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Update on Cinnamon for Blood Sugar Control

Cinnamon can no longer be considered a safe and effective treatment for diabetes.

April 17, 2013 |
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Supplementary Info

Sources Cited


Images thanks to CINNAMON VOGUE


The use of cinnamon to help treat diabetes remains controversial. We know that cinnamon is so good at controlling one's blood sugar that you can cheat on a diabetes test by consuming 2 teaspoons of cinnamon the night before your glucose tolerance test. Basically they make you drink some sugar water and see how well your body can keep your blood sugar levels under control, and if you eat those two teaspoons right when the test starts or 12 hours before you can significantly blunt the spike. A half teaspoon doesn't seem to be enough… but about a teaspoon a day appears to make a significant difference. A review of the best studies done to date found that the intake of cinnamon by type 2 diabetics or prediabetics does lower their blood glucose significantly. So what's the controversy? Well, as I described before, cassia cinnamon, also known as chinese cinnamon, or probably what you're getting at the store if it just says cinnamon contains a compound called coumarin which may be toxic to the liver in high enough doses. Originally, the concern was mainly for kids during Christmas-time, where they might get an above average exposure, but more recently some researchers suggest that kids just sprinkling some cassia cinnamon on their oatmeal a few times a week might exceed the recommended safety limit. The bold values here are above the recommended upper limit. For little kids, just a quarter teaspoon of cinnamon a few times a week may be too much, and if they're eating that cinnamon sprinkled oatmeal more like every day even adults can bump up against the limit. So a teaspoon a day of cassia cinnamon might be too much for anyone, but no problem, just switch from cassia cinnamon to Ceylon cinnamon and you can get the benefits without the potential risks, right? Without the risks, yes, but we're not sure about the benefits. Nearly all of the studies showing blood sugar benefits of cinnamon have been done on cassia. We've just assumed that the same would apply for the safer cinnamon, Ceylon, but only recently was it put to the test. Owing to the presence of that toxic component, the Federal Institute for Risk Assessment in Europe has warned against consuming large amounts of the cassia cinnamon, suggesting a switch from cassia cinnamon to Ceylon cinnamon, also known as true cinnamon. But we don't know whether or not the true cinnamon has similar benefits, until now. We saw that nice blunting of blood sugars in response to cassia cinnamon, but in response to Ceylon cinnamon, nothing. Bummer.  In fact they're thinking maybe that potentially toxic coumarin stuff was the active ingredient in the cassia cinnamon all along, so take out the toxin, you take out the benefit. So they conclude yeah, it's great that health authorities are recommending the switch, however, the positive effects seen with cassia could then be lost. So should we just give up on going out of our way to add cinnamon to our diet? No, I think it's still a good idea to shoot for a teaspoon a day of Ceylon cinnamon, since there's a bunch of other benefits linked to cinnamon besides blood sugar control, not the least of which is it's potent antioxidant content, in fact one of the cheapest food sources of antioxidants, beating out cloves, and just under purple cabbage. But cinnamon can no longer considered a safe and effective treatment for diabetes. Either you're using cassia cinnamon and it's effective but may not be safe; or you're using Ceylon cinnamon which is safe, but does not appear effective. But look, even the cassia cinnamon only brought down blood sugars modestly. In other words, only as good as the leading diabetes drug in the world, metformin, sold as Glucophage. Yeah it may work as good as the leading drug, but that's not saying much. The best way to treat diabetes is to attempt to cure it completely, reversing diabetes with a healthy diet.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Jonathan Hodgson.

To help out on the site please email

Dr. Michael Greger

Doctor's Note

The Antioxidants in a Pinch video I'm so proud of can be found here. The Safer Cinnamon is where I originally brought up the coumarin issue. What about the Oxalates in Cinnamon? Not a problem, but the oxalates in too much turmeric may be a concern. Superfood Bargains is where I ranked foods in terms of antioxidants per unit cost.

I talk more about the potential potency of plants in general in Power Plants and more about spices in particular in videos such as:

Amla Versus Diabetes explores the use of Indian gooseberries as a way to help control blood sugar, though the best way to deal with diabetes is to prevent and treat it with a healthy diet. Books I would recommend (in order of publication) are Defeating Diabetes, Dr. Neal Barnard's Program for Reversing Diabetes, and The End of Diabetes.

As you're making your Healthy Pumpkin Pie, don't accidentally add too much nutmeg, the subject of my next video Don't Eat Too Much Nutmeg.

For more context, check out my associated blog posts:  Cinnamon for DiabetesNutmeg Toxicity, and Tarragon Toxicity?

If you haven't yet, you can subscribe to my videos for free by clicking here.

  • Brian Humphrey

    Thanks Dr.Greger for the brain nutrition! Love it!

  • Ilana

    I don’t get it – how are we supposed to know which cinnamon we have and how do we buy the right one?

  • RuthSC

    What effect does Saigon cinnamon (on every grocery store’s shelves of spices bearing the McC brand) have compared to Cassia and Ceylon varieties?

    • John B

      I’d like to know the answer to this one too. I was using Saigon cinnamon before Dr. Greger’s earlier video which recommended Ceylon cinnamon, and I prefer the taste of the Saigon cinnamon available and Costco.

    • Mack

      Here’s your answer John, and I’m afraid it’s not good news; Saigon cinnamon is relatively high in coumarin.

      • John Smith

        Thanks Mack. I won’t be using Saigon any longer.

        • Marilyn

          Tim Ferris tested all three by wearing a continuous glucose meter in his side so he could tell what his blood sugar was doing after everything he consumed. This is what he found:

          “I tested three species of cinnamon as powders for glycemic index (GI) response: Ceylon cinnamon (Cinnamomum verum or zeylanicum, also referred to as “true cinnamon”), Cassia cinnamon (Cinnamomum cassia or aromaticum), and Saigon cinnamon (Cinnamomum loureiroi, also known as Vietnamese cinnamon).

          Though Cassia is thought inferior to Ceylon or completely ineffective in some bodybuilding circles, it has lowered glycemic response in both published studies and in my experience. This is fortunate, since Cassia is what is most often found at coffee shops and restaurants if you ask for
          “cinnamon.” I found Saigon cinnamon to be most effective, with Cassia in close second place and Ceylon in much further third place.”

          Dr. Amen also looks at scans of brains all the time and he recommends cinnamon, so it can’t be that bad. I’m going to stick with the Saigon, since I bought a pound of it on iherb. If anyone needs a coupon, PEY 561 works.

  • Denise Goode

    How does 1 teaspoon of cinnamon compare to OTC capsules dosed in mg? Are the OTC capsules usually cassia or ceylon?

  • Lisa Meyerholz Owens

    How do you know which cinnamom you are getting? If I am buying organic does that make a difference? Thanks Dr. G..You are helping me save my life—really…THANK YOU! Lisa O in NJ

    • Marilyn

      I bought Saigon cinnamon specifically at iherb. See my post above for Tim Ferriss’ results of all three cinnamon types.

  • Thea

    For those who are asking about what kind of cinnamon you are getting, you can order the ceylon from on-line if you want to be sure. I got mine from Amazon after watching one of Dr. Greger’s earlier videos.

  • Thea

    QUESTION: The video gives an awesome history an explanation of why the safe cinnamon is not likely going to help with diabetes problems. However, video goes on to say that cinnamon has other great properties, so it is still worth it integrate ceylon into our diet.

    Well, just as past diabetes research focused on cassia, doesn’t it seem likely that past research on other benefits of cinnamon also focused on cassia? So, how do we know which, if any, benefits that ceylon has?

    • Toxins

      The major benefit Dr. Greger is referring to is the antioxidant content which remains quite high.

      • Thea

        Thanks Toxins!

  • Kim

    What if you are consuming 1-2 cups of spinach per day? Would you recommend reducing or not consuming turmeric? (I am considering taking a turmeric supplement to help arthritic pain.)

  • dimqua

    What about eating a two teaspoons of cassia every two days? This can be harmful for adults?

    • R Ian Flett

      The recommended maximum consumption of ground Cassia for liver toxicity is half a teaspoon a day based on some sources. However, as the video suggests, that may also be too little to get the insulin sensitivity benefits. We really need more research.

      • dimqua

        Therefore, is it ok to eat a teaspoon of cassia three times a week or less?


  • Plantstrongdoc

    I guess no surprise. No magic “pill” in nature either. Cinnamon and SAD will not improve your health, if you have type 2 diabetes, nor metformin and SAD. Changing your diet to a low fat, plantbased diet, and moderate exercise will surely improve your health, maybe even cure type 2 diabetes.

    • Marilyn

      Why do so many people target fat instead of sugar in diabetes? Sugar is the culprit, healthy fats are necessary for health.

      • Thea

        re: “Why do so many people target fat instead of sugar in diabetes?”

        Because the best studies show that sugar does not cause diabetes. Sugar problems are a symptom of diabetes, not the cause. If you want to learn more about the cause of diabetes, I highly recommend the book: “Dr. Neal Barnard’s Program For Reversing Diabetes.” Dr. Barnard’s plan is 3 times more effective than other diet plans and he stresses truly low-fat.

        re: “…healthy fats are necessary for health.”

        While this sounds logical on the surface, “the devil is in the details.” Your statement would only be true depending on how you define healthy fats and at what amounts. Usually people who push “healthy fats” are actually pushing non-healthy fats (oils of one type or another) and amounts that are way too high. Plantstrongdoc’s word choice of “low-fat” is far more likely to lead someone in the right direction if they want to adopt a healthy diet.

        If you want to learn about what constitutes a healthy diet, you are in the right place. Keep watching more videos here. Also, check out the PCRM 21 Day Kickstart program. Good luck.

  • John

    so Saigon cinnamon is no good either?

  • R Ian Flett

    If you look carefully at the picture of the two types of quills you will note that the Ceylon variety curls in from both edges, whilst the thicker, woodier and darker, Cassia scrolls only from one edge to form a single spiral. The Ceylon variety also usually has more inserted inside each scroll and often has frayed ends. Because the Cassia is much cheaper you are more likely to find it used for the ground cinnamons, so unless the packaging specifically mentions Ceylon, then, as Dr Greger suggests, assume that its the cheaper and potentially toxic Cassia. If it’s origin is China or Indonesia, then it’s Cassia.

    It used to be thought that cinnamon was high in chromium, which helps in glucose control, but this may be due to the association of cinnamon supplements that also contained chromium picolinate that were popular quite a while back, but were later discredited as weight loss supplements. In the Cassia type it’s still uncertain as to whether it’s certain polyphenols or the coumarin that’s improving insulin sensitivity.

    Keep your cinnamon, especially the powder, in the fridge as it does go off.

    I use a Ceylon cinnamon stick with cloves in my water jug to create an infused water for my teas and coffee. Beware that the second boiling will violently boil over due to the cloves reducing surface tension. You can keep adding water for a day or two, but only reheat to below boiling.

    • Thea

      re: “Keep your cinnamon, especially the powder, in the fridge as it does go off.”

      That’s a great tip! When I bought the ceylon from the web, it came in a pound bag – really a LOT for what I need. I’ve only used a tiny fraction of it, and it’s sitting in my cupboard. I wonder if it’s gone bad by now? Do you know how to tell? I had thought that it might loose potency over time, but I hadn’t considered it going “bad”.


      • R ian Flett

        Apparently, as it goes off, it loses much of its typical aroma.

  • Pat

    You can buy a pound of organic Ceylon cinnamon at for less than the price on And if you use code POD782, you can get another $5 or $10 off, depending on the size of your order. Also, click on “freebies” at the top of the page, and you can select a free sample of something.

  • William

    I read that cinnamon extract with Cinnulin PF can give you the benefits of cassia cinnamon without the coumarin, because it is the water soluble form of cassia which does not contain the coumarin, the latter residing in the dry portion of the spice.

  • Mo jean

    Thanks for cutting thru the clutter. Now I know why I purchased Ceylon and left Cassia on the shelf.

  • Ale Flechas

    Thanks Dr. for all your advice, I’m Ale I’ve been diagnosed with Polycystic ovary syndrome (PCOS) my dad has diabetes type 1, I was tested for hypoglycemia and was found to be positive, as well as high cholesterol, I didn’t expected my test to have those results as I try to eat really healthy exercising couple of times a week, I’m taking my pills in halfs (850g) Metformin at lunch and dinner, I’m also taking birth control pills to regulate my period, I also suffer from constipation. I wonder if you’ve got any advice??? many thanks

    • SFChutzpah

      Nothing is better for constipation than oven roasted sweet potatoes. Really. :)

  • Carlo

    Looks likey C. loureiroi and C. burmannii are dangerous as well:

  • Ingrid Du Preez-Japp

    Thank you Dr. Greger! Due to having given my husband and I this important information, I am now about to order my first bag of Ceylon Cinnamon! May God bless you! :))

  • SFChutzpah

    When my doctor told me my blood sugar level was too high, I started using cinnamon (in bulk, sprinkled on steel cut oats) from the Rainbow Grocery here in San Francisco. Whatever kind of cinnamon it was, it certainly worked beautifully. The Rainbow Grocery is just of of those stores you trust, so I’m sure it was fine.