dream, to act as “translator,” to de-jargonize and bring to light science that would otherwise remain neglected due to a lack of commercial interest. There’s lots of plant-foods that are anti-inflammatory (see so you don’t have to risk the health of your urinary tract, but if you insist on consuming that much drinking lots of water in hopes of preventing stone formation might mitigate the risk.

    • Sunny White

      Hi, I was really bummed to read your article on turmeric. I just recently found out if I take 2 capsules of Organic India tumeric twice per day my joint stiffness and soreness leaves like magic. I am able to do yoga poses I had long since given up. Needless to say I was ecstatic, that is until I read about the oxalates. I was wondering if there is a higher incidence of kidney problems in India. How do all the people there that eat lots of curry survive? As if that news wasn’t bad enough I put a tsp. of cinnamon in a smoothie almost every night and often add nutmeg to it. I think I am doomed. Any (hopefully reassuring) feedback on my comment will be greatly appreciated.

  • lebepotter

    Cinnamon may be safely low in oxalates, but it may be dangerously high in hepatotoxic coumarin, according to Wikipedia and its German governmental cited source. Coumadin in cassia cinnamon would exceed the German tolerated daily intake at `1 tsp cinnamon per day for a 135lb person. I’m smaller than that, and have sometimes exceeded that dose, and had elevated liver enzymes in recent blood labs (better at the next visit). I will cut back– or switch to Ceylon (true) cinnamon, which is more expensive than cassia cinnamon, but is said to contain negligible coumarin. Of course, we don’t know which species of cinnamon may contain what proportions of beneficial phytonutrients. Plants are complicated. We need an authoritative “Which is the Best Cinnamon?”(!) May not be easy: coumarin levels can vary wildly, even in cinnamon bark samples from the same tree (

    • sf_jeff

      Later videos from this site recognize this issue and his recommendations are updated. He currently recommends Ceylon but not Cassia.

  • As I use a lot of spices in my food and turmeric root powder is one of my favorites, I was alarmed by the red-light associated with it in this report. Sometimes I use up to a tablespoon at a time, but then go for days without using it at all. While the information describes the benefits, the point that consuming “large doses” (3 grams?) to increased risk of kidney stones is certainly a serious consideration. Can you point to further details on this risk, how to continue using this spice without having it be “unsafe”, or any way to offset the oxalate formation resulting from too much turmeric?

    Also have you come across anything on Goldenseal root powder – another yellow root that is claimed to have some of the same beneficial effects? It does not appear to include curcumin as one of its components. (As a side note, goldenseal is about 9x the cost of turmeric powder!)

    • herbalist

      Goldean seal has an unfortunate side effect of depleating vitamin b12. Thus use it very sparingly more so than even tumeric.

    • sf_jeff

      I use about 1-2 tsp in “soup for a week” and thought *I* was using a lot.. :)

  • vetstud

    I just had a kidney stone and really don’t want to have another one. I looked online and there are conflicting things about what I should eat to prevent a recurrence. What is the best diet?

    • Michael Greger M.D.

      I’m going to assume you have what’s called idiopathic calcium nephrolithiasis (but if you can actually catch a stone and have it analyzed your physician can make more specific recommendations). ICN, the formation of calcium oxalate stones (sometimes mixed with calcium phosphate) accounts for about 80% of cases (though you should see your physician to rule out a variety of hereditary and acquired diseases that can cause those in the 20%).

      The most important thing folks with ICN can do is drink lots of water, at least 2 liters a day to dilute the concentration of calcium, oxalate, and uric acid in your urine to decrease the likelihood of stone formation and flush away seeding crystals. Water’s probably the best, but if you are going to do other liquids OJ is preferable to grapefruit juice, apple juice, and tea.

In terms of food, according to the latest review on the subject, the most important thing is to reduce meat consumption (vegetarians may only have half the kidney stone risk. The reasons given why animal proteins are bad is because of hypercalciuria, hyperoxaluria, hyperuricosuria, hypocitraturia, and the acidification of the urine. You should also cut down on salt, and the more fruits and vegetables the better–they tend to have a high water, potassium, and magnesium content; a low sodium chloride content; and a high urine alkalinization power because of the presence of bicarbonate and citrate. I would warn against megadosing with vitamin C (as you’ll see across the internet) as this may exacerbate stone formation.

      • Kristy

        My husband just got out if the hospital for kidney stone removal. The paper they gave us says it can be caused by meat, coffee, tea and green leafy vegetables. I don’t understand. If meat is bad and so are greens what do you eat? Fruit?

        • Pamela

          Leafy greens vary in their oxalate content and probably their oxalate bioavailability. Here’s a link I found with lists of low and medium oxalate greens – there’s lots to choose from!

        • fruitbat

          Saying that leafy greens increase kidney stone formation is propaganda. The reasoning is that since SOME greens such as parsley and spinach contain calcium oxalate, and kidney stones are usually made of calcium oxalate, therefore eating greens must be the source and cause of this calcium oxalate presence. However there is no evidence that consuming leafy vegetables actually causes kidney stones. The only thing that has been proven to increase the risk of kidney stones is the consumption of animal products. The body has to leech calcium to neutralise the excessive sulfur in meat. Vegetables and fruit have been shown to have a preventative effect regardless of oxalate content. Take all advice from your doctor with a pinch of salt – remember Big Pharma and your doctors financially benefit from illness.

  • Michael Greger M.D.

    Also be sure to check out my associated blog post Breast Cancer and Diet!

  • Almondine3

    Hi! Thanks for the great posts. I just came across this article on cinnamon polyphenols
    And I’m curious about the effect of different types of cinnamon on both blood sugar and inflammation. I recognize that there is a difference between true cinnamon (ceylon) and cassia, and I believe the authors of the study I’ve provided the link for use Cinnulin PF which is a cassia derivative. However, it’s hard to tell from Cinnulin PF’s manufacturers which plant it derives from. Do you have an idea of the different benefits of different cinnamon plants, specifically how they vary in polyphenol contents? I eat quite a bit of the Vietnamese variety (Cinnamomum loureiroi) and am especially curious about this one (compared to others). I’m a biochemist, so feel free to go at it with the scientific terminology.

  • Sandy Smith

    I had posted a question concerning taking turmeric and your reply included a link to this video and said you do not recommend capsules of turmeric. In the video you mention a dose of 3 grams. My husband’s dose was recommended at only 500-1,000mg/day. Does this amount affect your recommendation? FYI -He is dealing with a rare appendiceal cancer and his body over-expresses the COX-2 enzyme which turmeric seems to help with according to one of the studies you cited. Thank you!

    • Hello! I’m curious–how is your husband now, if you don’t mind my asking?

  • Ray Paquette

    I just had two thyroid test that showed I have a hypothyroid. I am a male, 57 yrs. old and have been eating a vegan diet since 1988. I have yearly blood test, and everything looks good usually. The last few months I have been doing a 1/4 teaspoon of amla and one or two teaspoons of cinnimon a day, I do 5 drops of silica a day, but I have been doing that for years. I just started 1 tablespoon of dusle and 1 brazil nut a day. I stopped taking amla and cinnimon. Do you think the amla or cinnimon could have anything to do with thyroid being high?

    Thanks, Ray

  • Vincenzo

    If instead of taking a teaspoon of turmeric/day, I take 400mg of its active ingredient curcumin (Curcumin (Curcuma longa)(rhizomes) (containing three curcuminoids: curcumin, bisdemethoxy curcumin, demethoxy curcumin)[standardized to contain 95% curcuminoids] with 100mg of Lecithin (soy) for absorption as a long term supplement regimen, will that be cause of any toxicity including liver toxicity?

  • Katie

    Is there a maximum amount of cinnamon at is safe each day? I have been having at least 3 tablespoons each day lately of Ceylon cinnamon, is that too much? Thanks in advance. really appreciate all of your videos.

    • Katie

      Woops, autocorrect changed a few things, it should read “Is there a maximum amount that is safe each day? And I really appreciate all of your videos.”

    • Mike

      3 tablespoons! That’s bucket loads imo :P

      I would say a good metric is to look at how such things are harvested (I have no clue) – if you can’t extract it that fast with your hands or simple tools the chances are consuming that much in short spaces of time may have side effects? That’s just the way I look at it anyway. Similar to how I imagine paleolithic man with a salt shaker or a bottle of olive oil.

  • Billy Boy!

    What about coconut oil, meat, and water? Some say there are great benefits from consuming these.

    • Susan

      Coconut oil and meat are high in saturated fat which clog your arteries amongst other things.

      Water than has been purified with carbon reduces certain pesticides/herbicides and industrial chemicals and water that has been purified with Reverse Osmosis as well as a carbon filter is even better. It helps reduce the fluoride and other heavy metals from your drinking water source.

      I use a Multi-Pure 750 plus RO to reduce the poisons in my water, which includes aluminum sulfate added by the water company to clarify the water, but found to damage to brain. It is linked to Alzeheimer’s Disease ane dementia in a myriad of scientific studies.

      RO plus carbon filtration is recommended by Dr. Neal Barnard, M.D. in his book,

      Power Foods for the Brain: An Effective 3-Step Plan to Protect Your Mind and Strengthen Your Memory

  • Ally


    Jarrow Formulas Curcumin 95 ( low in oxalates?


  • Pamela

    Hello Dr. Gregor,

    My mother-in-law, 87, suffers from osteoarthritis that is sometimes very painful and recently started taking a micronized/”nanotized?” (“for better absorption”) form of curcumin. Your posts on nanoparticles and oxalates both have me worrying that this is going to do her more harm than good.
    What is your opinion?
    Thank you for all the work you put into your website; it’s such a great resource.


  • Lynn

    Just wanted to say I discovered your videos about a year ago, and they have really been educational! You deliver the right amount of info in language we can understand without dumbing it down. I think of your work as a blessing from God. People often ask me how I know so much about nutrition and its impact on health–I tell them about your work and website. Thanks!!!

  • Ronald Chavin

    Turmeric has been shown to effectively block nitrosation (the formation of reactive nitrogen species>>>cancer-causing nitrosamines). I swallow my turmeric together with my wakame, which despite my soaking in water, still might contain some salt. The good news is that all “brown” seaweeds contain phlorotannins which have been shown to effectively block carbonylation (the formation of reactive carbonyl species>>>the formation of dietary advanced glycation endproducts):

    • Ronald Chavin

      The good news is that vegans have a much lower risk of developing kidney stones than meat lovers. This despite the fact that an extremely wide variety of fruits, vegetables, nuts, seeds, whole grains, and berries are moderately high in oxalic acid>>oxalates. Meats tend to be low in oxalic acid and oxalates. Like phytate, oxalic acid is a beneficial antioxidant that, in addition to partly blocking the harm from free radicals, will bind to toxic heavy metals and help our bodies to excrete them:

      Conclusion: Don’t worry about oxalic acid or oxalates unless you are genetically predisposed to developing kidney stones or have already developed them.

  • Steve Kehoe

    Seen quite a few articles that say tumeric should be combined with black pepper to increase absorption into the blood. Without it they say absorption is very poor. Is this true?

  • Chicov

    Do the oxalates chelating effects of 1 teaspoon turmeric a day prevent magnesium supplement absorption? Is the chelation in the gut or in the blood, or in both?

  • Sunny

    I was basically bummed out after reading your article on tumeric. I just recently found out if I take 2 caps of Organic India tumeric twice pet day that it woks like magic to stop my stiffness and soreness. If I take any less than that it doesn’t seem to help. Their recommend dosage is 2 to 3 caps per day. Shouldn’t thy know about the oxalate problem? What about all the peope in India that eat large quantities of it? Please any input you can give me on this will be greatly appreciated.

    • steve

      This is very discerning, can’t take cinnamon or turmeric now, really?

      • Tommasina

        Steve, I think Dr. Greger is saying we should just be careful not to exceed 1 teaspoon of turmeric a day. Since cinnamon has only 10% soluble oxalates compared to turmeric’s 90%, we can probably eat more than a teaspoon of it a day, but I’m not sure about the exact quantity.

      • Azoraa Tre’lok

        I know, I have an odd craving for turmeric powder too.

    • Tommasina

      Sunny, how much is in 2 caps of your turmeric? It might be less than the 1 teaspoon a day that Dr. Greger recommends.

  • Linda

    I don’t normally consume a lot of cinnamon but today I had 2 or 3 tablespoons of cassia cinnamon in a paleo cinnamon bread that I made and munched on over the course of the day. Later I looked up real/not-real cinnamon and learned that cassia cinnamon has a lot of coumarin, that 2 to 3 tablespoons in a day is a very large amount, and also that large amounts can harm the liver. Can having this amount of cassia cinnamon one time cause liver damage? Do you recommend using silymarin or anything else to detox from it? Or is doing this one time not really something to worry about? Thanks very much for your help on this.

    • dogulas

      In case you didn’t see his more recent videos, yes, it is now recommended to not go over 1 teaspoon of Cassia/Chinese cinnamon a day. Better yet, just eat Ceylon cinnamon which is not toxic to the liver. Gotta just forget about using cassia cinnamon for blood sugar and enjoy the other benefits in ceylon.

  • KJP

    I have dropped my fasting blood sugar from 114 to 50 in 15 months. What can I do to normalize it to 65ish?
    No symptoms…

  • Alex

    HI Dr. G Im 24 and have been fortuanate enough to live next to a ginger and turmeric farmer but after this video im afraid ive been over doing it. I’ve been putting around 20 teaspoons in my smoothies everyday and hardly notice if I have enough fruit. If i lower my intake of oxalic acid can i help my kidney? I follow a plant based diet and try to be super healthy but this gotten me super concerned.
    Thank for any feed back.

  • Richard Feole

    I’m on a low sodium oxalate diet and also a diabetic. Can I take cinnamon caplets to lower my blood sugar. What will it do to lower my chances on making kidney stones?

    • Jennifer Drost, Physician Assi

      Hi Richard! :) Good question! Per the research Dr. G. cites above, only 10% of the oxalates in cinnamon get absorbed into the bloodstream, so if you were eating about a teaspoon a day (like they did in the studies), you should not have a significantly increased risk of stone formation. However, did you see Dr. G’s most recent post about cinnamon and diabetes? (Short answer, cinnamon is no longer recommended for treatment of diabetes). Hope this helps :)

  • cgwieder

    How much food with oxalate is too much? I drink about 6 cups of green tea a day & eat a large handful of spinach most days & use curry powder containing turmeric most days. Sometimes I eat 4 – 8 oz of raspberries in a day. I read about a man who drank 16 glasses of iced tea per day and had kidney failure.

    • Joseph Gonzales R.D.

      Hi cgwieder! Thanks so much for reposting your question. I really appreciate that. As I mentioned, I am doing a segment on oxalates and will include how much is “too much”. Check back on myQ&A page next week. Dr. Greger does have some info on this, too. Check out his Q&A page, as it is filled with information. More on diet and kidney stones and Who Shouldn’t Consume Curcumin or Turmeric?. I hops this helps. I know spinach and turmeric have more oxalates, but it doesn’t seem like you are overdoing it. Have kidney stones ever been a concern for you? Have you addressed these concerns with your doctor? Not trying to pry for more information just thinking out loud. I’ll definitely have more information and updated research by next week on oxalates.

      Best wishes,

      • S Slavin


        Was browsing around and saw this. Did you ever publish the segment on oxalates? The link you have up there (“my Q&A page”), doesn’t work.

        I’ve always wondered about the oxalate content of plant foods and kidney stones, and if eating one leaf over another is better, I’d like to know about it.

        • Joseph Gonzales R.D.

          Yes! I’ll put it up by the end of the week please check back on the RD page Friday evening. Thanks for the reminder

        • Joseph Gonzales R.D.

          Still working on, pal. And finding the person who originally asked about more information. The link did not work because the url for my RD page changed just recently. Here is a better link to my RD Page and you can also find it under the “Nutrition Questions” tab. if interested to know this is the question I am working on. I have been asked so many similar questions on oxalates and luckily Dr. Greger’s new videos on green smoothies and kidney stones make it easier to answer. He is going to edit the blog and then we’ll post! Just wanted to update you.

        • Joseph Gonzales R.D.

          Dr. Greger is back in action! Check out my new post on oxalates. Thanks S Slavin.

  • oceanwild

    [url=]Cinnamon oil[/url] Place a few drops of cinnamon bark on oil burners or diffuser. The pleasant aroma of cinnamon oil makes it a very effective as a room freshener. It is often added to potpourris. Add a few drops of Cinnamon bark essential oil to massage oil, it is also an anti-inflammatory substance, so it helps in removing stiffness of the muscles and joints. Cinnamon is also recommended for arthritis, and it is known to help in removing headaches that are caused by colds.

  • Nico Bennet

    I was wondering about taking Tumeric for migraines. I have read that Tumeric has anti nflammatory properties yet that it is also a vasodilator which could be bad for migraines. I’m trying not to overdo taking analgesics and would like to take curcumin or Tumeric but am afraid it could make my migraines work because of vasodilation! Help!

  • Marco Splendori

    hi @d@Michael_Greger_MD:disqus i’d like to know if eat large salads of swiss chard can be harmful for calcium erosion,kidney stones and so for teeth also, due to high oxalic acid content…what is its bioavailabilty? and …juicing vegetables contratrates oxalic acid? most researchers,as esselstyn,mcdougall and campbell do not raccomend juices in an ideal healthy diet

    what can you say about swiss chard and spinach….and oxalates in juices?

  • Ciaran Ryan

    Doc, spinach is also high in oxalates. Does high oxalates necessarily mean kidney stones? Or are there other factors in play?

  • gr

    I’m noticing that as one goes through life, one must constantly stay maintaining or doing better than maintaining.