How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Cinnamon
Spice studied primarily in type 2 diabetics: it lowers fasting blood glucose in several meta-analyses, with a less consistent effect on glycated hemoglobin. Cassia cinnamon contains coumarin.
Benefits
- Lowers fasting blood glucose in type 2 diabetics and prediabetics, in meta-analyses of 8, 10, 16 and 24 trials; from 10.3% to 29% in two trials out of three with cassia cinnamon
- Glycated hemoglobin (HbA1c): −0.83% vs −0.37% without cinnamon, at 1 g per day for 90 days in 109 type 2 diabetics; the meta-analysis of 24 trials also sees a decrease
- Lower insulin resistance (HOMA-IR index) in meta-analyses of 16 and 24 trials
- Lower systolic and diastolic blood pressure (9 trials, 641 people), especially at 2 g per day or less and for at least 12 weeks
- Lower triglycerides and total cholesterol (13 trials, 750 people), with no effect on LDL
- Polycystic ovary syndrome: more frequent menstrual cycles at 1.5 g per day for 6 months (45 women)
Precautions
If you are taking antidiabetic medications, talk to your doctor: in the trials, cinnamon was added to usual treatments and lowered blood glucose on top of that. Cassia cinnamon contains up to 1% coumarin, and high consumption can exceed the tolerable daily intake: in 24 volunteers, the coumarin from cassia powder was absorbed almost as much as isolated coumarin (56% vs 62.8%), and even faster as an herbal tea. The most frequent side effects are digestive and allergic, most often transient; one review considers that at medicinal doses or over long periods they can become significant and require monitoring. In trial meta-analyses, they are no more frequent than under placebo; in the Ceylon cinnamon trial, 2 participants out of 30 stopped due to digestive disorders, with no liver damage or anticoagulant effect. Also worth noting: the effect on glycated hemoglobin is not consistent (nothing in the meta-analyses of 10 and 16 trials), the trials use very different preparations and doses, with high heterogeneity, and in polycystic ovary syndrome cinnamon changed neither weight nor androgens.
Recommended dosage
1 to 2 g of cinnamon per day in diabetes trials (from 120 mg to 6 g depending on the studies); 1.5 g per day in polycystic ovary syndrome.
How to take it
- For whom: almost all trials involve type 2 diabetics, prediabetics or women with polycystic ovary syndrome; only one, involving 30 adults, involves healthy people.
- Dose: 1 g per day for 3 months in two diabetes trials (109 and 140 patients), 2 g per day for 12 weeks in a third (58 patients); meta-analyses cover 120 mg to 6 g per day, over 4 to 18 weeks.
- Duration: the effect on blood pressure is more pronounced from 12 weeks onwards, and fat mass only decreases from 2 g per day for at least 12 weeks.
- Form: whole cinnamon or extract, both lower fasting blood glucose (meta-analysis of 8 trials); Ceylon cinnamon was tested as an aqueous extract of 85 to 500 mg per day in healthy adults.
- In addition to treatment: in the trial of 109 diabetics, cinnamon was added to usual care.
- What does not work: 80 mg of extract per day for 4 weeks did not eradicate Helicobacter pylori.
- Timing and meals: no study in this file compares the timing of intake or intake during a meal.
Did you know?
In 24 volunteers, the coumarin from cinnamon drunk as an herbal tea passed into the blood the fastest, and in the same amount as pure coumarin in a capsule over eight hours (66.1% vs 62.8%).
What the studies say
This updated meta-analysis, based on 24 randomized clinical trials, evaluated the effects of cinnamon supplementation on glycemic control in patients with type 2 diabetes. The results showed that cinnamon led to a statistically significant reduction in fasting blood glucose, the HOMA-IR index (a marker of insulin resistance), and hemoglobin A1C. In contrast, it did not significantly alter serum insulin levels. These conclusions suggest that cinnamon may have clinical potential as an add-on therapy for the management of type 2 diabetes.
Moridpour AH, Kavyani Z, Khosravi S, Farmani E, Daneshvar M, Musazadeh V, Faghfouri AH. — Phytotherapy research : PTR (2024) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more