Corosolic acid, a triterpenoid compound found in the leaves of Lagerstroemia speciosa (banaba) and other plants, has attracted scientific interest for its potential effects on metabolic syndrome, primarily due to its purported glucose-lowering and insulin-sensitizing properties. Several in vitro and animal studies suggest that corosolic acid may enhance cellular glucose uptake, modulate lipid metabolism, and reduce inflammation—all relevant to metabolic syndrome. Some small-scale human trials have reported modest reductions in blood glucose and improvements in certain metabolic parameters, but these studies are typically short in duration, use small sample sizes, and often lack rigorous controls.

A 2006 review (Stohs et al.) concluded that while preliminary data are promising, there is insufficient high-quality clinical evidence to support routine use of corosolic acid for metabolic syndrome. Most available studies focus on glucose control in type 2 diabetes rather than the full spectrum of metabolic syndrome (which also includes dyslipidemia, hypertension, and central obesity).

In summary, while there is scientific rationale and limited early evidence supporting the use of corosolic acid for aspects of metabolic syndrome, the overall quality and quantity of clinical data are low. Larger, well-designed human studies are needed before firm conclusions or recommendations can be made.