Banaba Leaf
Summary
Banaba leaf extract, often standardized to corosolic acid, is sold for blood sugar. Evidence is small and short (grade D): 10 mg of corosolic acid lowered glucose during a glucose test, and 12 weeks of banaba lowered fasting glucose within the banaba group. One case linked corosolic acid to acute kidney injury in kidney disease.
Key facts
- Leaf extract of Lagerstroemia speciosa, usually standardized to corosolic acid; ellagitannins may also contribute[4]
- 10 mg corosolic acid once; 32–48 mg/day of a 1% corosolic acid extract for 2 weeks; 1,000 mg/day of banaba for 12 weeks[2][3][1]
- A published case describes corosolic acid-induced acute kidney injury and lactic acidosis in a patient with impaired kidney function[5]
- The early dose study tested the branded extract Glucosol; funding for the cited trials is not stated in PubMed[3][1][2]
- 2 graded human outcomes on this page
- October 10, 2026
How it works
ProposedCorosolic acid and ellagitannins are proposed to increase glucose uptake into cells, slow the breakdown of sugars and starches, and reduce glucose production in the liver, based mainly on laboratory and animal studies.[4]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Blood glucose during a glucose tolerance test | Improved | Grade D | Crossover RCT · n = 31 · 2006 Adults with diabetes (19), impaired glucose tolerance or normal glucose Form: Corosolic acid capsule · Dose: 10 mg once, 5 minutes before a 75 g glucose drink · Duration: Single dose per period Glucose was lower from 60 to 120 minutes after the drink and significantly lower at 90 minutes than with placebo. | 16549220 (opens PubMed)Source [2] |
| Metabolic syndrome, insulin sensitivity and insulin secretion | Mixed | Grade D | RCT · n = 24 · 2022 Adults with metabolic syndrome Form: Banaba extract · Dose: 500 mg twice daily before breakfast and dinner · Duration: 12 weeks Within the banaba group, systolic blood pressure, fasting glucose (5.9 to 5.7 mmol/L), triglycerides, VLDL and insulin output fell, and 8 of 12 had remission of metabolic syndrome; the abstract reports changes from baseline rather than a comparison with placebo. | 34726501 (opens PubMed)Source [1] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Leaf extract standardized to 1% corosolic acid | Varies[3][4] | A soft-gel formulation lowered glucose more (30%) than a dry-powder capsule (20%), suggesting better absorption.[3] | No adverse effects reported in controlled human trials, according to a 2012 review.[4] | Two-week dose study in type 2 diabetes (32–48 mg/day) |
| Purified corosolic acid | Varies[2][5] | Lowered glucose within 60–120 minutes of a single dose.[2][4] | One case report of acute kidney injury and lactic acidosis in a person with impaired kidney function.[5] | Single-dose glucose tolerance study |
| Banaba leaf extract (non-standardized) | Varies[1] | No absorption data in our sources.[1] | No adverse effects reported in the abstract.[1] | 12-week metabolic syndrome trial (1,000 mg/day) |
Studied doses
Doses studied in human trials ranged from a single 10 mg dose of corosolic acid to 1,000 mg/day of banaba extract for 12 weeks. A 2-week dose study used 32–48 mg/day of an extract standardized to 1% corosolic acid.[2][1][3]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Who should be careful
- Kidney disease
- A case report describes acute kidney injury and lactic acidosis from corosolic acid in a patient whose kidney function was already impaired.[5]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Safety
Little safety data from people.
- Controlled trials
- A 2012 review found no adverse effects reported in animal studies or controlled human trials.[4]
- Kidney case
- Corosolic acid was linked to acute kidney injury and lactic acidosis in a patient with impaired kidney function.[5]
- Long-term data
- The longest trial cited here lasted 12 weeks.[1]
How to read the label
- Label dose vs clinical doseThe 12-week trial used 500 mg of banaba twice daily; the dose study used 32–48 mg/day of an extract with 1% corosolic acid (about 0.3–0.5 mg of corosolic acid).[1][3]
- StandardizationLabels often state the corosolic acid percentage; the dose study used a 1% standardized extract.[3]
- Capsule typeIn one study, a soft-gel extract lowered glucose more than a dry-powder capsule.[3]
Cost per studied dose, without the sales pitch
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Cost per studied dose
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Frequently asked questions
Does banaba lower blood sugar?
Small studies suggest a modest effect: 10 mg of corosolic acid lowered glucose 90 minutes into a glucose test, and 12 weeks of banaba lowered fasting glucose within the banaba group.[2][1]
What is corosolic acid?
A compound in banaba leaves that extracts are standardized to; ellagitannins in the leaf may also play a role.[4]
Sources
- [1]Effect of Banaba (Lagerstroemia speciosa) on Metabolic Syndrome, Insulin Sensitivity, and Insulin Secretion.. J Med Food, 2022. RCT
- [2]Effect of corosolic acid on postchallenge plasma glucose levels.. Diabetes Res Clin Pract, 2006. crossover-RCT
- [3]Antidiabetic activity of a standardized extract (Glucosol) from Lagerstroemia speciosa leaves in Type II diabetics. A dose-dependence study.. J Ethnopharmacol, 2003. RCT
- [4]A review of the efficacy and safety of banaba (Lagerstroemia speciosa L.) and corosolic acid.. Phytother Res, 2012. review
- [5]Corosolic acid-induced acute kidney injury and lactic acidosis in a patient with impaired kidney function.. Am J Kidney Dis, 2010. observational
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every evidence row re-read against its PubMed abstract. Official sources: no NIH ODS or NCCIH fact sheet covers banaba (NCCIH Herbs at a Glance checked), so no official monograph is cited. Industry ties: the 2003 dose study tested the branded extract Glucosol; no PMC full text or funding statements for any cited trial (coi.py). Kept out: combination products (DLBS3233 with cinnamon; probiotic-vitamin D-banaba nutraceutical). Retraction, expression-of-concern, erratum and withdrawn checks on all 5 PMIDs: none flagged. Page set indexable. Independent browser review (4 parallel reviewers, every evidence row checked against its abstract and official sources on the Vercel preview) found: no issues.