freshly ground cinnamon

Health Benefits of Cinnamon May Be Trumped By Liver Toxicity

[toc]Is cinnamon bad for you? To even propose that question is sacrilegious according to many sources. They tout the laundry list of benefits associated with this spice which yes, seems impressive.

The following ten advantages have not been conclusively proven in human clinical trials, but research has suggested them as being a strong possibility.

Cinnamon benefits

1. Lowers blood sugar

Using a daily dose of 1 to 6 grams (1 tsp = 2.6 grams), ground cinnamon has been found to help lower blood sugar in several studies.

It reportedly acts as a natural alpha glucosidase inhibitor – interfering with an enzyme responsible for breaking down carbs in the digestive tract (1) (2).

But more impressive is cinnamon’s methylhydroxychalcone polymer (MHCP). It’s a naturally occurring compound believed to mimic insulin.

diabetic testing blood sugarIt has been said that cinnamon is good for diabetics (as well as non-diabetics) because it may improve insulin sensitivity (3) (4).

Not only are the effects said to be immediate, but they appear to be sustained for up to 12 hours after eating cinnamon (5).

However, the toxicity side effects and symptoms associated with long term doses of that much cassia cinnamon may be disastrous for you (keep reading and you will understand why).

It’s also worth noting much of this excitement started after a 2003 study and since then, opinions have differed.

A review published in 2012 looked at 10 prior clinical trials, but not all were focused on real-time blood sugar measurements (some were for HbA1c). The review cited concerns about how the studies were designed and said there was “insufficient evidence” of using cinnamon for type 1 or type 2 diabetes (6).

However another systematic review of randomized controlled trials – published the following year – concluded that cinnamon significantly decreased fasting plasma glucose (-24.59 mg/dl) (7).

So who are we to believe?

Here is a summary of 6 clinical trials which looked at fasting blood glucose (8).

Study Type Length Cinnamon Type & Daily Dosage Fasting Plasma Glucose (normal blood sugar)
Baseline (mean ± SD) After (mean ± SD)
Khan et al Single-blind RCT 40 days Cassia powder 1 g/3 g/6 g Placebo 13.77 ± 1.33 13.97 ± 1.23
Cinnamon 12.0 ± 1.43 9.1 ± 1.40
Mang et al Double- blind RCT 40 days Cassia aqueous extract 3 g Placebo 8.66 ± 1.47 8.31 ± 1.62
Cinnamon 9.26 ± 2.26 8.15 ± 1.65
Vanschoonbe et al Double-blind RCT 6 weeks Cassia powder 1.5 g Placebo 8.28 ± 0.33 8.07 ± 0.36
Cinnamon 8.37 ± 0.64 7.91 ± 0.71
Blevins et al Double-blind RCT 3 months Cassia powder 1 g Placebo 8.04 8.02
Cinnamon 7.38 6.84
Akilen et al Double-blind RCT 12 weeks Cassia powder 2 g Placebo 8.77 ± 2.59 8.74 ± 3.11
Cinnamon 8.82 ± 3.45 8.04 ± 3.10
Anderson et al Randomized placebo controlled trial 2 months Cassia (CinSulin) 500 mg Placebo 8.57 ± 0.32 8.44 ± 0.34
Cinnamon 8.85 ± 0.36 8.19 ± 0.29

What you are not seeing above is HbA1c, or glycated haemoglobin, which is another telltale sign of diabetes. It gives a better picture of what your blood sugar levels have been in recent history (versus just in the moment, like a blood sugar test does).

Most of the clinical trials measured HbA1c and some only measured it. Looking at the before/after results for the HbA1c, we would agree that data is too wishy-washy to suggest cinnamon benefits it.

When it comes to effects on fasting blood glucose readings (normal blood sugar), the studies do seem to suggest a much more compelling case that a benefit is occurring. Though additional research still needs to be done to find out and lately, no one appears to be doing it.

A big drawback in all of the above studies is that they were using cassia cinnamon instead of Ceylon cinnamon. There is a big difference between the two.

Cassia contains high amounts of a known liver toxin. Ceylon does not. However because the latter variety is so expensive, hardly anyone uses it. To get the benefits safely, use the Ceylon variety. Here is the brand on Amazon we use daily.

2. Antioxidants

The amount of antioxidants in cinnamon according to its ORAC value is 131,420. That makes it one of the highest natural food sources. It trounces turmeric (127,068), dried basil (61,063), ginger (39,041), and is almost 20 times higher than garlic powder (6,665).

Out of the hundreds of foods in our database, only about a dozen rank higher on the ORAC scale.

3. Lowers blood pressure

Multiple studies could be cited, but what gives a more accurate representation is a meta-analysis that was published in a 2013 edition of Nutrition Journal (9).

The scientists behind this meta-analysis considered 93 pieces of research which were directly or indirectly related. Out of those, they chose what they considered to be the best 3, which were randomized clinical trials. 1 involved prediabetics and 2 involved diabetics. Each lasted for 12 weeks, which made them fairly comparable.

Compiling the results of those 3 studies, they concluded that cinnamon…

 “is associated with notable reduction of systolic and diastolic blood pressure”

…in prediabetics and diabetics. The pooled results calculated out to be a lowering of blood pressure equal to 5.39 on average for systolic and 2.6 for diastolic, at least temporarily while the spice was being used. The cinnamon dosage per day varied between 500 mg to 2.4 grams in the three studies (that’s about 1/5 to 1 teaspoon).

4. Lowers LDL cholesterol

syringe viles in cupDoes cinnamon lower LDL cholesterol? That’s the “bad” type of cholesterol (versus HDL which is considered good).

In one clinical trial of people with type 2 diabetes, 30 men and 30 women were divided into groups. Half were given a dosage of either 1, 3, or 6 grams of cinnamon per day. The other half received placebo.

After 40 days, LDL cholesterol decreased with all 3 dosages (7 to 27% lower). Those receiving placebo didn’t experience a change (10). Impressive, however other research has yielded inconsistent results.

5. Raises HDL cholesterol

Cinnamon’s HDL cholesterol effects may also be good for your health. Some earlier studies had suggested there was no effect – neither positive or negative – on HDL from using this spice (11).

However a more recent meta-analysis was done which compiled the results of 10 different randomized controlled trials. In total, that was 543 people who were given doses ranging 120 mg to 6 grams per day, for anywhere from 4 to 18 weeks (12).

After crunching the numbers for all those studies, the findings were that cinnamon increased HDL cholesterol 1.66 mg/dL. That may not sound like a lot, but your HDL number runs a lot lower versus your LDL. If you were at 50, that would represent more than a 3% increase – a good thing.

HDL (Good) Cholesterol Level HDL Cholesterol Category
Less than 40 mg/dL A major risk factor for heart disease
40—59 mg/dL The higher, the better
60 mg/dL and higher Considered protective against heart disease
Source: National Heart, Lung, and Blood Institute (13)

6. Antifungal, antibacterial, and antiviral properties

A study from over 20 years ago first found that the active constituent cinnamic aldehyde is toxic to many types of fungi.

bacteria and fungus in petri dishThe vapors of this oil were found in vitro to kill many types of fungi which are associated with respiratory tract infections (18).

This included Candida albicans, C. tropicalis, and C. pseudotropicalis, which are all types of candida yeast. As well as Aspergillus niger, A. nidulans, A. flavus, A. fumigatus, and Histoplasma capsulatum. While not exactly household names, they are common causes of illness.

Dental problems? Cinnamon oil was found to have a broad array of antibacterial activity against 10 different species of bacteria linked to tooth decay, cavities, and plaque (19).

While that was only an in vitro study, another was a double-blind crossover clinical study where two different types of cinnamon chewing gum were used by 15 adults (20). The results were a “significant reductions in total salivary anaerobes [bacteria]” with both types, compared to the amounts measured in their saliva before chewing the gum.

A study done in Japan set out to research plants which have been used as part of herbal medicine in India. They wanted to know if they demonstrated any benefits against HIV, in vitro (21).

Out of the 69 medicinal herbs and spices which were tested, 16 were found to demonstrate antiviral activity against HIV-1. There were 4 that that did it for both HIV-1 and HIV-2 viruses. Among all of them, the most effective against HIV-1 was said to be cassia cinnamon.

Remember though, this was just a test tube study and it does not mean the same thing happens in the human body, especially considering the fact that researchers were using concentrated amounts being directly applied to the virus. In a human’s bloodstream, the amount of cinnamon would be more like parts per million or billion.

Contrary to what some online sources report, cinnamon has NOT been studied for the COVID-19 coronavirus. It should not be used to treat, prevent, or cure the coronavirus, or any other virus for that matter.

7. Being researched for Alzheimer’s disease

tau protein tangles in Alzheimer's DiseaseSince the cause or causes of Alzheimer’s are unknown, no one can say how to prevent this devastating disease.

That being said, recent research has theorized that tau protein (not amyloid as previously believed) might be a key cause in Alzheimer’s, as tau correlates highly with the symptoms of memory loss and dementia.

In short, the higher amounts of tau protein deposits in the temporal lobe, the worse the side effects (at least according to some research) (14).

It is believed that the tau might be a cause of brain “tangles” which are a telltale sign of the disease.

First off, it’s interesting to note that based on a Swedish 6 year-long study, borderline diabetics over the age of 75 were around 70% more likely to develop Alzheimer’s and dementia, especially when there was high systolic blood pressure (15).

So if the suspected cinnamon benefits for Alzheimer’s, diabetes, and blood pressure end up being true, they might be related in some way.

Within just the last few years, cinnamaldehyde and the oxidized form of epicatechin are two compounds in the spice which have been found inhibit tau formation in vitro (meaning outside of the human body). More than one study has confirmed this (16) (17).

At least one of the studies showing the benefit used Ceylon cinnamon versus cassia cinnamon. That’s very important because of the associated dangers with cassia (as you will see below, even tiny quantities may be toxic if regularly consumed).

8. Arthritis anti-inflammatory

While this certainly does not mean the same thing will happen in humans, animal models have been used to measure the anti-inflammatory effects cinnamon has on rheumatoid arthritis. The results stated it “demonstrated prominent action” and “can be considered as a potential anti-rheumatic agent” (22).

But again, those were just animal models… rats. How about in humans?

No clinical studies show up on PubMed for this topic.

The closest is a study involving 92 people (52 years old on average) that were given an herbal ointment for their knee arthritis (23). The results stated that “It seems that using this herbal combination is clinically effective for patients suffering from knee osteoarthritis.” But this is a bad reference, since the ointment contained not just cinnamon, but also ginger, sesame oil, and mastic.

There are many people who use honey and cinnamon for arthritis symptoms, but like the other things on this list, this benefit has not been proven.

9. Non-alcoholic fatty liver disease research

Is it possible for there to be benefits of cinnamon for your liver AND dangerous side effects?

Well, the potential for this spice to harm your liver is well documented, it is not “suggested by science” or theorized. But before we talk about that, let’s discuss something that is theorized… cinnamon might actually help non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH).

stage of liver damageAs the name probably implies, fatty liver disease is when fat accumulates in the liver. This leads to abnormal liver function which can cause a whole array of health problems including insulin resistance, metabolic syndrome, and possibly even death.

For two of the most common causes – drinking alcohol and obesity – ultimately it is lifestyle choices which are to blame, to be put it bluntly. It’s not a disease that happens overnight, but rather it takes years of one or both of those lifestyles to develop.

NAFLD is another cause of fatty liver. As the name implies, this involves non-alcoholics. You can have this even if you’ve never drank a drop of booze in your entire life. According to the American Liver Foundation, as of 2016 up to 25% of Americans – including some children – have the disease (28).

While it does correlate with obesity and poor eating habits, it can occur in thin people who have none of those risk factors. It is believed to have a genetic component, since it often runs in families.

Non alcoholic steatohepatitis (NASH) is the most severe stage of NAFLD. It is a form of hepatitis, where cirrhosis causes irreversible liver damage. According to the NIH, 2 to 5% of Americans have NASH and a liver transplant is the only treatment available if the liver fails (29).

In a recent double-blind and placebo-controlled trial, 50 people who had NAFLD were given a daily dose of a placebo or two cinnamon supplement capsules which totaled 1.5 grams (that’s a little more than half a teaspoon) (30). Both groups received these for a period of 12 weeks.

The results? It was said that those receiving the cinnamon improved:

  • C-reactive protein levels, which are a sign of inflammation
  • Liver enzyme levels
  • Lipid profile (elevated blood fats)
  • Insulin resistance

10. Cancer research

It’s important to stress that while cinnamon seems to demonstrate anti-cancer properties, these findings are not from human clinical trials. They are from cell cultures (think Petri dishes) which are taking place in laboratories, not in a human body.

blood supply to tumor
Without angiogenesis, a tumor cannot get blood supply to grow. Image credit: Cancer Research UK/Wikimedia Commons

Angiogenesis – This is the process of growing new blood vessels, which tumors need in order to get nutrients, allowing them to grow and metastasize. It has been found in vitro that cinnamon extract inhibits a type of vascular endothelial growth factor (VEGF) which contributes to angiogenesis (24).

Altering cell behavior – Using three different leukemia cell lines, in vitro tests showed that over a period of 24 hours, cinnamon changed cell growth and cell cycles in a dose-dependent manner (the more cinnamon, the more they changed for the better). It was suggested this might reduce the growth of leukemia cells and induce T-cell differentiation (triggering T-cells, which fight cancer) (25). An earlier study drew a similar conclusion (26).

Antioxidant response – Using cultured human colon cells, it was found that cinnamon was a “potent activator” of what is called the Nrf2 antioxidant response. Why this is so interesting is that it is theorized that by inducing Nrf2 activity, it might help block DNA damage that leads colorectal cancer, as well as other cancers (27).

Side effects of cinnamon

cinnamon on sliced applesWith so many suspected health advantages, you probably want to go sprinkle some of this ground bark on everything you eat!

That might be a terrible idea.

You wouldn’t think that, considering how well tolerated it is. An allergy to this spice is so rare it’s practically unheard of. If you look up the list of cinnamon side effects on several leading healthcare websites, they list things like:

  • Too much may irritate the lining of your mouth and nose.
  • It may be a skin irritant when applied directly.
  • It could cause an adverse reaction when used with diabetes medicine, because when used together your blood sugar may drop too much.
  • It is advised to stop taking 2 weeks before a scheduled surgery, as it may make managing blood sugar throughout the process more difficult – because blood sugar may drop too much. This warning appears to be associated with cinnamon supplements, not the smaller amounts commonly found in food.
  • Cinnamon’s safety during pregnancy and breastfeeding is unknown, since it hasn’t been adequately studied for such.

Many of these are mild side effects or not unusual to see (unknown pregnancy safety is quite common in foods and supplements). The “bad” side effects are actually signs that there may be real underlying benefits, if used in other scenarios.

But there is one more side effect they all list… possible liver toxicity.

Why is cinnamon poisonous?

Cinnamon contains a naturally occurring compound called coumarin, which is a type of benzopyrone. It exhibits toxicity to the liver in both humans and animals. While not replicated in human studies, some animal models have demonstrated it to also be toxic to the kidneys.

tonka beans
dried tonka beans, image credit: Mecredis / Fred Benenson

The isolated coumarin molecule (C9-H6-O2) can be synthesized or extracted from tonka beans, which are native to Central and South America. Due to its sweet flavor and odor, previously it was used as an additive for both foods as well as tobacco products. In 1954, the FDA banned coumarin as a food additive after research using animal models concluded it was toxic to the liver (31).

While tonka beans, its extract, and other unnatural forms of coumarin are banned in the United States, other sources which naturally contain it are not regulated.

There are quite a few natural sources of courmarin. High concentrations are found in sweet grass (Hierochloe odorata), sweet woodruff (Galium odoratum), vanilla grass (Anthoxanthum odoratum), great mullein (Verbascum spp.). But none of these plants are used as human food.

Other countries including France and the United Kingdom do still allow for the tonka bean to be used, but its consumption is fairly rare, as it’s only found in gourmet desserts and other culinary specialties. Aside from tonka, the only other common high potency food source of coumarin is cassia cinnamon.

Max cinnamon per day?

While the United States does not regulate or provide formal guidelines on how much cinnamon you can eat in a day, other countries do.

The German government has set a tolerable daily intake (TDI) of 0.1 mg of coumarin per kg of body weight. They also say “slight exceeding of the TDI for one to two weeks can be seen as safe” (32).

A study which was unrelated to the German government’s advice measured 60 samples coming from 12 brands. It found that cassia cinnamon contains up to 1% coumarin (33).

Using that same concentration and applying it to the German TDI, a 150 lb person (68 kg) could consume a max of 6.8 mg of coumarin per day. Assuming the max 1% concentration, that would be around 680 mg of cinnamon.

teaspoon next to tablespoon
1/4 of the small spoon (teaspoon) per day might be the maximum safe amount

Since a teaspoon of cinnamon is 2.4 grams (2,400 mg) that would only be around a 1/4 teaspoon per day!

Almost all of the studies evaluating blood sugar benefits used significantly higher dosages – up to 6 grams. That’s up to 9 times higher than the TDI for a 150 lb person. Even the lower dose studies using 1,500 mg supplements calculate out to be 220% of that TDI.

Worse yet, the suggested blood sugar advantages were dose dependent. The lower doses – which may still be higher than the TDI – didn’t seem to demonstrate them as much.

How much coumarin is there in cinnamon according to the German government? Their published data says 3,000 mg (3 g) per kg of cassia, which is around 3/10th of 1%.

If you use that number instead, it would mean the 150 lb person could consume approximately 3x more cinnamon than stated above. Even with a daily 1,500 mg cinnamon supplement, that would put the person below the TDI. The higher dosages would still exceed it.

The German government also states that the highest measured levels were 10,000 mg (10 g) per kg of cinnamon, which is also around 1%.

Should you stop using it?

What happens if you eat a spoonful of cinnamon? Will you die if you eat too much?

Swallowing a spoonful once in a while will likely have no adverse effects. Eating too much at one time isn’t going to kill you, but it might not be very enjoyable!

It’s the repeated use of eating too much everyday or on a frequent basis that researchers find concerning.

Does that mean you should give up your pumpkin spice latte, pecan pie, and Cinnamon Toast Crunch cereal?

Absolutely, but for a totally different reason… their sugar content.

The truth is that the typical amounts found in food are not a concern, at least for people with healthy livers.

On that note, it is worth mentioning that the study suggesting liver benefits for people with NAFLD wasn’t very long. Since slightly higher amounts in the short term are not considered dangerous, one should not assume that the liver study means cinnamon is necessarily good for that organ.

Ceylon vs. Cassia: the safe solution

The more rare and expensive Ceylon cinnamon hardly contains any coumarin. The same aforementioned study that measured 12 brands of cassia reported:

“…true cinnamon [Ceylon] contains only a trace, about 0.004% [of coumarin]”

ceylon cinnamon jarThat’s up to 250 times less than the concentrations found in the common form, Chinese cassia/Saigon cinnamon (Cinnamomum cassia). Ceylon comes from a small evergreen tree which is native to Sri Lanka (Cinnamomum verum, syn C. zeylanicum). Today, it is also grown in Madagascar and the Seychelles.

Almost all human studies used cassia, since that is by far the most common form. In fact, you could look in the spice aisle of a major grocery store and you may not even find a bottle of Ceylon for sale.

Even though the human blood sugar clinical studies all used cassia, there have been studies which found that Ceylon caused significant reductions of fasting blood sugar levels and HbA1c in animals (34). Some limited human research has suggested it may not be as effective at benefiting blood sugar as cassia, but no clinical trials have been done.

Where to buy Ceylon?

If you’ve never had it before, it tastes like cassia albeit much milder. The flavor is not as sharp. As a result, eating larger quantities is much more enjoyable.

The drawback is that buying a bottle isn’t always affordable. Plus, as is the case with anything expensive, counterfeit or fake cinnamon masquerading as Ceylon is a possibility to consider. Presumably, it’s feasible an unscrupulous supplier could dilute cassia with a filler to make the flavor more mild and hence, try to pass it off as Ceylon.

To be clear, we aren’t aware of any recent stories of that occurring, but it is a concern that has been brought up.

We at Superfoodly prefer to buy our Ceylon in larger quantities online to save money. Brands we trust and use include:

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.