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Banaba leaf extract, benefits, sugar level, diabete, medical uses - ZHION.COM
- June 23, 2011
Banaba [Lagerstroemia speciosa] has been used in Philippines to control blood sugar
level for years. Research done with its active ingredient, corosolic acid, suggests its
benefit on diabetes. However, clinical studies are needed to confirm the findings. Since
it may possibly interact with other therapeutics, users must discuss with their healthcare
providers before taking this herbal remedy.

Research
The use of banaba for diabetes in the US is relatively new and I don't see many studies
done with this herb.

Diabetes
As early as in 1996, Kakuda T and co-workers from Itoen Ltd, Japan, fed non-insulin
dependent diabetic mice with a diet containing extracts of banaba leaves. They found
that the elevation of blood plasma glucose level in non-insulin dependent diabetic mice
fed the cellulose as control diet were almost entirely suppressed by addition of the
extracts. [Biosci Biotechnol Biochem. 1996 Feb;60(2):204-8]

In another study, Corosolic acid inhibits gluconeogenesis by increasing the production
of Fructose-2,6-bisphosphate by lowering the cAMP level and inhibiting
cAMP-dependent protein kinase activity in isolated hepatocytes. Furthermore,
Corosolic acid increased glucokinase activity in isolated hepatocytes without affecting
glucose-6-phosphatase activity, suggesting the promotion of glycolysis. These effects
on hepatic glucose metabolism may underlie the various anti-diabetic actions of
Corosolic acid. [Diabetes Res Clin Pract. 2008 Apr;80(1):48-55.]

Obesity and triglyceride
An animal study indicates that banaba leaf extract may benefit people with obesity. In
this study, KK-Ay mice were fed a control diet or test diet containing 5% of a hot-water
extract from banaba leaves instead of cellulose for 12 wk. Neither group showed any
changes in diet intake during the experimental period. Body weight gain and
parametrial adipose tissue weight were lowered significantly in the banaba diet group.
Furthermore, tthe mice fed banaba extract showed a significant decrease, to 65% of
the control level in total hepatic lipid contents. This decrease was due to a reduction in
the accumulation of triglyceride. [J Nutr Sci Vitaminol (Tokyo). 1999 Dec;45(6):791-5]

One may wonder how banaba extract benefits the obese mice? The same group from
ITO EN, Ltd, Japan, found that Banaba contains valoneaic acid. The
alpha-amylase-inhibiting activities of the decoctions were dependent on the whole
valoneaic acid contents. In addition, a strong linear correlation was observed between
the whole valoneaic acid contents and total polyphenol contents. [Yakugaku Zasshi.
2003 Jul;123(7):599-605]

In 2005, a group from Korea published a report that mulberry leaf water extract, Korean
red ginseng, banaba leaf water extract, and the combination of above herbs effectively
reduced blood glucose, insulin, TG, and percent HbA1c in diabetic mice. These
extracts increased insulin sensitivity, and improve hyperglycemia possibly through
regulating PPAR-mediated lipid metabolism in the study. [Life Sci. 2005 Nov
12;77(26):3344-54. Epub 2005 Jun 23.]

Corosolic acid inhibited the mean blood cholesterol level by 32% nd the liver cholesterol
content by 46% compared with control 10 weeks after the start of dietary intake in a
type 2 diabetic mice. Corosolic acid may have some direct effects on the cholesterol
absorption process in the small intestine or/and corosolic acid may inhibit the activity of
cholesterol acyltransferase, which acts in the re-esterification of cholesterol in the small
intestine, in type 2 diabetes. [Biomed Res. 2010;31(4):213-8.]

Inflammation
Corosolic acid, a constituent of banaba leaves, has been reported to have
anti-inflammatory and hypoglycemic activities. In one study, it ameliorated hypertension,
abnormal lipid metabolism, and oxidative stress as well as the inflammatory state in rats
(fed with a high fat diet for 14 weeks). (Life Sci. 2006 Nov 25;79(26):2474-9.)