Studies: Effectiveness of bitter melon against diabetes

Studies: Effectiveness of bitter melon against diabetes

Momordica charantia or bitter melon is a tropical and subtropical vine that is widely cultivated in South and Southeast Asia, East Asia, South America, the tropical and subtropical regions in Africa, and the Caribbean. As a member of the Cucurbitaceae family, it is taxonomically related to the squash, pumpkin, watermelon, cucumber, and melons, among others.

It is important to highlight the fact that the bitter melon is the edible part or fruit of the Momordica charantia plant. Nonetheless, the fruit is consumed cooked or uncooked depending on regional and cultural culinary varieties. The young shoots and leaves of the plant may also be eaten as greens.

Moreover, aside from its culinary use, this plant has been used in a variety of traditional Asian and African herbal medicinal practices. Manufacturers of food supplements have processed different parts of this plant to capitalize on its supposed medicinal properties.

One of the notable traditional medicinal uses of bitter melon that has caught the interest of the scientific community centers on its purported effect against diabetes mellitus, primarily because of its supposed hypoglycemic effects or in its role in lower blood glucose or blood sugar level. Several studies have been conducted to examine its efficacy as a possible antidiabetic drug.

The Effectiveness of Bitter Melon Against Diabetes

What Are the Properties or Chemical Constituents of Bitter Melon that Make it a Candidate Antidiabetic Drug?

The fact remains that Momordica charantia or bitter melon has specific properties or chemical compositions that provide antidiabetic and hypoglycemic properties. The review study of B. Joseph and D. Jini identified and described three substances that have these properties. These are charantin, vicine, and polypeptide-p.

Charantin is a chemical substance naturally found in Momordica charantia. Several studies have reported the hypoglycemic effects of this substance. In fact, there have been studies showing that charantin is more effective than the orally administered hypoglycemic drug tolbutamide.

On the other hand, vicine is an alkaloid glycoside found in the seeds of bitter melon, as well as in fava beans. Studies exhibited that it can induce hypoglycemia in non-diabetic fasting rats through intraperitoneal administration. However, the review study of B. Joseph and D. Jini noted that vicine found in fava beans triggers a condition called favism characterized by acute hemolytic anemia in individuals with a hereditary predisposition.

Polypeptide-p is another substance found in bitter melon. It is an insulin-like compound or hypoglycemic protein, and as such, it is also called as p-insulin. Studies showed that it could lower blood glucose levels in animal models and humans when injected subcutaneously. Accordingly, polypeptide-p mimics the action of insulin in the human body. Nonetheless, other studies suggest that it might be a suitable plant-based insulin replacement for individuals with type 1 diabetes. 

What does the Literature Say About the Effectiveness of Momordica Charantia in Managing Diabetes Mellitus?

A 2013 review study by B. Joseph and D. Jini noted that there is an abundance of preclinical studies that have examined the effects of Momordica charantia in lowering blood glucose or blood sugar levels. However, the documented effects are still not absolute because of the absence of human clinical trials and the persistence of poor study design and unsatisfactory statistical authority.

R. V. Yin et al. also published the results of the systematic review and meta-analysis in 2014. Their study mentioned that data from previous studies offered mixed conclusions regarding the efficacy or benefits of bitter melon in individuals with type 1 and type 2 diabetes. Furthermore, their meta-analysis of these conclusions revealed no statistically significant effect for the use of bitter melon for controlling A1C or the three-month blood glucose levels and fasting plasma glucose or FPG.

Of course, researchers B Joseph and D. Jini, as well as Yin et al. explained that there is a need for a larger and more robust study involving a larger sample of patients assessed over a longer duration or better designed human clinical trials to unequivocally determine that Momordica charantia or bitter melon is genuinely ineffective in managing type 1 or type 2 diabetes.

What are the Benefits of Bitter Melon Supplementation in Lowering Blood Glucose Level and Preventing Cardiovascular Diseases?

Despite the lack of absolute evidence explaining and determining the effectiveness of bitter melon in treating or managing diabetes mellitus, studies about the effects of this plant in lower blood sugar level and decreasing the risk of cardiovascular diseases remain noteworthy.

Animal models such as the 2018 study by Ummi Rohajatien et al. showed that Momordica charantia effectively decreased the blood sugar level and improved the lipid profile of rats subjected under induced hyperglycemia. A 2003 study by Q. Chen, L. L. Y. Chan, and E. T. S. Li involving rats fed with a high-fat diet also showed that bitter melon reduced adiposity or susceptibility to overweightness and obesity, lowered serum insulin, and normalized glucose tolerance.

There have been studies conducted on human patients as well. The 2018 study of Michael B. Krawinkel et al. involved a randomized placebo-controlled single-blinded clinical trial with 52 prediabetic individuals. Results revealed that the group provided with bitter melon supplementation demonstrated lowered elevated fasting plasma glucose.

However, another 2015 study by Inayat U. Rahman et al. involving type 2 diabetic patients showed that Momordica charantia or bitter melon had a weaker hypoglycemic effect or lower efficacy in bringing down blood sugar levels than glibenclamide—an antidiabetic drug belonging to the class of medications called sulfonylureas. Still, the same study showed that bitter melon had better antiatherogenic effects or in other words, it manages cardiovascular risk factors associated with type 2 diabetes more effectively than glibenclamide.

Conclusion: Is Bitter Melon Effective in Managing Diabetes?

The discussion above showed that there are a considerable number of studies demonstrating and explaining the hypoglycemic effects of Momordica charantia or bitter melon. This role in lowering blood glucose or blood sugar levels, as well as other beneficial effects to include decreasing risk from glucose-related cardiovascular diseases, stems from the properties or chemical substances naturally found in the plant.

However, the entire literature remains stern with its conclusion about bitter melon. There is not absolute evidence indicating that bitter melon can be an effective and efficient supplement for treating or managing type 1 and type 2 diabetes. It is still not a viable alternative antidiabetic drug unlike metformin and glibenclamide or other sulfonylureas. Of course, the researchers noted that concluding the ineffectiveness of bitter melon also requires the same clinical trials conduced over a long duration.

FURTHER READINGS AND REFERENCES

  • Chen, Q., Chan, L. L. Y., and Li, E. T. S. 2003. “Bitter Melon (Momordica Charantia) Reduces Adiposity, Lowers Serum Insulin, and Normalizes Glucose Tolerance in Rats Fed a High Fat Diet.” The Journal of Nutrition. 133(4): 1088-1093. DOI: 10.1093/jn/133.4.1088
  • Joseph, B. and Jini, D. 2013. “Antidiabetic Effects of Momordica Charantia (Bitter Melon) and its Medicinal Potency.” Asian Pacific Journal of Tropical Disease. 3(2): 93-102. DOI: 10.1016/S2222-1808(13)60052-3
  • Krawinkel, M. B., Ludwig, C., Swai, M. E., Yang, R., Chun, K. P., and Habicht, S. D. 2018. “Bitter Gourd Reduces Elevated Fasting Plasma Glucose Levels in an Intervention Study Among Prediabetics in Tanzania.” Journal of Ethnopharmacology. 216: 107. DOI: 10.1016/j.jep.2018.01.016
  • Rahman, I. U., Khan, R. U., Rahman, K. U., and Bashir, M. 2015. “Lower Hypoglycemic But Higher Antiatherogenic Effects of Bitter Melon than Glibenclamide in Type 2 Diabetic Patients.” Nutrition Journal. 14(3). DOI: 10.1186/1475-2891-14-13
  • Rohajatien, U., Harijono, Estiasih, T., and Sriwahyuni, E. 2018. “Bitter Melon Fruit Decreased Blood Glucose Level and Improved Lipid Profile of Streptozotocin Induced Hyperglycemia Rats.” Current Research in Nutrition and Food Science. 6(2). DOI: 10.12944/CRNFSJ.6.2.11
  • Yin, R. V., Lee, N. C., Hirpara, H., and Phung, O. J. 2014. “The Effects of Bitter Melon (Momordica Charantia) in Patients with Diabetes Mellitus: A Systematic Review and Meta-Analysis.” Nutrition and Diabetes. 4(12): e145. DOI: 10.1038/nutd.2014.42