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Banaba leaf extract is a botanical extract from the leaves of Lagerstroemia speciosa, a flowering tree of the family Lythraceae native to tropical Asia, also known as giant crepe-myrtle or pride of India. Long used as a leaf tea in Southeast Asian folk medicine for lowering blood sugar, the extract is valued for two main constituents, the triterpene corosolic acid and a group of ellagitannins. It is marketed as a dietary supplement for blood-sugar and metabolic support, with most supporting evidence coming from animal studies and small human trials.
- Supports healthy blood sugar
- Improves insulin sensitivity
- Blunts post-meal glucose spikes
- Antioxidant activity
- Can lower blood sugar, so combining it with diabetes medication may push glucose too low
- People on glucose-lowering or lipid-lowering drugs should be mindful of additive effects
Overview
Banaba leaf extract is prepared from the leaves of Lagerstroemia speciosa (L.), a tropical flowering tree in the family Lythraceae known by common names including banaba, giant crepe-myrtle, queen's crape myrtle, pride of India, and jarul [1]. The tree is native to tropical South and Southeast Asia and Melanesia, and its leaves have a long history of use in folk medicine, particularly in the Philippines, where a leaf tea has traditionally been taken to help manage blood sugar; the first published research on the plant dates to 1940 [1][2].
The leaf's activity is attributed chiefly to two kinds of compound. Corosolic acid is a pentacyclic triterpene often used to standardize commercial extracts, while a set of ellagitannins, including lagerstroemin, flosin B, and reginin A, contributes additional glucose-related effects [1][2]. Water-soluble banaba leaf extracts, corosolic-acid-standardized extracts, and the purified constituents have all been studied for their effects on glucose and lipid metabolism [2].
Most research on banaba centers on blood sugar. Reviews summarizing animal, human, and laboratory studies report that banaba extract and corosolic acid can lower blood glucose, with purified corosolic acid decreasing blood sugar within about an hour in human subjects, and that corosolic acid also shows effects on blood lipids, oxidation, and inflammation [1][2]. Mechanistic studies in animals trace these effects to several actions: corosolic acid inhibited the intestinal breakdown of sugars such as sucrose, slowing their absorption [3]; it reduced glucose production by the liver by altering the cyclic AMP signaling that drives gluconeogenesis [4]; and it lowered blood and liver cholesterol in diabetic mice, apparently by interfering with cholesterol handling in the intestine [5]. Reviewers note that no serious adverse effects have been reported in the animal studies or controlled human trials conducted to date [2].
Banaba leaf extract is sold as a dietary supplement, typically in capsules or tablets standardized to a set percentage of corosolic acid, and as a traditional leaf tea. In the Philippines the plant is among the medicinal herbs officially recognized by the health authorities [1]. It is not an approved pharmaceutical, and while the metabolic findings are encouraging, they rest largely on small studies and animal work rather than large, definitive clinical trials [2].
Mechanism
Banaba's blood-sugar effects are thought to arise from several complementary actions of its active compounds rather than a single pathway [1][2]. Corosolic acid, the best-studied constituent, appears to behave in an -like manner by promoting the cellular uptake of glucose, helping muscle and other tissues pull sugar out of the blood [1]. At the same time it slows the digestive breakdown of dietary carbohydrates: in animal studies it inhibited the intestinal enzymes that hydrolyze sucrose and starches, blunting the rise in blood sugar after a meal [3]. It also curbs the liver's own production of glucose, reducing gluconeogenesis by raising fructose-2,6-bisphosphate and lowering cyclic AMP and protein kinase A activity in liver cells [4].
Beyond glucose, corosolic acid influences fat metabolism, lowering blood and liver cholesterol in diabetic mice by interfering with cholesterol absorption and re-esterification in the intestine [5]. The ellagitannins in the leaf, such as lagerstroemin, contribute their own glucose-transport-stimulating activity, and some of these effects may be mediated through signaling factors including the PPAR family [1][2].
Together these mechanisms were said to give banaba extract a broadly antidiabetic and lipid-lowering profile in preclinical models [2]; that summary rests on a review retracted in 2013 and nothing else here supports it, so it should be read as withdrawn rather than established. The individual actions above stand on their own separate sources [1][3][4][5].
receptor fingerprint
GLUT4 glucose transporterspromotes translocation
sensitivityimproves
reduces
Alpha-glucosidaseinhibits
Dosingtypical ranges, not medical advice
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Safetyrisks and cautions, not medical advice
Generally well tolerated in studies. The main practical concern is additive blood-sugar lowering when combined with diabetes medication, which can risk hypoglycemia. Mild GI upset is possible. Long-term human safety data is limited, and pregnancy safety isn't established.
Resources
This entry is here for reference.
Research
- 2008first citedEffect of corosolic acid on gluconeogenesis in rat liver
- 2012most recentA review of the efficacy and safety of banaba (Lagerstroemia speciosa L.) and corosolic acid
- 1.A review of the efficacy and safety of banaba (Lagerstroemia speciosa L.) and corosolic acid
- 2.Management of Diabetes and Its Complications with Banaba (Lagerstroemia speciosa L.) and Corosolic Acidretractedretracted 2013 (notice 10.1155/2013/694543); PubMed does not carry the notice, so the paper still reads as clean there
- 3.Effect of corosolic acid on the hydrolysis of disaccharides
- 4.Effect of corosolic acid on gluconeogenesis in rat liver
- 5.Effect of corosolic acid on dietary hypercholesterolemia and hepatic steatosis in KK-Ay diabetic mice
5 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Does banaba actually lower blood sugar?
It has a plausible insulin-like mechanism through corosolic acid and some supportive human data, so yes, modestly. It's support, not a replacement for medication.
Will it make me lose weight?
The weight effect is weak and mostly secondary to better glucose handling. Don't buy it primarily as a fat burner.
When should I take it?
Before carbohydrate-containing meals makes the most sense given how it works on post-meal glucose.
Can I combine it with diabetes medication?
Only with clinician guidance, since the blood-sugar lowering can stack and risk going too low.
Limitations of the evidence
- Most human evidence comes from small studies, so its effects and safety are not firmly established
Adverse effects
- Can lower blood sugar, so combining it with diabetes medication may push glucose too low
- People on glucose-lowering or lipid-lowering drugs should be mindful of additive effects
Notes and cautions
- Generally well tolerated in trials, with no serious adverse effects reported in the reviewed studies
- Mild digestive upset is possible, as with many botanical extracts