# Keishi (Cinnamomum cassia)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/keishi
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-29
**Evidence Score:** 2 / 10
**Category:** Traditional Chinese Medicine
**Also Known As:** Cinnamomum cassia, Cinnamomi Cortex, Cassia bark, Chinese cinnamon, Cassia cinnamon, Rou Gui, Cinnamon bark, Chinese cassia, Cassia Cortex

## Overview

Keishi (Cinnamomum cassia), known in Kampo medicine as cinnamon bark, contains the bioactive compound cinnamaldehyde along with cinnamic acid and procyanidins that drive its therapeutic effects. These compounds enhance insulin receptor signaling, activate GLUT4 translocation, and modulate [vascular tone](/ingredients/condition/heart-health), supporting [blood glucose](/ingredients/condition/weight-management) regulation and endothelial health.

## Health Benefits

• Significant reduction in HbA1c levels in type 2 diabetes patients (PMID: 37262194).
• Decrease in [blood glucose](/ingredients/condition/weight-management) levels in type 2 diabetics (study mentioned, no PMID).
• Improvement in [endothelial function](/ingredients/condition/heart-health) in patients with climacteric syndrome (study mentioned, no PMID).
• Reduction in serum nonesterified fatty acids and [oxidative stress](/ingredients/condition/antioxidant) markers in KBG trials (study mentioned, no PMID).
• Potential [anti-inflammatory](/ingredients/condition/inflammation) effects via COX-2 suppression (in-vitro studies).

## Mechanism of Action

Cinnamaldehyde and A-type procyanidins in Cinnamomum cassia activate insulin receptor autophosphorylation and upregulate GLUT4 glucose transporter translocation to cell membranes, enhancing peripheral glucose uptake without increasing insulin secretion. Cinnamaldehyde also inhibits the enzyme protein tyrosine phosphatase 1B (PTP1B), which normally suppresses insulin signaling, thereby amplifying [insulin sensitivity](/ingredients/condition/weight-management). Additionally, procyanidins act as [antioxidant](/ingredients/condition/antioxidant)s and modulate endothelial nitric oxide synthase (eNOS) activity, improving nitric oxide bioavailability and vascular function relevant to climacteric-related endothelial dysfunction.

## Clinical Summary

A randomized controlled trial (PMID: 37262194) demonstrated significant reductions in HbA1c levels in type 2 diabetes patients supplementing with Cinnamomum cassia extract, supporting its role as an adjunct glycemic management tool. Additional clinical data indicate measurable decreases in fasting [blood glucose](/ingredients/condition/weight-management) in type 2 diabetic populations, though several of these studies lack published PMIDs and have variable methodological quality. Clinical evidence also suggests improvement in [endothelial function](/ingredients/condition/heart-health) in women experiencing climacteric syndrome, and reductions in serum lipid fractions have been reported, though sample sizes across studies are generally modest. Overall, the evidence is promising but warrants confirmation through larger, well-controlled trials before definitive clinical recommendations can be made.

## Nutritional Profile

Keishi (Cinnamomum cassia) bark is primarily valued for its bioactive compounds rather than conventional macronutrient content. Per 100g dried bark: carbohydrates ~80g (predominantly dietary fiber ~53g, with small amounts of starch and sugars), protein ~4g, fat ~1.2g, moisture ~10g, ash ~3.5g. Key micronutrients include manganese (~17.5mg/100g, 875% DV), calcium (~1002mg/100g), iron (~8.3mg/100g), potassium (~431mg/100g), magnesium (~60mg/100g), phosphorus (~64mg/100g), zinc (~1.8mg/100g), and vitamin K (~31.2mcg/100g). Primary bioactive compounds: (1) Cinnamaldehyde (trans-cinnamaldehyde): the dominant volatile constituent at 55–90% of essential oil content (~1–4% of dry bark weight), responsible for characteristic aroma and primary pharmacological activity; (2) Coumarin: present at relatively high concentrations in C. cassia (~0.45–6.97mg/g dry weight, significantly higher than Ceylon cinnamon), a key differentiator and safety consideration with an EFSA TDI of 0.1mg/kg body weight/day; (3) Cinnamyl acetate: ~3–8% of essential oil; (4) Type-A procyanidins (oligomeric proanthocyanidins): ~1–3% dry weight, implicated in insulin-potentiating activity via insulin receptor phosphorylation; (5) Cinnamic acid and derivatives: present at ~0.1–0.5% dry weight; (6) Eugenol: minor component ~1–5% of essential oil; (7) Polyphenols (total): ~8,000–12,000mg gallic acid equivalents/100g dry weight; (8) Methylhydroxychalcone polymer (MHCP): bioactive polyphenol that mimics insulin action. Bioavailability notes: cinnamaldehyde undergoes rapid first-pass [metabolism](/ingredients/condition/weight-management) to cinnamic acid; fat-soluble compounds (coumarin, cinnamaldehyde) have enhanced absorption with food; water-soluble polyphenolic fractions (type-A procyanidins) are the primary insulin-sensitizing agents in aqueous extracts; coumarin bioavailability is high (~72%) raising hepatotoxicity concerns at supplemental doses. Essential oil yield from bark: approximately 1–2% by steam distillation.

## Dosage & Preparation

Clinically studied doses include 1000 mg of C. cassia three times daily (3 g/day total) and KBG formulations with a 7.5 g/day total dose. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Cinnamomum cassia contains coumarin at concentrations that may pose hepatotoxic risk with prolonged high-dose use, distinguishing it from the lower-coumarin Ceylon cinnamon (C. verum); the European Food Safety Authority advises a tolerable daily intake of 0.1 mg/kg body weight for coumarin. Keishi can potentiate the effects of antidiabetic medications including metformin and insulin, increasing hypoglycemia risk, and caution is warranted with anticoagulants such as warfarin due to potential additive antiplatelet activity from cinnamaldehyde. Use during pregnancy is not recommended at therapeutic doses, as high amounts of cassia may stimulate uterine contractions, and individuals with liver disease should avoid supplementation due to coumarin load. Drug interactions with CYP450-metabolized medications are possible, as cinnamaldehyde has demonstrated in vitro modulation of CYP2C9 and CYP3A4 enzymes.

## Scientific Research

Clinical trials have shown that C. cassia can reduce HbA1c levels and improve [endothelial function](/ingredients/condition/heart-health). Key studies include a randomized trial with 18 diabetic patients (PMID: 37262194) and trials involving Keishibukuryogan.

## Historical & Cultural Context

Keishi has been traditionally used in Kampo, a Japanese medical system, for treating fever, [inflammation](/ingredients/condition/inflammation), and various gynecological conditions such as hypermenorrhea and dysmenorrhea.

## Synergistic Combinations

Ginger, turmeric, ginseng, licorice, green tea

## Frequently Asked Questions

### Does Keishi lower blood sugar in type 2 diabetes?

Clinical evidence, including a randomized controlled trial (PMID: 37262194), shows that Cinnamomum cassia supplementation significantly reduces HbA1c levels and fasting blood glucose in type 2 diabetes patients. The mechanism involves cinnamaldehyde-driven GLUT4 upregulation and PTP1B inhibition, which enhance insulin sensitivity without directly stimulating insulin secretion. It is best used as an adjunct to, not a replacement for, standard antidiabetic therapy.

### What is the difference between Keishi and Ceylon cinnamon?

Keishi is derived from Cinnamomum cassia (Chinese or cassia cinnamon), while Ceylon cinnamon comes from Cinnamomum verum; the key practical difference is coumarin content. Cassia contains significantly higher coumarin levels (up to 1–12 mg per gram) compared to Ceylon cinnamon (0.017 mg per gram), meaning long-term high-dose use of Keishi carries a greater hepatotoxicity risk. Both share cinnamaldehyde as a primary bioactive, but Ceylon cinnamon is generally considered safer for extended supplementation.

### What is the recommended dosage of Keishi supplement?

Clinical studies on Cinnamomum cassia for glycemic control have most commonly used doses ranging from 1 to 6 grams of dried bark powder per day, with some standardized extracts dosed at 250–500 mg twice daily. In Kampo formulations, Keishi is rarely used in isolation and is typically combined with other herbs such as in Keishi-bukuryo-gan. Due to coumarin content in cassia, daily intake should account for the European EFSA tolerable limit of 0.1 mg coumarin per kilogram of body weight to minimize hepatotoxic risk.

### Can Keishi improve symptoms of climacteric syndrome?

Clinical data suggest that Keishi-containing formulations can improve endothelial function in women with climacteric syndrome, likely through cinnamaldehyde's upregulation of eNOS activity and subsequent nitric oxide production, which enhances vasodilation. These vascular benefits may address hot flush-related circulatory dysregulation, a key symptom cluster in perimenopause. However, the supporting studies currently lack published PMIDs, and evidence strength is considered preliminary, necessitating larger controlled trials for confirmation.

### Is Keishi safe to take with blood thinners like warfarin?

Keishi should be used cautiously alongside anticoagulants such as warfarin because cinnamaldehyde exhibits antiplatelet properties that may additively increase bleeding risk. Coumarin naturally present in Cinnamomum cassia also has mild anticoagulant potential, compounding the interaction risk when combined with warfarin or other anticoagulants like aspirin or clopidogrel. Patients on anticoagulant therapy should consult a healthcare provider before using Keishi supplements, and INR monitoring may need to be more frequent if use is initiated.

### What is the most bioavailable form of Keishi supplement?

Keishi supplements are available as standardized extracts, powders, and capsules, with standardized extracts typically offering more consistent cassia cinnamaldehyde content and potentially better absorption than whole bark powder. Studies demonstrating HbA1c reductions in type 2 diabetes have primarily used aqueous extracts or standardized formulations, suggesting these forms may deliver superior bioavailability. The extraction method and standardization level significantly influence the active compound concentration available for absorption.

### Who should avoid taking Keishi supplements?

Individuals taking anticoagulant medications like warfarin should avoid Keishi due to potential bleeding interactions, and those with liver disease or scheduled for surgery should consult healthcare providers before use. Pregnant and nursing women should avoid Keishi supplementation as safety data in these populations is limited. People with cinnamon allergies or sensitivities should not use this ingredient.

### How strong is the clinical evidence for Keishi's metabolic benefits?

Clinical evidence shows promising results, including documented HbA1c reductions in type 2 diabetes patients (PMID: 37262194) and decreases in blood glucose levels, though the overall evidence base remains moderate in size. Studies also indicate improvements in endothelial function for climacteric syndrome and reductions in oxidative stress markers, supporting multiple metabolic pathways. However, larger, longer-duration randomized controlled trials are needed to establish optimal dosing and long-term efficacy for routine clinical recommendation.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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