Banaba leaf extract is widely popular as an antidiabetic supplement, and its proponents claim it can help with weight loss. Does the science back them up? Read on to find out.
What is Banaba Leaf?
Lagerstroemia speciosa, commonly known as banaba, is a tropical tree widely grown in the Philippines. Traditional practitioners (and people looking for natural complements to their health management strategies) use it as antidiabetic .
Water and methanol (alcohol) extracts of this tree’s leaves are sold in capsule form and used to help lower blood sugar levels and promote weight loss. The capsules often contain other substances such as green tea, green coffee, tamarind, gymnema, black pepper, and/or metals like vanadium and magnesium .
Components and Mechanisms
Banaba leaf extract’s active components include corosolic acid, lagerstroemin, and gallotannins .
- Activating cells in the body to take up higher amounts of glucose
- Discouraging the body from breaking down starches or sucrose into glucose molecules
- Preventing the body from making glucose for energy from non-carbohydrates (opposes gluconeogenesis)
Banaba contains ellagitannins, a type of molecule present in many common fruits and nuts such as pomegranates, strawberries, and almonds .
Ellagitannins like lagistroemin may increase glucose transport activity by activating glucose transporters (GLUTs) and promoting the production of more signaling (transmission) molecules. Transmission molecules like Nf-kB and MAPK, along with GLUTs, all help cells to absorb glucose and use it for energy [3, 7].
PGG, one of the banaba’s key gallotannins, discouraged fat cell production (adipogenesis) in cell studies. Gallotannins are a type of tannic acid, the class of compound, found in red wine, which reduced blood sugar in diabetic patients. These mechanisms have led some researchers to call for deeper investigations into banaba’s antidiabetic potential .
Banaba is best studied in the context of diabetes and insulin resistance. That being said, banaba supplements have not been approved by the FDA for medical use and generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective.
Speak with your doctor before supplementing, and never use banaba in place of a prescribed medication or recommendation from a medical professional.
1) Blood Sugar Control
Banaba leaf may help lower blood sugar by increasing glucose tolerance. It can decrease glucose production in the body by up to 30% and decrease the breakdown of storage molecules (like starch and glucagon) into glucose .
Unlike many antidiabetics, banaba has not been observed to promote weight gain .
In a year-long study, 15 diabetic patients took 100 mg of pure water-soluble banaba extract pills daily. At both 6 months and 1 year, the patients had significantly improved glucose tolerance. At the end of the year, they had up to a 16% decrease in their blood sugar levels but did not have low blood sugar (hypoglycemia) .
In another clinical trial, 24 patients with mild type 2 diabetes were given 3 tablets containing a mix of banaba, green tea, green coffee, and garcinia (tamarind) 3 times a day. The patients had an average blood glucose decrease of 13.5% .
In another 2-week study of 10 type 2 diabetic patients, the subjects took 32 mg or 48 mg banaba capsules (with a 1% concentration of corosolic acid) daily. At the end of the clinical trial, they had a 30% decrease in blood glucose levels .
Despite these promising results, the FDA has not approved banaba for lowering blood glucose. In order for it to reach the rigorous standards required for approval, large-scale clinical trials must be conducted to identify a safe and effective dose. Talk to your doctor before supplementing.
People with prediabetic insulin resistance may also benefit from banaba. In one clinical trial of 80 prediabetic adults, banaba extract improved insulin sensitivity and preserved pancreatic beta-cell function over 12 weeks. However, banaba did not reduce the degree to which blood sugar spiked after a meal. Further clinical trials are needed to determine how useful banaba might be in controlling insulin resistance and preventing progression into diabetes .
2) Weight Management
A common side effect of diabetes is weight gain, and unfortunately, many antidiabetic drugs prescribed to decrease blood sugar also seem to promote fat deposition. Banaba leaf, by contrast, has not been shown to increase weight gain.
Some researchers have suggested that banaba may prevent glucose storage molecules (like starch and glucagon) from breaking down. In combination with green coffee bean extract and vitamin D3, banaba improved markers of body composition (fat mass and fat-free mass) in 30 volunteers with diabetes [9, 3].
In a 60-day pilot study involving 30 participants, tablets containing a mixture of banaba, green coffee bean, vitamin D3, and Moringa oleifera leaf (horseradish) lowered body fat levels compared to placebo .
Again, while these results are considered promising, banaba should never be used in place of what your doctor prescribes.
Other Potential Benefits
No valid clinical evidence supports the use of banaba for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts.
The studies listed below should not be interpreted as supportive of any health benefit, as they have never been repeated in humans. Talk to your doctor before taking banaba supplements.
3) Antioxidant Activity
In diabetic mice, banaba extract helped increase levels of catalase, an antioxidant enzyme in the body. Catalase helps neutralize hydrogen peroxide (H2O2), a harmful, reactive oxygen compound [14, 12].
4) Heart Health
Banaba leaf extract contains gallotannins, which are a subclass of tannic acid. Tannic acid, a component of banaba, inhibits the production of endothelin-1, a protein that is heavily involved in heart disease .
A treatment of 0.072% corosolic acid, a major component in banaba, significantly lowered blood pressure in hypertensive rats .
These effects have yet to be investigated in humans.
5) Liver Disease
Nonalcoholic steatohepatitis is a liver disease that causes excess fat to build up in the liver. Excessive fructose (sugar) consumption is a major cause of this disease.
Again, these results are limited to animal studies and have yet to be repeated in human trials.
This activity has never been investigated in animals or humans.
Corosolic, gallic, and ellagic acid in banaba leaf extract inhibits enzymes that viruses use to take over human cells (proteases and reverse transcriptase). In cells, these acids help prevent viral infection from pathogens such as HRV-4 (Human Rhinovirus) and HIV [19, 3, 20].
The clinical usefulness of this activity is unclear, as it has never been tested in living animal models, let alone in humans.
The antibacterial activity was shown to be possibly caused by the tannins and triterpenoids (bioactive molecules) found in banaba .
Because this activity has never been observed or investigated in animal or human trials, its potential relevance to medicine is unknown.
Corosolic acid, one of the main components of banaba, is under investigation for its potential to kill isolated colon cancer cells in a laboratory setting .
Corosolic acid has also been found to inhibit 12-O-tetradecanoylphorbol-13 acetate (TPA), a compound that promotes tumor growth. Based on this result, researchers may test whether extracts or active compounds of banaba could prevent cancer development in animal models [23, 24].
Limitations and Caveats
Many benefits of banaba were derived from extensive animal studies.
Human studies are few and often use a mixture of supplements, making it hard to conclude how much of the beneficial effects were solely caused by banaba extract. This is one of the reasons why banaba has not been approved by the FDA for any reason.
Side Effects & Precautions
No adverse effects have been found in clinical trials. Contrary to the logical expectation that the blood sugar-lowering capacity of banaba would cause low blood sugar (hypoglycemia), 6 clinical trials did not lead to any such effect [1, 2].
Herbs including fenugreek, garlic, guar gum, and/or horse chestnut, (which all help lower blood sugar levels), along with diabetic medication, theoretically will have enhanced effects when taken along with banaba .
There is no safe and effective dose of banaba extract because no sufficiently powered clinical trial has been conducted to find one. We can only discuss the doses which produced a benefit in existing clinical studies.
Banaba extract is commonly provided in pill form, either as an isolated extract or as an extract combined with other components.
Various studies have used 32 to 48 mg daily of banaba extract with a 1% corosolic acid concentration in adults. However, there is no set standard, and dosage recommendations will vary depending on the product and percent composition of banaba in the pills .
Pediatric studies have not been conclusive; we therefore caution strongly against giving banaba extract to children without the recommendation and supervision of a medical professional .
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