Berberine With Ceylon Cinnamon: 11 of 18 Labels Hold 200 mg or Less

Berberine with Ceylon cinnamon is one of the most common ways berberine is now sold. The pitch is synergy: two ingredients with a blood sugar reputation, one of them chosen in its “safe” form. We looked for the evidence that the pairing does more than berberine alone, and then read the labels to see how much cinnamon the capsules actually hold.

The one trial of the pair

A single placebo-controlled trial has tested berberine and cinnamon together. Published in the European Journal of Nutrition in 2025, it randomised people with type 2 diabetes in Tehran to “a divided daily dose of 1200 mg berberine and 600 mg cinnamon or placebo for 12 weeks.”

After 12 weeks, the combination group had lower fasting blood sugar (P = 0.031), HbA1c (P = 0.013) and LDL cholesterol (P = 0.039) than the placebo group. Total cholesterol, HDL and triglycerides did not differ, and nor did weight or the other measured markers.

The trial’s registry entry, NCT05570357, describes the capsule as 400 mg of berberine and 200 mg of “cinnamon extract” taken three times a day, against a maltodextrin placebo, with 44 people enrolled. It lists two arms and only two: the combination, and placebo. The abstract does not name the cinnamon species.

That design answers one question: does the pair beat a sugar pill? It cannot answer the one the product category rests on. Berberine on its own has lowered HbA1c in earlier trials, so a combination that beats placebo is what you would expect if the cinnamon did nothing at all. Showing that cinnamon adds something would need a berberine-only arm, and this trial did not have one.

What the labels hold

We searched the NIH Dietary Supplement Label Database for on-market products listing both berberine and cinnamon. There were 65, and 22 of them name Ceylon cinnamon.

Of those 22, 18 state how much cinnamon a serving contains. The amounts run from 0.2 mg to 2,200 mg:

Cinnamon per serving	Labels
200 mg or less	11
300 to 500 mg	2
600 mg or more	5
Amount not stated or hidden in a blend	4

The most frequent formula, on 4 labels, is 1,200 mg of berberine with 100 mg of Ceylon cinnamon. That matches the trial’s berberine and carries one sixth of its cinnamon. One label lists its cinnamon as 200 mcg, a thousandth of a typical 200 mg dose. Another declares a 2,200 mg “Berberine Plus Ceylon Cinnamon Proprietary Blend” without saying how it splits.

So the label that names Ceylon cinnamon most prominently often contains the least of it. In most of these products, the cinnamon is closer to a flavouring than to a trial dose.

How strong is the cinnamon evidence anyway?

Not strong, and mostly not about Ceylon.

The Cochrane review of cinnamon for diabetes pooled 10 trials and 577 participants. The cinnamon was “predominantly Cinnamomum cassia” at “a mean dose of 2 g daily.” It found the effect on fasting glucose inconclusive, no significant difference in HbA1c, and concluded: “There is insufficient evidence to support the use of cinnamon for type 1 or type 2 diabetes mellitus.”

Later meta-analyses are more positive but no cleaner. A 2013 analysis of 10 trials found fasting glucose fell by 24.59 mg/dL while HbA1c did not change significantly, with heterogeneity between 66.5% and 94.72%. A 2025 analysis of 28 trials found HbA1c fell by 0.56, again with heterogeneity of 94%, meaning the trials disagreed with each other well beyond what chance would explain.

Ceylon has its own trials now, both from Sri Lanka:

• 150 adults with raised LDL, 1,000 mg a day of a standardised extract for 12 weeks. The main target, LDL, did not fall significantly (p = 0.161). Fasting blood sugar fell 8.59 mg/dL more than on placebo (p = 0.036), most clearly in people with type 2 diabetes.
• 210 people with type 2 diabetes, 250 mg or 500 mg of extract for four months. The abstract reports that fasting glucose and HbA1c “significantly declined in the CZ extract groups compared to baseline.” A fall from baseline is not the same as a difference from placebo, and the abstract does not give the between-group result for HbA1c.

Those trials used 250 mg to 1,000 mg of a standardised extract. Most combination capsules list 200 mg or less of cinnamon, usually without saying whether it is an extract or ground bark.

The coumarin argument, at capsule doses

Ceylon is chosen for one real reason: coumarin. Cassia cinnamon contains it in quantity, around 2.23 mg per gram in one analysis, while Ceylon holds under 0.01 mg per gram. Coumarin can harm the liver, and European regulators set a tolerable daily intake of 0.1 mg per kilogram of body weight. Germany’s risk assessment institute found that heavy consumers of cassia could reach that limit.

That is a real concern for someone stirring teaspoons of supermarket cinnamon into food every day. It is a small one at capsule doses. For a 70 kg adult the limit is 7 mg of coumarin a day. By our arithmetic, 100 mg of cassia at 2.23 mg per gram supplies about 0.22 mg, roughly 3% of that limit. Coumarin in cassia varies widely between samples, so treat this as an order of magnitude, not a guarantee.

The Ceylon premium buys the most protection at the doses the trials used. It buys the least at the 100 mg that most of these capsules contain.

Is it actually Ceylon?

The label cannot tell you. A European Commission study of 104 cinnamon samples bought at EU retailers found that 66.3% “either did not fulfil quality criteria set by international standards, were not compliant with European food safety legislation, were suspicious of fraud, or could be toxic for children due to a high content of coumarin.” Substituting cassia for Ceylon, the authors added, “was not the problem most frequently detected.”

A separate review of 276 Ceylon cinnamon labels found that the one property that distinguishes it, its very low coumarin content, was rarely stated on the label at all.

What this means if you are choosing one

If you want berberine for blood sugar, the berberine dose is what the evidence is about. The protocol behind its reputation, and the combination trial, both used 1,200 to 1,500 mg a day in divided doses. Our berberine supplement guide covers what that evidence shows and what it does not.

The cinnamon in most combination capsules is too small to match the trials, from a species that has only begun to be tested, in a combination tested once without the comparison that would show it helps. If a label hides the cinnamon amount inside a proprietary blend, you cannot compare it with anything.

Berberine also interacts with several common medicines and adds to the effect of glucose-lowering drugs. If you take any prescription medicine, especially for diabetes, raise it with the person who prescribes it before starting.

This article is for general information and is not a substitute for advice from a doctor or pharmacist who knows your medical history.