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Does Cinnamon Help Lower Blood Sugars?

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 two teaspoons of cinnamon the night before your glucose tolerance test. That’s where they make you drink some sugar water to 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. Even 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 in my video The Safer Cinnamon, cassia cinnamon, also known as Chinese cinnamon (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 at high 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.

As you can see in the above video just a quarter teaspoon of cinnamon a few times a week may be too much for little kids, and if they’re eating that cinnamon-sprinkled oatmeal more like every day they can bump up against the limit for adults. So a teaspoon a day of cassia cinnamon might be too much for anyone, but can’t we just switch from cassia cinnamon to Ceylon cinnamon and get the benefits without the potential risks? Without the risks, yes, but we’re no longer so 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. That nice blunting of blood sugars we saw in response to cassia cinnamon disappeared when the researchers tried Ceylon cinnamon instead.† In fact, it may actually be the potentially toxic coumarin that was the active ingredient in the cassia cinnamon all along. Thus, sidestepping the toxin by switching may sidestep the benefit.

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 are a bunch of other benefits linked to cinnamon besides blood sugar control, not the least of which is it’s potent antioxidant content (as I show in my one of my favorite videos Antioxidants in a Pinch). In my Superfood Bargains video, where I rank foods in terms of antioxidants per unit cost, cinnamon comes out as one of the cheapest food sources of antioxidants, beating out cloves and coming in just under purple cabbage. What about the†Oxalates in Cinnamon? Not a problem, but the oxalates in†too much turmeric may be a concern. As you’re making a Healthy Pumpkin Pie with all that cinnamon, don’t accidentally add too much nutmeg, though, the subject of my follow-up video†Don’t Eat Too Much Nutmeg.

Ultimately cinnamon can no longer be 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. Note that 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). So yes, 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. †Books I would recommend (in order of publication) are†Defeating Diabetes,†Dr. Neal Barnard’s Program for Reversing Diabetes, and†The End of Diabetes.

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, again, the best way to deal with diabetes is to prevent and†treat it with a healthy diet.

In health,
Michael Greger, M.D.

PS: If you havenít yet, you can subscribe to my videos here and watch my full 2012 year-in-review presentation†Uprooting the Leading Causes of Death.

Image credit: CINNAMON VOGUE / Flickr

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Dr. Michael Greger

A founding member of the American College of Lifestyle Medicine, Michael Greger, M.D., is a physician, author, and internationally recognized speaker on nutrition, food safety, and public health issues. Currently Dr. Greger serves as the Director of Public Health and Animal Agriculture at The Humane Society of the United States. Hundreds of his nutrition videos are freely available at


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7:08PM PST on Feb 5, 2014

Important Question, Can someone answer? I have done a lot of research about Ceylon vs. Cassia cinnamon and Coumarin.

I have begun to drink quite a bit of Cassia Cinnamon Tea lately. Approximately 6 cups a day...I like it a lot. It does in fact suppress my appetite and I do believe it is helping me regulate my blood sugar levels, and I noticed this effect within 12 hours of drinking it regularly throughout the day.

I have read that Coumarin is Fat / Lipid soluble: so theoretically, if I brew a strong batch of
black tea with a Cassia cinnamon stick, and then discard the stick, I shouldn't be ingesting too much Coumarin.

My Question:

Am I correct in this assumption? I have read elsewhere that I am correct. And I now see a comment above mine that claims she is having no ill effects, but I have also read a lot of misinformation as well.

So, I do want to check.

I have also ordered Organic Ceylon cinnamon direct from Sri Lanka, via eBay. But the Ceylon cinnamon arrived today and it is a completely different kind of cinnamon. I really prefer taste and aroma of the Cassia Cinnamon.

My main concern and question is whether or not drinking large quantities of Cassia Cinnamon Tea is safe for my liver?

3:55AM PST on Dec 10, 2013

Great blogs buddy……… this will definitely assist me.

a1c chart

2:12AM PST on Nov 15, 2013

Yah totally agreed. Also, please check your blood sugar levels. You can use monitoring device these devices makes a lot difference. This is what I bought.

4:16PM PDT on Oct 3, 2013

What about Saigon cinnamon? How is that different from the Ceylon or cassia type?

4:03PM PDT on Oct 3, 2013

Too bad, I liked it in my oatmeal or cereal. I wonder where you can find the ceylon cinnamon, I would use that for all the health benefits you mention. Thank you!!

12:37AM PDT on Jun 11, 2013

mother nature is the best

11:48AM PDT on Jun 8, 2013

thanks for sharing

4:59AM PDT on Jun 7, 2013


4:16AM PDT on Jun 6, 2013

Thank you :)

7:58PM PDT on Jun 4, 2013

Thank you!.

I had no idea about the source of cinnamon and the coumarin content of the 2 species. Then the oxalates.

Thank you again Dr. Greger for presenting and compiling these studies for us.

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people are talking

Yes, I do: vegan and mostly raw :)

Thank you for this very informative article.

Interesting perspective.

Interesting information; thanks for sharing.


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