banaba leaves have various medicinal properties.
May help control blood sugar levels
The antidiabetic effect of banaba leaves is one reason why they’re popular.Researchers attribute this effect to several compounds, namely corosolic acid, ellagitannins, and gallotannins.
Corosolic acid lowers blood sugar levels by increasing insulin sensitivity, enhancing glucose uptake, and inhibiting alpha-glucosidase — an enzyme that helps digest carbs. That’s why it’s claimed to have an insulin-like effect
Insulin is the hormone that regulates blood sugar levels. In people with type 2 diabetes, insulin resistance increases the demand for this hormone. However, the pancreas may not be able to meet those demands, resulting in high blood sugar levels
In one study in 31 adults, those who received a capsule containing 10 mg of corosolic acid had lower blood sugar levels for 1–2 hours after performing an oral glucose tolerance test, compared with those in a control group
In addition to corosolic acid, ellagitannins — namely lagerstroemin, flosin B, and reginin A — also improve blood sugar levels.
They promote glucose uptake by activating glucose transporter type 4 (GLUT4), a protein that transports glucose from the bloodstream into muscle and fat cells,Likewise, gallotanins seem to stimulate the transportation of glucose into cells. It’s even hypothesized that a type of gallotanin called penta-O-galloyl-glucopyranose (PGG) has higher stimulatory activity than corosolic acid and ellagitannins
While studies have found promising results on the anti-diabetic properties of banaba leaves, most have used a combination of herbs or compounds. Thus, further studies on the leaves alone are needed to better understand their blood sugar-lowering effects
Antioxidants are compounds that counteract the harmful effects of free radicals. These effects could otherwise negatively affect DNA, fat, and protein metabolism and promote disease
Furthermore, antioxidants protect your pancreas from free-radical damage — an additional antidiabetic effect
Banaba leaves can neutralize free radicals due to their high content of antioxidants like phenols and flavonoids, as well as quercetin and corosolic, gallic, and ellagic acids.
One 15-day study in rats found that 68 mg per pound (150 mg per kg) of body weight of banaba leaf extract neutralized free radicals and other reactive species while regulating levels of antioxidant enzymes
Still, human studies on the antioxidant effects of banaba leaves are lacking.
May offer anti-obesity benefits
Obesity affects about 40–45% of American adults, and it’s a risk factor for chronic disease.
Recent studies have linked banaba leaves with anti-obesity activity, as they may inhibit adipogenesis and lipogenesis — the formation of fat cells and fat molecules, respectively.
Also, polyphenols in the leaves, such as pentagalloylglucose (PGG), may prevent fat cell precursors from transforming into mature fat cells .
However, most research on this topic was conducted in test tubes, so human studies are needed.
May reduce heart disease risk factors
High blood cholesterol is a key risk factor for heart disease — the leading cause of death in America and third leading cause of mortality worldwide
Animal and human studies suggest that corosolic acid and PGG in banaba leaves may help lower blood cholesterol and triglycerides levels.
In one 10-week study in mice fed a high cholesterol diet, those treated with corosolic acid showed a 32% reduction in blood cholesterol and a 46% reduction in liver cholesterol levels, compared with a control group.
Similarly, a 10-week study in 40 adults with impaired fasting glucose found that a combination of banaba leaf and turmeric extracts reduced triglyceride levels by 35% and increased HDL (good) cholesterol levels by 14% .
While these results are promising, research on the direct effects of banaba leaves on blood cholesterol levels is still needed.