Meta-analysis availableSystematic review availableHuman trial evidenceTraditional useInteraction riskNeeds more research
Ceylon cinnamon is a warming spice studied for modest improvements in fasting glucose.
Ceylon cinnamon (Cinnamomum verum) is preferred over Cassia varieties because it contains far less coumarin, which can be hepatotoxic in high doses.
Quick answer
What it is: Ceylon cinnamon (Cinnamomum verum) is preferred over Cassia varieties because it contains far less coumarin, which can be hepatotoxic in high doses.
Evidence for Ceylon cinnamon largely stems from a combination of preclinical studies, small human trials, and some meta-analyses. It is primarily studied for its potential effects on blood glucose and lipid parameters, inflammation, and antioxidant capacity. The current grade reflects that while there are promising areas, robust clinical evidence with large, well-designed trials is still emerging.
Last reviewed · Jun 2026
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A classical ketogenic diet typically provides ~70–80% of calories from fat, ~15–20% from protein, and only ~5–10% (often 20–50 g/day) from carbohydrates. The metabolic shift to ketosis lowers blood glucose and insulin, raises ketone bodies (beta-hydroxybutyrate, acetoacetate), and is being studied for neurological and metabolic conditions. Variants include the Modified Atkins Diet (MAD), Medium-Chain Triglyceride (MCT) ketogenic diet, and the Low Glycemic Index Treatment (LGIT).
Foods to emphasize
Fatty fish (salmon, sardines, mackerel)
Pasture-raised eggs
Avocado and olives
Extra-virgin olive oil, coconut oil, MCT oil
Grass-fed meat and poultry
Full-fat dairy (butter, ghee, hard cheeses)
Nuts and seeds (macadamia, pecan, walnut, chia, flax)
Low-carb leafy greens and cruciferous vegetables
Bone broth and electrolyte-rich foods
Foods to avoid
Sugar and sweetened beverages
Grains and starches (bread, pasta, rice, cereal)
Most fruit (except small portions of berries)
Legumes and beans
Starchy vegetables (potatoes, corn, peas)
Low-fat or sweetened dairy
Vegetable seed oils (soybean, corn, sunflower) in excess
Most processed and packaged foods
Key principles
Carbohydrate intake usually 20–50 g net carbs per day
Adequate protein (~1.2–1.7 g/kg) — not high-protein
Most calories from whole-food fats
Track electrolytes (sodium, potassium, magnesium) to prevent "keto flu"
Best initiated with clinician guidance if on medications for diabetes, blood pressure, or seizures
Typical duration: Often 3–6 months minimum to assess response; medically supervised protocols (e.g. for epilepsy) may be maintained for years.
Why it may help
Prediabetes: Rapid improvements in fasting glucose and HbA1c, often reversing prediabetes within months.
Type 2 Diabetes: Significant HbA1c and fasting glucose reductions in clinical trials. Monitor diabetes medications closely to avoid hypoglycemia.
Insulin Resistance: Most direct mechanism — lowers insulin demand by minimizing carbohydrate load.
Ketogenic therapy is a medical intervention when used for seizure disorders or oncology — work with a clinician or registered dietitian experienced in ketogenic therapy. Not recommended in pregnancy, type 1 diabetes without supervision, pancreatitis, certain fatty-acid oxidation disorders, or active eating disorders.
Anti-Inflammatory Diet
A whole-foods pattern designed to lower chronic, low-grade inflammation by emphasizing omega-3s, polyphenols, fiber, and minimizing ultra-processed foods, sugar, and seed oils.
The anti-inflammatory diet is not a single protocol but a synthesis of the patterns most consistently linked to lower inflammatory markers (CRP, IL-6, TNF-alpha) in human studies — Mediterranean-style eating, oily fish, abundant polyphenols, and low intake of ultra-processed foods, refined sugar, industrial seed oils, and excessive alcohol.
Foods to emphasize
Fatty fish 2–3x/week (salmon, sardines, mackerel, herring)
Extra-virgin olive oil
Berries, cherries, and other deeply colored fruit
Dark leafy greens and cruciferous vegetables
Turmeric, ginger, and culinary herbs
Green tea
Nuts (especially walnuts) and seeds (flax, chia)
Legumes and whole grains
Dark chocolate (≥70% cocoa) in moderation
Foods to avoid
Sugar-sweetened beverages and refined sugar
Ultra-processed snacks and ready meals
Industrial seed oils used at high heat (soybean, corn, sunflower, cottonseed)
Processed and cured meats
Refined flour products
Excess alcohol
Key principles
Cook with olive oil, finish with extra-virgin olive oil
Aim for 25–35 g of fiber per day from whole foods
Eat the rainbow — color diversity ~ polyphenol diversity
Limit added sugar to <25 g/day
Typical duration: A long-term eating pattern.
Why it may help
Prediabetes: Lowers inflammatory markers linked to insulin resistance and metabolic progression.
Type 2 Diabetes: Reduces systemic inflammation that drives insulin resistance and beta-cell dysfunction.
Insulin Resistance: Reduces chronic low-grade inflammation that impairs insulin signaling.
Safe and flexible. Can be combined with Mediterranean, vegetarian, or plant-forward patterns.
Vegan Diet
A fully plant-based eating pattern that excludes all animal products — meat, fish, dairy, eggs, and honey.
A whole-food vegan diet emphasizes vegetables, fruit, legumes, whole grains, nuts, and seeds. It has been associated with improvements in body weight, blood lipids, and glycemic control, and is being studied for autoimmune and inflammatory conditions. It requires deliberate planning for vitamin B12, vitamin D, omega-3 (EPA/DHA), iodine, iron, zinc, and (sometimes) calcium.
Vegan diets can be excellent or deficient — quality depends on planning. Pregnant, breastfeeding, and growing children on vegan diets should be followed by a registered dietitian.
Cinnamaldehyde and polyphenols may improve insulin receptor sensitivity and slow gastric emptying.
How it works in more detail
Ceylon cinnamon appears to exert effects through various proposed mechanisms. Its polyphenolic compounds, such as proanthocyanidins, may contribute to antioxidant activity by scavenging free radicals and modulating antioxidant enzyme systems. Some in vitro and animal studies suggest it may influence glucose metabolism by affecting insulin signaling pathways and potentially inhibiting digestive enzymes like alpha-glucosidase. Furthermore, it has been studied for its potential to modulate inflammatory responses via pathways involving nuclear factor-kappa B (NF-κB), primarily in preclinical models.
How to use
Always consult a qualified clinician.
Editorial guidance
Suggested dosage
1–6 g/day of Ceylon cinnamon powder
Research dosage range
Typically 1-6 grams of powdered bark daily, or equivalent standardized extracts, in human studies.
Typical onset
Effects of cinnamon, particularly regarding metabolic parameters, typically require consistent, daily use over several weeks to potentially manifest. Acute effects are generally not characteristic of its reported actions.
Typical forms
powder, sticks, capsule, extract
Quality markers
For Ceylon cinnamon, it is important to look for products clearly labeled as Cinnamomum verum (Ceylon cinnamon) to distinguish it from Cassia cinnamon. Quality products may specify the origin, ideally Sri Lanka, and be tested for heavy metals and other contaminants. Organic certification can also be a marker of quality.
Medication interactions
anticoagulants (potential for increased bleeding risk)
diabetes medications (potential for additive blood sugar lowering effects)
hepatotoxic drugs (theoretical concern due to coumarin, though low in Ceylon)
Avoid if
known allergy to cinnamon
severe liver disease (with caution)
Community tips
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Suggested dosage
1–6 g/day of Ceylon cinnamon powder
General guidance — discuss specifics with a clinician.
Active medicinal compounds
Cinnamaldehyde, eugenol, trans-cinnamaldehyde, cinnamyl acetate, coumarin (in very low amounts compared to Cassia cinnamon)
Traditional use
Cinnamon has a long history of use in traditional medicine systems. In Ayurvedic medicine, it is valued for its warming properties and used to support digestion and respiratory health. Traditional Chinese Medicine (TCM) incorporates cinnamon for conditions associated with 'cold' and 'deficiency,' including digestive complaints and joint discomfort.
Safety
Safety warnings
Cassia cinnamon contains coumarin and can stress the liver. May potentiate blood-sugar-lowering medications.
Avoid if
known allergy to cinnamon
severe liver disease (with caution)
Medication interactions
anticoagulants (potential for increased bleeding risk)
diabetes medications (potential for additive blood sugar lowering effects)
hepatotoxic drugs (theoretical concern due to coumarin, though low in Ceylon)
Reported side effects
mild digestive upset
allergic reactions (rare)
General guidance — discuss specifics with a clinician.
Evidence ecosystem
Scientific literature, clinical guidance, government sources, ongoing research, traditional use, and lived experience — grouped by source type and quality.
Overall grade (D)
Evidence for Ceylon cinnamon largely stems from a combination of preclinical studies, small human trials, and some meta-analyses. It is primarily studied for its potential effects on blood glucose and lipid parameters, inflammation, and antioxidant capacity. The current grade reflects that while there are promising areas, robust clinical evidence with large, well-designed trials is still emerging.
The global prevalence of type 2 diabetes mellitus (DM2) has been rising significantly over the years. Recent studies have shown beneficial effects of cinnamon on metabolic biomarkers.
The objective of this review was to assess the effect of cinnamon supplementation on metabolic biomarkers in patients with DM2.
The Pubmed/MEDLINE, Cochrane CENTRAL, and Embase databases were searched up to November 10, 2022.
A systematic search was performed for randomized controlled trials (RCTs) evaluating the effect of cinnamon supplementation on metabolic biomarkers, in adults and the elderly with DM2, and comparing the data for a cinnamon intervention group with that for a placebo group or a control group. The main exclusion criteria were studies (1) with other types of diabetes (ie, gestational diabetes or type 1 diabetes), (2) without cinnamon consumption, (3) that did not evaluate metabolic biomarkers, or (4) in vitro and animal studies. Two researchers independently screened 924 records, eval
Moridpour AH, Kavyani Z, Khosravi S, Farmani E, Daneshvar M, Musazadeh V · Phytotherapy research : PTR · 2024
Although many randomized controlled trials (RCTs) have revealed the benefits of cinnamon on type 2 diabetes mellitus (T2DM), the effects of cinnamon supplementation on glycemic control in patients with T2DM are inconclusive. Therefore, the aim of this meta-analysis of RCTs was to assess the effects of cinnamon supplementation in managing glycemic control in patients with T2DM. Scientific international databases including Scopus, Web of Sciences, PubMed, Embase, and the Cochrane Library were searched till December 2022. For net changes in glycemic control, standard mean differences (SMDs) were calculated using random-effects models. Findings from 24 RCTs revealed that cinnamon supplementation had a statistically significant reduction in fasting blood sugar (SMD: -1.32; 95% CI: -1.77, -0.87, p < 0.001), Homeostatic Model Assessment for Insulin Resistance (SMD: -1.32; 95% CI: -1.77, -0.87, p < 0.001), and hemoglobin A1C (SMD: -0.67; 95% CI: -1.18, -0.15,
Ren X, Di Z, Zhang Z, Fu B, Wang Y, Huang C · Medicine · 2020
Chinese medicine has a unique theory and the Chinese herbal medicine treatment is based on the integral concepts and syndrome differentiation of the Traditional Chinese Medicine system. Although antibiotics remain the mainstay of SIBO treatment, various alternative or adjunctive therapies are available, including prokinetic agents, dietary interventions, probiotics, and herbal combinations. There is accumulating evidence demonstrating the antimicrobial properties of a growing number of herbs including garlic, black cumin, cloves, cinnamon, thyme, all-spices, bay leaves, mustard, and rosemary. This has prompted an interest in herbal therapy for the treatment of SIBO. Currently, there is no systematic review focusing on efficacy of CHM in the treatment of SIBO with PCOS, so our meta-analysis aims to comprehensively explore it. Meanwhile we will provide high-quality evidence to help patients, clinicians as well as health policymakers select better treatment strategy of PCOS.
We will sear
Meta-AnalysisPubMedVery High Quality
Systematic Reviews(1)
Structured reviews of the full body of evidence (incl. Cochrane).
Manouchehri A, Abbaszadeh S, Ahmadi M, Nejad FK, Bahmani M, Dastyar N · JBRA assisted reproduction · 2023 · n=15
Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects one in every 15 women worldwide. This disorder is mainly characterized by increased levels of male hormones (androgens), acne, and hirsutism, and can lead to long-term insulin resistance, miscarriage, or even infertility in women. PCOS is a disorder that can be treated with natural and allopathic remedies that work against the PCOS mechanism. The present study reviews previous studies on the treatment of PCOS using natural drugs.
The data in this study were collected from articles published in reputable databases including ScienceDirect, PubMed, Google Scholar, and SID in the field of medicinal plants from 1990 to 2021.
A review of the literature showed that plants such as aloe vera and chamomile improve fertility by increasing the number of ovarian follicles. Besides, Vitex agnus-castus and octane reduce hirsutism by reducing testosterone and androgen levels. It was also shown that liquorice, ginseng, cinnamon, a
Systematic ReviewPubMedVery High Quality
Observational Studies(3)
Cohort, case-control, and cross-sectional human studies.
Alesi S, Ee C, Moran LJ, Rao V, Mousa A · Advances in nutrition (Bethesda, Md.) · 2022
Polycystic ovary syndrome (PCOS) affects 1 in 5 women of reproductive age, and is characterized by menstrual irregularities, clinical or biochemical hyperandrogenism, and the presence of polycystic ovary morphology. One of the recommended treatment strategies in the international evidence-based guidelines is lifestyle modification, which includes diet and exercise, with the aim of improving a range of health outcomes. The incurable nature of PCOS reinforces the importance of developing novel and innovative symptomatic relief strategies, which are currently the only available approaches for improving quality of life for these women. Women with PCOS tend to be nutrient deficient in many common vitamins and minerals, thought to be associated with the psychological (depression, anxiety, etc.) and physiological (insulin resistance, diabetes, infertility, etc.) sequelae of the condition. Nutrient supplementation and the integration of complementary medicine as adjuncts to traditional lifesty
Gruenwald J, Freder J, Armbruester N · Critical reviews in food science and nutrition · 2010
Cinnamon has been used as a spice and as traditional herbal medicine for centuries. The available in vitro and animal in vivo evidence suggests that cinnamon has anti-inflammatory, antimicrobial, antioxidant, antitumor, cardiovascular, cholesterol-lowering, and immunomodulatory effects. In vitro studies have demonstrated that cinnamon may act as an insulin mimetic, to potentiate insulin activity or to stimulate cellular glucose metabolism. Furthermore, animal studies have demonstrated strong hypoglycemic properties. However, there are only very few well-controlled clinical studies, a fact that limits the conclusions that can be made about the potential health benefits of cinnamon for free-living humans. The use of cinnamon as an adjunct to the treatment of type 2 diabetes mellitus is the most promising area, but further research is needed before definitive recommendations can be made.
Bradley R, Oberg EB, Calabrese C, Standish LJ · Journal of alternative and complementary medicine (New York, N.Y.) · 2007
To develop a model to direct the prescription of nutritional and botanical medicines in the treatment of type 2 diabetes for both clinical and research purposes.
Available literature on nutritional and botanical medicines was reviewed and categorized as follows: antioxidant/anti-inflammatory; insulin sensitizer; and beta-cell protectant/insulin secretagogue. Literature describing laboratory assessment for glycemic control, insulin resistance, and beta-cell reserve was also reviewed and a clinical decision tree was developed.
Clinical algorithms were created to guide the use of nutritional and botanic medicines using validated laboratory measures of glycemic control, insulin sensitivity, and beta-cell reserve. Nutrient and botanic medicines with clinical trial research support include coenzyme Q10, carnitine, alpha-lipoic acid, N-acetylcysteine, vitamin D, vitamin C, vitamin E, chromium, vanadium, omega-3 fatty acids, cinnamon (Cinnamomum cassia), fenugreek (Trigonella foenum-graecum)
Observational StudyPubMedLow Quality
Clinical Trial Registries(4)
Registered ongoing or completed trials (ClinicalTrials.gov).
The goal of this clinical trial is to learn if a 12-week nutritional supplement can result in significant changes in the body composition of 38-55-year-old females. The main questions it aims to answer are:
* Does a 12-week nutritional supplementation with myo-inositol, berberine, cinnamon, and chromium lead to significant changes in body composition (e.g. body mass index, body fat composition) in females aged 38-55 compared to placebo?
* Does a 12-week nutritional supplementation with myo-inositol, berberine, cinnamon, and chromium lead to significant changes in small molecules (metabolites) in plasma and urine, menopause-related symptoms, and physical performance (e.g. grip strength) in females aged 38-55 compared to placebo? Researchers will compare the nutritional supplement to a placebo (a look-alike substance that contains no nutritional supplement) to see if the intervention works to change body composition in females aged 38-55.
Participants will:
* Sign a consent form before any procedures begin
* Attend two visits to the clinical research facility at Southampton General Hospital over 12 weeks.
* Fast before visit's and provide blood and urine samples at each visit
* Undergo measurements at each visit, including waist and hip circumferences, grip and leg strength, and body composition.
* Complete questionnaires about general health, menopause-related changes, alcohol consumption, physical activity, and diet.
* Take 1 capsule 3 times a day at the onset of a meal (once in the morning, once at midday, and once in the evening) for the first 10 days.
* Take 3 capsules 3 times a day at the onset of a meal (once in the morning, once at midday, and once in the evening) from day 11 to day 84.
* Record supplement intake in a daily compliance diary during the study
The purpose of this study is to ascertain whether certain supplements promote excessive urinary oxalate excretion and increase the risk for calcium oxalate kidney stones. Supplements that enhance urinary oxalate excretion, as a result of their oxalate concentration or from some other mechanism (e.g., providing substrate for oxalate biosynthesis) will be identified by the investigators.
A research study that is evaluating a low dose of an FDA approved statin medication in comparison to several commercially available over the counter dietary supplements which are marketed for cholesterol health. The study is comparing their effect on LDL cholesterol. LDL-cholesterol is low-density cholesterol and is sometimes referred to as "bad" cholesterol. Participants must live in Ohio and have a documented elevated LDL cholesterol level between 70-189mg/dL, must not currently be taking a statin or one of the dietary supplements included in the trial. Participants willing to discontinue a prohibited supplement for 4 weeks prior to enrollment will be allowed to participate. Trial participation is 4 weeks. Study medication will be provided at no charge. There will be 2 visits which include a lab draw at any Cleveland Clinic laboratory. Participants will be randomized (like a coin flip) to be in one of 8 possible groups: Rosuvastatin, Fish oil, Cinnamon, Garlic, Turmeric, Plant sterol, Red yeast rice, or placebo. The study will enroll 200 participants.
Clinical TrialClinicalTrials.govModerate Quality
Limitations: Current research is often limited by small sample sizes, heterogeneity in study designs, and varying cinnamon preparations and dosages. Many findings are derived from in vitro or animal models, which may not directly translate to human effects. There is also a need for more long-term studies to assess sustained benefits and safety.
This page is educational. Statements use phrases like "may support" and "has been studied for"because no remedy here is approved to cure, treat, or reverse any condition. Discussion happens on the ailment pages — community statistics here are derived from those reports. Always consult a qualified clinician.
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