Banaba is an extract made from the leaves of *Lagerstroemia speciosa*, a tree native to Southeast Asia. People take it to help keep blood sugar levels steady, usually with meals.
Corosolic acid and ellagitannins in the leaf encourage cells to take up glucose and help the body respond better to insulin. Capsules and liquids are the most common forms. Follow the label for dosing because amounts differ between products.
Be careful if you take diabetes medicine or insulin. Banaba can lower blood sugar further, so keep an eye on your levels. Stop taking it at least two weeks before any surgery. Pregnant or breastfeeding women should avoid it because safety data is lacking.