Bitter melon, also known as bitter gourd, bitter cucumber or karela, is a gourd-like plant widely cultivated in Asia, India, Africa and South America. It has long been used in traditional remedies, including some for diabetes, according to Kaiser Permanente.
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While bitter melon's blood sugar-lowering properties have been demonstrated in the laboratory and in animal studies, research focusing on the use of bitter melon in people with diabetes is limited and results have been inconclusive. More research is needed to establish bitter melon's efficacy, safety, appropriate dosage and potential interactions — including interactions with diabetes medications.
Bitter Melon Research
A study on rats, published in the March 2015 Journal of Nutritional Biochemistry, found that bitter melon helped prevent insulin resistance, a major cause of prediabetes and type 2 diabetes, according to the Mayo Clinic. Bitter melon also helped increase levels of insulin, one of the major hormones responsible for lowering blood sugar, according to a meta-analysis published in Current Diabetes Reviews in 2014.
The analysis also found that bitter melon improved glucose (blood sugar) uptake and utilization in people with type 2 diabetes. Bitter melon studies on people with type 2 diabetes have been poorly designed, but the plant also seems to be safe for humans and may improve blood sugar control, according to the review. However, much more high-quality research is needed.
Although bitter melon has a long history in folk medicine as a diabetes treatment, there is no modern scientific consensus on its efficacy, Heidi Karner, a registered dietitian nutritionist at Harvard's Joslin Diabetes Center, tells LIVESTRONG.com. "I've seen studies that show [bitter melon] lowers blood sugar, and studies that say it does nothing at all," she says. "There's currently no [conclusive] evidence either way. We may have answers in a few years. We'll just have to wait and see."
Bitter Melon Dosages
Bitter melon fruit is often sold in specialty Asian markets. The fruit can be eaten as is, or it can also be consumed as juice or tea. Alternatively, bitter melon extracts and powders can be purchased online or in many health food stores.
Kaiser Permanente lists the daily bitter melon diabetes dosage as 50 to 100 milliliters of juice or 5 grams of powdered fruit, taken three times per day, but the website warns that more research is needed to support these doses.
A small study of 24 people published in July 2018 in the Journal of Medicinal Food found that a bitter melon dosage of 2,000 milligrams per day improved insulin secretion and was also effective in lowering average blood sugar levels (hemoglobin A1C).
Overall, research on using bitter melon to treat diabetes is still new and conflicting; to date, there's no agreement on the appropriate dosage or even on what form of bitter melon is most effective. If you are interested in trying a bitter melon supplement, speak with your diabetes care team first.
Bitter Melon Side Effects
According to Memorial Sloan Kettering Cancer Center (MSKCC), pregnant women should not consume bitter melon because there have been reports of serious adverse reactions, including vaginal bleeding and induced miscarriage. People who take insulin should not use bitter melon either, since the additive effect could result in too-low blood sugar, according to MSKCC.
Though bitter melon is usually well-tolerated by the general population, excessive ingestion of bitter melon seeds can lead to headaches, fever, stomach pain or even coma, according to MSKCC. Studies on rodents have also found that high doses of bitter melon can cause liver damage, however this effect has not yet been observed in humans.
Always check with your doctor about any complementary or alternative health approaches you are considering, and do not discontinue or change the dose of any medications you are currently taking without your doctor's approval. Larger clinical trials on humans are needed to better understand the effect of bitter melon on blood sugar. Therefore, this supplement should not be used as a substitute for any diabetes medication prescribed by a doctor.
- Journal of Nutritional Biochemistry: "Preventive Effects of Bitter Melon (Momordica Charantia) Against Insulin Resistance and Diabetes Are Associated With the Inhibition of NF-κB and JNK Pathways in High-Fat-Fed OLETF Rats"
- Kaiser Permanente: "Bitter Melon"
- Mayo Clinic: "Type 2 Diabetes"
- Current Diabetes Reviews: "Momordica Charantia and Type 2 Diabetes: From In Vitro to Human Studies"
- Journal of Medicinal Food: "Momordica Charantia Administration Improves Insulin Secretion in Type 2 Diabetes Mellitus"
- Memorial Sloan Kettering Cancer Center: "Bitter Melon for Adult Patients"
- Drugs.com: Bitter Melon