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Corosolic acid is the compound that gives banaba leaf its reputation as a “blood sugar herb”. It is sold on its own and in weight-loss, metabolism and even memory formulas, sometimes marketed as “plant insulin”. So what are the real corosolic acid benefits?
We searched PubMed and read the human studies on corosolic acid and banaba leaf, the main reviews and a published kidney-injury case report. Here is what it may help with, what it has not been shown to do, the doses studied and who should avoid it.
Corosolic Acid in Short
Corosolic acid is a natural plant compound (a triterpene) found in banaba leaves (Lagerstroemia speciosa). In a few small human studies, corosolic acid or banaba extract lowered blood sugar, mainly after a sugary drink or meal. The trials were small and short, and several tested banaba mixed with other ingredients. There are no human studies on memory, and no good weight-loss trial of corosolic acid alone. It may add to the effect of diabetes medicines, and one case report linked it to kidney injury.
What Is Corosolic Acid?
Corosolic acid is a pentacyclic triterpene, a type of plant compound related to ursolic acid. Its best-known source is the leaf of the banaba tree (Lagerstroemia speciosa), long used in folk medicine for diabetes. A 2012 review notes that the first published banaba research appeared in 1940.
Supplements come in three main forms: whole banaba leaf extract, banaba extract standardised to 1% corosolic acid (sold under names such as Glucosol), and purified corosolic acid. Banaba’s blood-sugar effects are thought to come from both corosolic acid and compounds called ellagitannins. Lab and animal studies suggest it may help cells take up glucose, slow starch and sugar breakdown in the gut, and reduce glucose production in the liver.
Corosolic Acid Benefits: What the Research Says
Here are the human studies we could verify on PubMed. Note how small they are, and that several tested banaba combined with other ingredients.
| Study | Who and what | Main result |
|---|---|---|
| Judy et al., 2003 | People with type 2 diabetes, banaba extract with 1% corosolic acid (Glucosol), 32 or 48 mg/day for 2 weeks | Significant drop in blood glucose; about 30% with a soft-gel capsule vs 20% with a dry-powder capsule |
| Fukushima et al., 2006 | 31 adults (19 with diabetes), single 10 mg dose of corosolic acid or placebo before a glucose drink | Lower blood sugar from 60 minutes; significant only at 90 minutes |
| López-Murillo et al., 2022 | 24 adults with metabolic syndrome, banaba 500 mg twice daily or placebo for 12 weeks (12 per group) | Small drops in fasting glucose, triglycerides and blood pressure; 8 of 12 no longer had metabolic syndrome |
| Battipaglia et al., 2025 | 31 overweight postmenopausal women, banaba 48 mg (1% corosolic acid) plus 2 g myo-inositol for 12 weeks; no control group | Lower fasting insulin and insulin resistance (HOMA-IR); glucose curve 23.5% lower after a glucose test |
| Chong et al., 2014 | 91 overweight adults on a calorie-reduced diet, blend of garcinia, green tea, green coffee and banaba, or placebo, for 12 weeks | 2.26 kg weight loss vs 0.56 kg with placebo; effect of banaba alone unknown |
| Stohs et al., 2016 | 30 adults, banaba plus moringa, green coffee and vitamin D3 for 60 days; compared with a historical placebo group | Less fat mass and more lean mass; no adverse effects; pilot study only |
1. Blood sugar
This is the main use and has the most research. In the best-controlled study (2006), 31 adults took 10 mg of corosolic acid or a placebo five minutes before a 75 g glucose drink. Blood sugar was lower from 60 minutes onward, but the difference was statistically significant only at 90 minutes: a modest signal from a one-day test.
Longer studies used banaba extract. The 2003 Glucosol study in type 2 diabetes reported lower blood glucose after two weeks, but its abstract does not mention a placebo group. A 2022 placebo-controlled trial in 24 people with metabolic syndrome found small improvements in fasting glucose, triglycerides and blood pressure over 12 weeks. A 2025 review on prediabetes called the results “promising” but said more research is needed.
The evidence points the right way, but the trials are small and use different products and doses. None show it can replace diabetes medication, and a 2026 review describes “a critical gap” between promising lab data and robust clinical proof.
2. Weight loss
We found no good human trial of corosolic acid on its own for weight loss. Both weight studies we checked used blends: one (with garcinia, green tea and green coffee) gave about 1.7 kg more weight loss than placebo in dieters over 12 weeks; the other was a 30-person pilot without a real placebo group. The 2022 banaba trial did not report a significant change in body weight.
3. Memory and brain health
We searched PubMed for corosolic acid or banaba with memory, cognition and brain terms and found no human studies. The closest was a 2022 rat study in which corosolic acid reduced brain damage after an experimental stroke. That tells us nothing about memory or focus in people.
Yet corosolic acid now appears in some brain supplements. One example is Phytomem One, a once-a-day memory and focus tablet that lists corosolic acid (banaba) among its ten ingredients, alongside saffron, berberine and Ceylon cinnamon. It does not disclose how much corosolic acid each tablet contains. We looked at the whole formula in our Phytomem One review.
Corosolic Acid Dosage: How Much Was Studied?
| Pure corosolic acid | 10 mg as a single dose before a glucose drink (2006 trial) |
| Standardised banaba (1% corosolic acid) | 32-48 mg a day (2003 trial); 48 mg a day with myo-inositol (2025 study) |
| Banaba leaf extract | 500 mg twice daily, before breakfast and dinner (2022 trial) |
| How long | From a single dose up to 12 weeks; no long-term trials |
| Timing | Studies gave it before meals or before a glucose test |
These amounts differ a lot: 48 mg of a 1% extract holds roughly 0.5 mg of corosolic acid, while the 2006 trial used 10 mg of the pure compound. There is no agreed standard dose, so never take more than the label says.
Corosolic Acid Side Effects and Safety
The 2012 review reported no adverse effects in animal studies or controlled human trials. But those trials were small and short, so rare or long-term problems could be missed.
Two points stand out. First, low blood sugar (hypoglycaemia): combining corosolic acid with insulin, sulfonylureas or other glucose-lowering drugs could push levels too low. Second, kidney injury: a 2010 case report in the American Journal of Kidney Diseases is titled “Corosolic acid-induced acute kidney injury and lactic acidosis in a patient with impaired kidney function”. One case does not prove harm for most people, but it is a clear reason for caution if your kidneys are not working well.
Corosolic Acid Pros and Cons
👍 PROS
Human data: a placebo-controlled test showed lower blood sugar after a glucose drink.
Long history: banaba has been studied since 1940.
Small doses: studies used milligram amounts.
Well tolerated: no adverse effects reported in short trials.
👎 CONS
Tiny trials: most were small, short or had no placebo group.
Mixed products: many studies used blends, so the effect of corosolic acid alone is unclear.
No brain evidence: no human studies on memory or focus.
Safety flags: low blood sugar risk with diabetes drugs and a kidney-injury case report.
Corosolic Acid FAQ
Is corosolic acid the same as banaba?
Not exactly. Corosolic acid is one active compound in banaba leaf. Banaba extracts also contain other compounds, such as ellagitannins, and are often standardised to 1% corosolic acid.
Does corosolic acid lower blood sugar?
Small human studies suggest it can modestly lower blood sugar, especially after a sugary drink or meal. The trials were small and short, and it is not a replacement for diabetes treatment.
Does corosolic acid help with weight loss?
Not proven. The weight-loss studies we found used banaba mixed with other ingredients such as green coffee and garcinia, so the effect of corosolic acid alone is unknown.
Does corosolic acid improve memory?
There is no human evidence. We found only one rat study on brain injury after stroke, and no studies of memory or focus in people.
Can I take corosolic acid with metformin or insulin?
Only with your doctor’s approval. Corosolic acid lowers blood sugar, so taking it with diabetes medicines may increase the risk of hypoglycaemia.
Is corosolic acid safe for the kidneys?
Short trials reported no problems, but a 2010 case report linked corosolic acid to acute kidney injury and lactic acidosis in a patient with impaired kidney function. People with kidney disease should avoid it unless a doctor advises otherwise.
Scientific References
- Stohs SJ, Miller H, Kaats GR. A review of the efficacy and safety of banaba (Lagerstroemia speciosa L.) and corosolic acid. Phytother Res. 2012. PMID 22095937
- Judy WV, et al. Antidiabetic activity of a standardized extract (Glucosol) from Lagerstroemia speciosa leaves in Type II diabetics. J Ethnopharmacol. 2003. PMID 12787964
- Fukushima M, et al. Effect of corosolic acid on postchallenge plasma glucose levels. Diabetes Res Clin Pract. 2006. PMID 16549220
- López-Murillo LD, et al. Effect of banaba (Lagerstroemia speciosa) on metabolic syndrome, insulin sensitivity, and insulin secretion. J Med Food. 2022. PMID 34726501
- Battipaglia C, et al. Combined myo-inositol and banaba (1% corosolic acid) improve HOMA-IR and hepatic insulin extraction index in overweight and obese postmenopausal women. Gynecol Endocrinol. 2025. PMID 41340221
- Chong PW, et al. IQP-GC-101 reduces body weight and body fat mass: a randomized, double-blind, placebo-controlled study. Phytother Res. 2014. PMID 24797657
- Stohs SJ, Kaats GR, Preuss HG. Safety and efficacy of banaba-Moringa oleifera-green coffee bean extracts and vitamin D3 in a sustained release weight management supplement. Phytother Res. 2016. PMID 26871553
- Zheng JQ, Zheng CM, Lu KC. Corosolic acid-induced acute kidney injury and lactic acidosis in a patient with impaired kidney function. Am J Kidney Dis. 2010. PMID 20659629
- Zhang L, et al. Neuroprotective effect of corosolic acid against cerebral ischemia-reperfusion injury in experimental rats. J Oleo Sci. 2022. PMID 36089398
- Derosa G, et al. Exploring nutraceutical solutions for prediabetes: a narrative review on the effects of banaba and chromium picolinate. Eur Rev Med Pharmacol Sci. 2025. PMID 40613623
- Xu X, et al. A review of the pharmacological mechanism of corosolic acid. Front Pharmacol. 2026. PMID 41929254
Medical disclaimer: This article is for information only and is not medical advice. Statements about supplements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to your doctor before taking corosolic acid or banaba leaf, especially if you have diabetes, take blood-sugar-lowering medication, have kidney disease, or are pregnant or breastfeeding.