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Ayurveda · Traditional Chinese medicine · Western herbalism

CinnamonCinnamomum verum (Ceylon) and Cinnamomum cassia and related species (cassia)

Two barks sold as cinnamon: Ceylon (low coumarin) and cassia (about 3 g coumarin per kg on average). No trial has tested either for a gut symptom.

Botanical name
Cinnamomum verum (Ceylon) and Cinnamomum cassia and related species (cassia)
Part used
inner bark
Also called
Sanskrit Twak, Tvak; Hindi Dalchini; pinyin Rou gui (cassia bark); Gui zhi (cassia twig) (肉桂 / 桂枝); Ceylon cinnamon, True cinnamon, Cassia, Chinese cinnamon
Used in
Ayurveda, Traditional Chinese medicine, Western herbalism
Taken for
Bloating, Gas, Cramping and pain, Loose stools and diarrhea
Sold as
ground spice, quills, tea, capsules, tincture, essential oil

What is meant by cinnamon

Cinnamon is the dried inner bark of trees in the genus Cinnamomum. Two groups matter on a label. “True” or Ceylon cinnamon (Cinnamomum verum, also written C. zeylanicum) is the species the European monograph covers. “Cassia” (Cinnamomum cassia or C. aromaticum, and related species) is the cheaper bark that dominates the spice trade and that Chinese medicine calls rou gui. The twig of cassia, gui zhi, is a separate herb in the Chinese tradition.

The two are hard to tell apart as powder. In an Italian market survey of 34 cinnamon samples, about 51 percent were cassia, 10 percent probably a blend, and only 39 percent were Ceylon cinnamon, although the word “cinnamon” strictly refers to Ceylon. Sticks differ: cassia forms a thick single roll, while a Ceylon stick is made of several thin rolled layers, resembling a cut cigar.

Cinnamon is sold as ground spice, quills, tea, capsules of powder or extract, tinctures and an essential oil. A 2013 systematic review of Ceylon cinnamon says that in traditional medicine it is considered a remedy for respiratory, digestive and gynecological ailments.

In the traditions

Ayurveda (about Ayurveda)

In Ayurveda the bark is twak, identified in the Charaka Samhita database as Cinnamomum zeylanicum. That database lists it in formulas for therapeutic emesis and purgation and gives no stand-alone disease list or taste and potency values. A 2013 systematic review of Ceylon cinnamon says traditional medicine considers cinnamon a remedy for digestive, respiratory and gynecological ailments. These are traditional attributions; we found no trial testing cinnamon for them.

Traditional Chinese medicine (about TCM)

Chinese medicine uses cassia bark as rou gui. A practitioner reference classes it as hot, acrid and sweet, entering the kidney, spleen, heart and liver channels, with actions of warming the kidney and strengthening what the texts call the Ming Men fire, and dispersing cold, warming the channels and relieving pain. The one digestive pattern it lists is abdominal pain and diarrhea from spleen and kidney yang deficiency. It is contraindicated in yin deficiency with empty heat and in large doses in pregnancy. A review of cassia calls it commonly used in traditional Chinese medicine and widely used as a spice.

Western herbalism

The European Medicines Agency (EMA) accepts Ceylon cinnamon bark (Cinnamomum verum cortex) as a traditional herbal medicine for two uses: symptomatic treatment of mild, spasmodic gastrointestinal complaints including bloating and flatulence, and symptomatic treatment of mild diarrhea. The monograph, adopted in 2011, rests exclusively on long-standing use. It does not cover cassia, which is the bark most supplements actually contain.

What the plant contains

Cinnamon bark owes its aroma and much of its activity to cinnamaldehyde, with eugenol, cinnamic acid and polyphenols in smaller amounts. Cassia contains coumarin, a flavoring compound that is toxic to the liver in sensitive people; the German Federal Institute for Risk Assessment (BfR) reports an average of about 3,000 mg of coumarin per kg of cassia, with the highest measured value 10,000 mg per kg, while Ceylon cinnamon has low levels. Laboratory and animal work reviewed for Ceylon cinnamon reports antimicrobial, anti-secretory and anti-gastric-ulcer effects. Those are lab findings and have not been replicated as symptom benefits in people.

What has been tested in people

We could find no randomized trial of cinnamon for bloating, flatulence, cramping or diarrhea, the uses in the EMA monograph. The EMA monograph is based on traditional use. The human data on the gut are small physiology and infection studies.

Two crossover trials in healthy volunteers measured gastric emptying with ultrasound after rice pudding. With 6 g of cinnamon added, emptying was slower and the blood glucose response lower (median emptying 37 percent for plain pudding versus 34.5 percent with cinnamon, P < 0.05) in 14 subjects. With 1 g or 3 g in 15 subjects, there was no significant change in gastric emptying or satiety, although 3 g lowered insulin and raised GLP-1. In Helicobacter pylori infection, a pilot trial gave 15 patients 40 mg of an alcoholic cinnamon extract twice daily for 4 weeks against placebo in 8; the breath-test values did not fall and the authors concluded it was ineffective at that dose.

The most-studied outcome is blood sugar, a metabolic question rather than a gut one. A meta-analysis of 10 trials (543 patients with type 2 diabetes; 120 mg to 6 g a day for 4 to 18 weeks) found lower fasting glucose (by 24.59 mg/dL) with considerable heterogeneity, and no significant change in HbA1c. The trials did not all name the species used, so the coumarin question below applies.

StudyDoseWhat it found
Crossover trial, 14 healthy subjects (ultrasound gastric emptying) PMID 175566926 g cinnamon with 300 g rice puddingSlower gastric emptying (median 34.5% vs 37%) and lower postprandial glucose (P < 0.05)
Crossover trial, 15 healthy subjects PMID 191582091 g or 3 g cinnamon with rice puddingNo significant change in gastric emptying or satiety; 3 g lowered insulin response and raised GLP-1
Pilot controlled trial in H. pylori infection, 15 treated vs 8 placebo PMID 1084905840 mg alcoholic cinnamon extract twice daily, 4 weeksNo reduction in breath-test counts; ineffective as a single agent
Meta-analysis of 10 trials, 543 patients with type 2 diabetes (metabolic) PMID 24019277120 mg to 6 g a day, 4 to 18 weeksFasting glucose -24.59 mg/dL; HbA1c change not significant; high heterogeneity

Doses used in trials and traditional preparations

The EMA monograph for Ceylon cinnamon bark lists, for adults, an infusion of 0.5 to 1 g of comminuted bark up to 4 times daily, a liquid extract of 0.5 to 1 ml three times daily, or a tincture of 2 to 4 ml a day. It advises consulting a practitioner if bloating-type symptoms last longer than 2 weeks and if diarrhea lasts longer than 2 days, and puts rehydration first in diarrhea. A practitioner reference for rou gui gives roughly 1 to 4.5 g in a formula. The gastric emptying trials used 1, 3 and 6 g of ground cinnamon in food, and the pylori pilot used 40 mg of an extract twice daily.

Treat these figures as a record of what was studied. Whether any amount of cinnamon suits a particular person is a question for a clinician or pharmacist who knows their history.

Safety

Ceylon cinnamon bark is listed by EMA with no known undesirable effects, contraindicated in hypersensitivity to the bark or to Peru balsam, not advised in pregnancy, breastfeeding or under age 18 for lack of data.

The main safety issue is the coumarin in cassia. The BfR sets a tolerable daily intake of 0.1 mg of coumarin per kg of body weight. An adult of 60 kg reaches it with about 2 g of cassia a day, and a 15 kg child with about 0.5 g, at average coumarin content. BfR reports that coumarin used as a drug caused liver enzyme rises or hepatitis in a small group of sensitive people over a few weeks, usually reversible, and that no such cases from eating cinnamon had been described in the literature; it notes that cinnamon supplements may contain high amounts of cassia. A risk assessment confirmed the same intake threshold and found that heavy consumers of cassia could reach it.

Drug interactions

EMA reports no interactions for Ceylon cinnamon bark. The coumarin in cassia has no documented medicine interaction in the sources we read. Because trials show cinnamon can lower fasting glucose, people on diabetes medicines are the group most often told to check with a prescriber. A practitioner reference for rou gui says it may interact with antihypertensive and cardiac medicines. These are cautions from the sources, not demonstrated mechanisms.

Prescriptions flagged alongside cinnamon

Published interaction references put these medicines next to this herb, and the quiz acts on them; a pharmacist is the person to confirm any of it:

Products in the catalog with cinnamon

These catalog entries list cinnamon or one of its preparations among their active ingredients. Each page shows the amount on the label, the trials behind it and what buyers report.

Gundry MD Total Restore 4.1 out of 5 from 9,333 ratings from Amazon · $2.33 a day ActivatedYou Morning Complete 3.9 out of 5 from 1,503 ratings from Trustpilot · $2.08 a day Snap Supplements Gut Health 4.5 out of 5 from 410 ratings from Amazon · $1.20 a day Proper The Pinks Digestion + Bloat Relief 4.3 out of 5 from 264 ratings from Amazon · $0.75 a day Soothe Naturals Soothe & Renew 4.7 out of 5 from 255 ratings from soothenaturals.co · $1.33 per day at one tablespoon; the brand says one to two Banyan Botanicals Pitta Digest 4.5 out of 5 from 199 ratings from Amazon · $0.62 per day at two tablets ($27.99 for 90 on the brand site; $29.99 on Amazon); the label allows one to two tablets once or twice a day, $0.31 to $1.24 The Republic of Tea Be Well Get Relief No. 9 Herb Tea 4.7 out of 5 from 153 ratings from Amazon · $0.42 per cup on Amazon ($15.00 for 36 bags); $0.38 for the tin and $0.37 for the refill on the brand’s site SoWell Fiber (Apple Cinnamon) 4.3 out of 5 from 48 ratings from Amazon · $2.31 a day

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The questions that come up

What is the difference between cassia and Ceylon cinnamon?

Ceylon cinnamon (Cinnamomum verum) has low coumarin; cassia contains about 3,000 mg of coumarin per kg on average, according to the German BfR. Most supermarket and many supplement cinnamons are cassia. In an Italian survey, only 39 percent of samples sold as cinnamon were Ceylon.

How much cassia reaches the coumarin limit?

BfR’s limit is 0.1 mg of coumarin per kg of body weight a day. That is about 2 g of average cassia a day for a 60 kg adult, and about 0.5 g for a 15 kg child. Going over it briefly is not seen as a health risk by BfR.

Has cinnamon been tested for bloating or diarrhea?

We could find no randomized trial for either. EMA lists both as traditional uses for Ceylon cinnamon bark, based on long-standing use only.

Does cinnamon kill H. pylori?

A pilot trial gave 15 patients 40 mg of cinnamon extract twice daily for 4 weeks and found no drop in breath-test counts. The authors concluded it was ineffective as a single agent at that dose. Laboratory studies are more positive but have not translated into a treatment.

Is cinnamon used in TCM and Ayurveda for digestion?

Yes, in different forms. Chinese medicine uses cassia bark (rou gui) for cold-pattern abdominal pain and diarrhea, and Ayurveda lists the bark as twak, which reviews associate with digestive remedies. These are attributions from the traditions, not trial results.

Sources