Common Names
- Bitter gourd; Bitter apple; wild cucumber; bitter cucumber
- balsam apple; balsam pear; margose
- la-kwa; leprosy gourd; karela; kugua; cerasee
For Patients & Caregivers
How It Works
Bitter melon has been shown to lower blood sugar levels.
Several active substances in bitter melon have been studied in both animals and humans. They act in the same way as insulin, by increasing the entry of glucose into cells and promoting its processing and storage in the liver, muscle, and fat. Bitter melon also prevents the conversion of stored nutrients to glucose and the release of this glucose into the blood. However, researchers have not established the dosage for lowering high blood glucose levels in diabetes. Therefore it cannot be recommended as a replacement therapy for insulin or hypoglycemic drugs.
Bitter melon extracts were shown to kill leukemia cells in the laboratory and slow the growth of breast cancer in mice, but it is unknown whether these effects occur in humans. A study in humans showed bitter melon had no effect on the immune system of cervical cancer patients.
Purported Uses
- To prevent cancer Laboratory studies show that bitter melon extracts can kill certain cancer cells, but it has not been studied in cancer patients.
- To treat type 2 diabetes Small clinical trials show that bitter melon extracts can lower blood glucose levels, but larger and better-designed clinical trials are needed to fully support this use.
- To reduce fever There is no evidence to support this claim.
- To treat HIV and AIDS Preliminary laboratory studies show that bitter melon can slow the ability of HIV to insert its genes into human chromosomes.
- To treat infections Bitter melon extracts can kill certain viruses on contact in the laboratory, but human data are lacking.
- To relieve menstrual problems There is no evidence to support this claim.
Do Not Take If
- You are pregnant (Bitter melon can cause vaginal bleeding, premature contractions, and abortion).
- You are taking insulin (Bitter melon may have additive effects).
- You are taking hypoglycemic medication for diabetes (Bitter melon may have additive effects).
- You are taking P-glycoprotein substrates: Bitter melon inhibits P-glycoprotein and can increase the interacellular concentration and toxicity of substrate drugs. Clinical significance is not known.
- You are taking Cytochrome P450 substrates: Bitter melon extract inhibits CYP2C9 and may affect the metabolism of substrate drugs. Clinical significance has yet to be determined.
Side Effects
- Low blood sugar
- Liver damage (this has been shown in animals, but not in humans)
- Ingestion of the seeds of bitter melon can cause toxicity to red blood cells, which includes headache, fever, abdominal pain, and coma.
- A 22-year-old man experienced atrial fibrillation (rapid irregular heartbeat) following ingestion of bitter melon two days before his admission for his dyspeptic complaints. He ingested crushed bitter melon and drank two tablespoons of its juice three times a day, and on the morning of admission as well. His symptoms improved after administering antiarrhythmic medication.
- A 40-year-old man developed acute gastric ulceration following consumption of half a liter of concentrated homemade liquid extract of bitter melon. His symptoms included severe epigastric pain and hematemesis, which were managed with intravenous fluids, blood transfusion and intravenous rabeprazole.
- Acute interstitial nephritis due to severe acute kidney injury has been associated with the use of an Ayurvedic formulation (containing bitter melon and other herbs) in a 60-year-old male with diabetes mellitus and hypertension.
For Healthcare Professionals
Clinical Summary
Bitter melon is a perennial plant that grows in the tropical and subtropical regions of Asia, South America, East Africa, and the Caribbean. The edible fruit is used both as food and in medicine to treat diabetes, cancer, viral infections, and immune disorders. Its bitterness is attributed to the presence of alkaloids, momordicosides, and momordicines. In vitro and animal studies indicate anticancer (1) (2) (3), antiviral (4) (5) (6) and lipid lowering (7) effects.
Bitter melon was shown to lower blood sugar levels in both pre-diabetic (39) and diabetic patients (8) (40), but robust data are needed to recommend its use (9) (40). Studies also indicate that bitter melon extracts have the potential for increasing insulin sensitivity in patients with type-2 diabetes compared to those with type-1 disease (31). And supplementation was found useful in reducing pain and improving symptoms in primary knee osteoarthritis patients (41).
In a study of cervical cancer patients, bitter melon had no effect on natural killer cell activity (10).
Although bitter melon is consumed as food, ingesting the seeds, extracts, and large quantities of juice can cause adverse effects.
Mechanism of Action
In an animal model, bitter melon extract showed hypoglycemic activity by suppressing glucose-6-phosphatase and fructose-1,6-bisphosphatase enzymes in the liver (14). It improved insulin sensitivity, glucose tolerance and insulin signaling (15); it also reduced insulin resistance by influencing peroxisome proliferator-activated receptor (PPAR) alpha and PPAR gamma expression (16) and by modulating the phosphorylation status of insulin receptor and its downstream signaling molecules (17). The preventive effects of bitter melon against insulin resistance are thought to be via modulation of nuclear factor (NF-kappa B) and phospho-c-Jun N-terminal kinase (JNK) pathways (36).
Bitter melon may help weight loss by reducing lipogenesis in adipose tissue. Animals that were fed with bitter melon showed lower fatty acid synthase (18). Bitter melon also affects fat and carbohydrate metabolism by stimulating thyroid hormones and adiponectin, and by enhancing the activity of AMP-activated protein kinase (AMPK) (19). In another study, it was shown to prevent inflammation and oxidative stress, modulate mitochondrial activity, suppress apoptosis activation, and inhibit lipid accumulation during the development of fatty liver (32).
Bitter melon displays cytotoxic activity: A ribosome inhibiting protein (RIP) MCP30 has been shown to inhibit histone deacetylase-1 (HDAC-1) activity and induce apoptosis in prostate cancer cells (1). In another study, a triterpene extracted from bitter melon activated peroxisome proliferator-activated receptor (PPAR) gamma and induced apoptosis in breast cancer cells (20). Bitter melon juice also caused apoptosis by inducing caspase-3 activation through adenosine monophosphate-activated protein kinase (AMPK) in pancreatic cell lines (3). Similar effects were observed with methanol extracts which increase Bax and decrease the anti-apoptotic protein Bcl-2 (21) (22). Other studies demonstrated reduction in metastasis via suppression of MMP-2 and MMP-9 enzymatic activities in lung adenocarcinoma CL1 cells (23). Bitter melon juice was found effective in decreasing phosphorylation of the protein kinases Akt and ERK1/2, and viability of gemcitabine-resistant pancreatic cancer cells (37). MAP30, a ribosome inhibiting protein (RIP) isolated from bitter melon seeds, inhibited HIV-1 integrase and inactive DNA topology (24), leading to poor viral DNA integration (25) .
Contraindications
Adverse Reactions
- Hypoglycemia and hepatotoxicity were reported in animal studies (27).
- Toxicity: Ingestion of vicine (seed) may cause favism characterized by headache, fever, abdominal pain, and coma (38).
- Case Reports
- A 22-year-old man experienced atrial fibrillation with rapid ventricular response following ingestion of bitter melon two days before his admission for his dyspeptic complaints. He ingested crushed bitter melon and drank two tablespoons of its juice three times a day, and on the morning of admission as well. His symptoms improved after administering antiarrhythmic medication (28).
- A 40-year-old man developed acute gastric ulceration following consumption of half a liter of concentrated homemade liquid extract of bitter melon. His symptoms included severe epigastric pain and hematemesis, which were managed with intravenous fluids, blood transfusion and intravenous rabeprazole (29).
- Gastrointestinal problems have been reported with use of bitter melon (19).
- Bitter melon may cause a non-allergic type-I like hypersensitivity reaction (33).
- Acute interstitial nephritis due to severe acute kidney injury has been associated with the use of an Ayurvedic formulation (containing bitter melon and other herbs) in a 60-year-old male with diabetes mellitus and hypertension (42).
Herb-Drug Interactions
- P-glycoprotein substrates: Bitter melon inhibits P-glycoprotein and can increase the interacellular concentration and toxicity of substrate drugs, including vinblastine and paclitaxel (11) (12). Clinical significance has yet to be determined.
- Cytochrome P450 substrates: Bitter melon extract inhibits CYP2C9 and may affect the metabolism of substrate drugs (30). Clinical significance has yet to be determined.
- Insulin: Bitter melon may have an additive effect when used concomitantly (8).
- Hypoglycemics: Bitter melon may have additive effects when used concomitantly (8) (34).
- Chemotherapy: Bitter melon extracts may increase bioavailability and efficacy of certain chemo agents, in vitro (35). Clinical significance has yet to be determined.