Bitter Melon
Scientific Name(s): Momordicacharantia L.
Common Name(s): Art pumpkin, Balsam apple, Balsam pear, Bitter cucumber, Bitter gourd, Carilla cundeamor, Cerasee, Corilla, Karela, Kor-kuly, Ku gua, Ku kua karela, Melaode sao caetano, Papailla, Para-aki, Pare, Peria, Peria La at, Salsamino, Sorossis borossieb, Soru
Medically reviewed by Drugs.com. Last updated on Jul 12, 2022.
Clinical Overview
Use
Medical literature documents numerous studies of bitter melon use, primarily for its antidiabetic activity, but results are conflicting and inconclusive. There is insufficient evidence to recommend the use of bitter melon as a therapeutic option in type 2 diabetes.
Dosing
Diabetes: Bitter melon juice has been administered for type 2 diabetes at daily doses of 50 to 100 mL; 5 g of dried fruit given 3 times/day has also been used. There is insufficient clinical evidence to substantiate these doses.
Contraindications
Patients deficient in glucose-6-phosphate dehydrogenase should avoid consumption of bitter melon preparations due to the presence of vicine in the seeds.
Pregnancy/Lactation
Avoid use. Documentation of emmenagogue and abortifacient effects exists.
Interactions
None well documented.
Adverse Reactions
Bitter melon generally causes few adverse reactions. GI effects (eg, abdominal pain, diarrhea) and headache have been reported. Case reports of hypoglycemic coma and atrial fibrillation associated with bitter melon intake exist. Bitter melon should be used with caution in patients with impaired hepatic function.
Toxicology
Toxicity resulting in death has been reported in one case report of a child ingesting the red arils around bitter melon seeds.
Scientific Family
- Cucurbitaceae
Botany
Bitter melon is a member of the Cucurbitaceae family. It is cultivated in tropical areas, including the Amazon, Africa, Asia, India, South America, and the Caribbean. The plant is a climbing, flowering, perennial vine that grows up to 5 m in height. Its fruit is cucumber-shaped with surface bumps. The leaves are simple, alternate, and 4 to 12 cm in width, with 3 to 7 separated lobes. In the Northern Hemisphere, the plant produces yellow flowers during June and July, and produces fruit September through November. The unripe fruit is white or green in color and bitter in taste. The bitterness becomes more intense as the fruit ripens. However, the pith becomes sweet and is deep red in color.Chevallier 1996, Tcheghebe 2016, USDA 2017
History
The unripe fruit is commonly consumed as a vegetable and is a culinary fruit in Asia. Extracts of various parts of bitter melon are used in traditional African medicine. Fruit extracts have been used to treat diabetes, dyslipidemia, infections, and cancer. The plant seeds, fruits, leaves, and roots have been used in traditional medicine to treat indigestion, intestinal gas, menstrual conditions, wounds, inflammation, fever, and hypertension, as well as for their laxative and emetic properties. In Guyana traditional medicine, a leaf extract tea has been used in diabetes and as an antiviral. The leaf tea has also been used topically for sores and wounds, and has been administered orally and topically for worms and parasites. The leaves have been administered orally for the treatment of leprosy, hemorrhoids, and jaundice. The leaves act as a galactogogue to promote or increase milk supply, and may be applied around the eye socket for night blindness. The leaf juice may be applied to the soles of the feet to help reduce burning sensation. In Cambodia, the leaves are considered to have antipyretic activity. The fruit has been used to treat asthma, colic, constipation, cough, gout, helminthiases, inflammation, leprosy, and ulcers. The root has been used to treat syphilis, rheumatism, boils, and septic swellings. In Uganda, an infusion of the leaf and roots is used as an abortifacient.Bauman 2016, Chevallier 1996, Cunnick 1993, Duke 1989, Tcheghebe 2016, USDA 2010
Chemistry
Chemical constituents from the whole plant, fruit, and seeds of bitter melon have been isolated and described. Bitter melon fruit contains triterpene glycosides, including the characteristic mormordin and charantin. Other triterpene glycosides (momordicosides), vitamins (eg, beta carotene, ascorbic acid, niacin, thiamin), elemental compounds (eg, iron, iodine, magnesium, sodium, calcium), and fatty acids (eg, stearic, palmitic, oleic) are also present.Duke 1989 Insulin-like compounds, or compounds exerting hypoglycemic activity, have been described.Khanna 1981, Ng 1986, Raman 1996
Bitter melon seeds and the pericarp contain the phenolics catechin and epicatechin; gallic, gentisic, and vanillic acids; and lutein, lycopene, carotenes, xanthins, momordicosides, and vicine.Duke 1989, Horax 2010 The seed essential oil contains sesquiterpenes, phenylpropanoids, and monoterpenes, including nerolidol.Braca 2008, Cunnick 1993
Uses and Pharmacology
Medical literature documents numerous animal and clinical studies of bitter melon use, primarily for its antidiabetic activity. Results of clinical trials are conflicting and inconclusive.
Antimicrobial
In vitro data
Bitter melon roots, leaves, and seeds have demonstrated antibiotic and antiviral activity in vitro, including inhibition of HIV integrase.(Basch 2003, Duke 1989, Pongthanapisith 2013) Synergism with aminoglycosides has been demonstrated in methicillin-resistant strains of Staphylococcus aureus.(Coutinho 2010) Antibacterial activity has been attributed to the nerolidol content of the essential seed oil.(Ooi 2012)
Antioxidant activity
In vitro data
Free-radical scavenging activity attributed to the phenolic content has been demonstrated in vitro.(Dong 2009, Horax 2010) In hyperammonemic rats, the oxidant-antioxidant imbalance was restored by administration of bitter melon fruit extract.(Thenmozhi 2010)
Cancer
Animal and in vitro data
Anticancer effects of bitter melon on 13 cancer lines has been documented in a review article. Several in vitro and animal studies document anticancer properties related to cell-cycle arrest, expression of serum factors associated with immunity, and apoptosis.(Boetse 2011, Coutinho 2010, Hsu 2012, Li 2012, Raina 2016, Ray 2010, Waiyaput 2012, Weng 2013)
Diabetes
Animal and in vitro data
The hypoglycemic effects of bitter melon have been established in animal studies.(Bauman 2016) Hypoglycemic activity may be related to decreased gluconeogenesis, enhanced insulin secretion, protection of islet beta-cells, and inhibition of intestinal alpha-glucosidase and glucose transport. The expression of peroxisome proliferator-activated receptors involved with metabolism may also be activated or upregulated.(Choudhary 2012, Huang 2013, Leung 2009, Wang 2017)
Clinical data
While bitter melon has traditionally been used for treatment of type 2 diabetes, medical literature documents inconsistent results and poor methodology among clinical trials evaluating its effects in diabetes.(Bauman 2016, Ching 2013, Ocvirk 2013, Ooi 2012, Patel 2012, Riszi 2013)
A Cochrane systematic review and meta-analysis concluded current evidence does not warrant the use of bitter melon in treating type 2 diabetes. The review included 4 randomized controlled trials (N=479), with treatment durations up to 3 months. There was no statistically significant difference in glycemic control with bitter melon preparations compared with placebo. There was also no change in glycemic control for participants treated with bitter melon compared with metformin or glibenclamide. No serious adverse effects were reported.(Ooi 2012)
Exercise-induced fatigue
Clinical data
The effect of bitter melon (M. charantia) on fatigue biomarkers in 10 high-intensity trained male athletes during hot summer training was explored in a 4-week uncontrolled observational pilot study. Central fatigue markers were serotonin, dopamine, and prolactin, and the peripheral markers were ammonia and uric acid. Although consumption of M. charantia extract (100 mL/dose) 6 times/day significantly increased ammonia levels "before," "during," and "immediately after" exercise relative to ammonia increases observed before supplementation, levels measured the "morning after exercise" dropped significantly (P<0.05) with supplementation and were even lower than presupplementation values (79.5 vs 90.45 mcg/dL, non-significant difference); no significant effect of M. charantia extract was observed on uric acid levels. These data suggest that a peripheral antifatigue effect of bitter melon is mediated by ammonia and not uric acid metabolism. Central antifatigue effects were demonstrated by lower serotonin levels after supplementation than before, with a significant difference seen "during exercise" (P<0.05). Similarly, prolactin levels (which increase during exercise in high-temperature settings) were lower after supplementation than before, with significant differences seen "during" (P<0.01) and "immediately after" (P<0.05) exercise. Conversely, dopamine levels were higher after supplementation than before, with significant differences observed "during exercise" (P<0.05).(Kwak 2020)
Immune system
In vitro data
Crude lectin extracted or isolated from M. charantia seed upregulated immune response in vitro,(Huang 2008, Huang 2008) while a pulp extract increased the production of hepatocyte growth factor.(Ono 2009)
Dosing
Commercially available products include juices, capsules, and teas. However, scientifically proven documentation regarding the safety, appropriate dosage, or effectiveness of most products is lacking.
Diabetes
Bitter melon juice has been administered at daily doses of 50 to 100 mL, but it may be bitter and difficult to drink; 5 g of dried fruit 3 times per day has also been used. There is insufficient clinical evidence to substantiate these doses.Basch 2003 Subcutaneous preparations of bitter melon as a vegetable insulin have also been used in older clinical studies, but safety and efficacy data are lacking.Basch 2003 Although encapsulated dry powder dosage forms may be easier to administer, the standard dose is 3 to 15 g daily, a large dose in capsule form. A standardized, encapsulated extract dose ranges from 100 to 200 mg 3 times daily.Momordica charantia 2007 A transdermal dosage form (10 mg/patch) has also been evaluated.Bhujbal 2011
Pregnancy / Lactation
Avoid use. Documentation of emmenagogue and abortifacient effects exists.Ernst 2002 Antifertility actions in animals have also been described.Basch 2003, Chang 1995
Interactions
Hypoglycemia-associated agents: An increased hypoglycemic effect with coadministered pharmaceutical agents, such as hypoglycemic medications, has been postulated due to effects observed in animal studies. In a clinical trial, chloroform/benzene karela extract (400 mg) coadministered with metformin or glibenclamide (at 50% of clinical doses) produced a greater hypoglycemic effect compared to full doses of either antidiabetic alone.(Gupta 2017, Hui 2009, Tongia 2004)
Individuals with diabetes should be advised to closely monitor blood sugar if adding bitter melon to their treatment regimen. Minor effects on cytochrome P450 enzymes and glutathione S-transferase were observed in one experiment.(Appiah-Opong 2008)
Pazopanib: Bitter melon may enhance the adverse/toxic effect of pazopanib. Specifically, the risk of pancreatitis may be increased. No action needed.(Unsal 2022)
Adverse Reactions
Bitter melon is generally well tolerated. GI effects (eg, abdominal pain, diarrhea) and headache have been reported in clinical trials.Basch 2003, Ooi 2012
Increases in liver enzymes have been observed experimentally, but without histological changes. Bitter melon should be used with caution in patients with impaired hepatic function.Basch 2003, Raman 1996
Toxicology
An acute toxicity study reviewed the effects of a bitter melon extract administered orally to rats at 2 different doses: 300 mg/kg and 2,000 mg/kg of body weight. Within 30 minutes, both treatment groups showed signs of dizziness and depression. However, no difference was documented in feeding patterns of either treatment group. Hemoglobin count and liver weight of rats receiving the 2,000 mg/kg extract decreased.Husna 2013
There are no published reports of serious reactions in adults given the usual oral dose of 50 mL. Antifertility action (decreased spermatogenesis) has been observed in mice, rats, and dogs fed bitter melon fruit extract.Basch 2003, Chang 1995
In individuals with glucose-6-phosphate dehydrogenase deficiency, the seed constituent vicine may induce favism , an acute condition characterized by onset of hemolytic anemia and symptoms such as headache, fever, abdominal pain, and coma.Basch 2003, Raman 1996 Those deficient in glucose-6-phosphate dehydrogenase should avoid consumption of bitter melon preparations due to the presence of vicine in the seeds.
In a case report, atrial fibrillation occurred a 22-year-old man following consumption of juice from crushed M. charantia fruit.Erden 2010
Two case reports exist of hypoglycemic coma and convulsions in children following administration of a bitter melon tea.Basch 2003, Chevallier 1996
The red arils around bitter melon seeds may be toxic to children. In one report of a child given the juice, vomiting, diarrhea, and eventual death occurred.Duke 1989
References
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