Banaba Extract (Corosolic Acid)
Banaba (Lagerstroemia speciosa) leaf extract, standardised for corosolic acid, is a botanical glucose-disposal supplement claimed to lower blood glucose and improve insulin sensitivity. Human evidence is limited to small short-term studies, so its real-world effect is uncertain.
01 Overview
Banaba leaf has traditional use for blood-sugar control, with corosolic acid (and ellagitannins) proposed as the active constituents. Small human trials report modest reductions in post-meal glucose, but studies are short, small and variable in extract standardisation.
Bodybuilders include banaba in glucose-disposal formulas taken with carbohydrate meals. Effects are best regarded as modest and provisional given the thin, low-quality evidence base.
02 Mechanism
Corosolic acid is thought to promote GLUT4 translocation and enhance insulin-stimulated glucose uptake, with additional alpha-glucosidase-inhibiting and PTP1B-modulating actions attributed to leaf constituents.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Supplement | 32–48 mg/day | Oral | Standardised for ~1-2% corosolic acid; often split with carb meals |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Lowered post-meal glucoseSmall studies suggest reduced post-prandial glucose with corosolic acid. | Modest | Observational | |
| Improved insulin sensitivityCell and animal data suggest enhanced GLUT4-mediated glucose uptake. | Preclinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Mild GI upsetOccasional stomach discomfort. | Mild | Uncommon | Anecdotal | |
| Hypoglycaemia with glucose-lowering drugsMay add to the glucose-lowering effect of insulin or antidiabetics. | Moderate | Uncommon | Observational |