Have you ever heard of banaba leaf extract?
Though similar in name to the yellow fruit monkeys love, banaba is very different in its beneficial properties. This extract is widely popular for its antidiabetic effects–particularly weight loss and the lowering of blood sugar. Read on to learn more about how banaba leaf extract can help with diabetes, heart health, and much more!
What is Banaba Leaf?
Lagerstroemia speciosa, commonly known as banaba, is a tropical tree widely grown in the Philippines, famous for its antidiabetic effects .
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 key components include corosolic acid, lagerstroemia, and gallotannins 
- Activates cells in the body to take up higher amounts of glucose
- Discourages the body from breaking down starches or sucrose into glucose molecules
- Prevents the body from making glucose for energy from non-carbohydrates (opposes gluconeogenesis)
Lagerstroemia is an ellagitannin, a type of molecule that is present in many common fruits and nuts such as pomegranates, strawberries, and almonds .
Lagerstroemia increases glucose transport activity by activating glucose transporters (GLUTs) and promoting more signaling (transmission) molecules to be made. 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 key gallotannins responsible for banaba’s anti-diabetic benefits, discourages fat cell production (adipogenesis). Gallotannins are a type of tannic acid, which is the same component that also enables red wine to lower blood sugar levels .
Health Benefits of Banaba Leaf
1) Is Anti-Diabetic
Banaba leaf increases cells’ glucose tolerance and thus helps to lower high blood sugar levels. It can decrease glucose production in the body up to 30% and decreases breakdown activity of glucose storage molecules (starch and/or glucagon) .
It is unlike other antidiabetic drugs because it does not cause 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 mild type 2 diabetic patients 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 of 13.5% decrease in their blood glucose levels .
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 .
2) Promotes Weight Loss
A common side effect of diabetes is weight gain, and unfortunately, many antidiabetic drugs prescribed to decrease blood sugar do not help with fat loss. By encouraging glucose storage molecules (starch and/or glucagon) to not be broken down, banaba leaf extract optimizes the conservation of energy in the body, and thus reduces appetite [8, 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 .
3) Is an Antioxidant
Banaba leaf extract reduced superoxide levels, such as dismutase, in rats. Dismutase, if left alone, can prevent cells from functioning properly and increase bacterial survival rate at an infection site [11, 12].
4) Is Anti-Inflammatory
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 [17, 3, 18].
6) Is Antibacterial
In a bacteria study, banaba leaf extract derived from water (instead of alcohol) successfully impeded the growth of harmful bacteria such as S. aureus, B. subtilis, P.aeruginosa, and E. coli .
The antibacterial activity was shown to be possibly caused by the tannins and triterpenoids (bioactive molecules) found in banaba .
7) May Help Prevent Cancer
Corosolic acid, one of the main components of banaba, kills human colon cancer cells .
8) May Improve 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 .
9) May Help Prevent 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 for this disease.
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.
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 .
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 .
Users affected by diabetes and weight gain mainly gave positive feedback when taking banaba extract in varying frequencies.
Users also had their cravings satisfied and experienced a decreased appetite and weight loss without changing their diet.
Others noticed no difference or had a decreased appetite but no significant weight loss. One user also complained about bloating.
Additionally, another user said it prevented urinary infections.
Some users took the pills 2 to 3 times a day, while others took them up to 6 times a day during meals and snacks.
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