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Start date: 2011
End date: 2014

This multidisciplinary and multinational collaborative project is led by AVRDC – The World Vegetable Center and funded by the Federal Ministry for Economic Cooperation and Development (BMZ), Germany. The project aims to improve the incomes and health of the poor in developing countries, particularly the quality of life of diabetics, through scientific research on bitter gourd (Momordica charantia L.).

Today, 285 million people in the world live with diabetes (Editorial comment, Lancet 2009) and 80% of those are in low-income and middle-income countries (WHO 2010). By 2030, about 4.5% (more than 370 million) of the world’s population will suffer from Type 2 diabetes (Wild et al. 2004). India has the highest number of diabetics, with 31.7 million in 2000 and a projected 79.4 million by 2030. The diabetes epidemic in sub-Saharan Africa is one of the fastest growing in the world, increasing 2.6 fold in 30 years (Wild et al. 2004).

Bitter gourd is eaten as a vegetable and used as a folk medicine for managing Type 2 diabetes in Asia and some African countries. There is no cure for diabetes, but the quality of life of people with diabetes depends on effective blood glucose control. Effective treatment includes proper diet, weight control, exercise, and medicine (DPPRG 2009).

Studies with animals and humans suggest bitter gourd (whole fruit, juice, or extract) has a role in diets for glycemic control of diabetes. The antidiabetic effect of bitter gourd results from the complex action of multiple compounds in the fruit. Studies are required to provide sufficient evidence to be able to recommend bitter gourd in managing Type 2 diabetes (Krawinkel and Keding 2006; Dans et al. 2007; Leung et al. 2009; Ooi et al. 2010). The project conducts multidisciplinary research on the antidiabetic effects of bitter gourd to provide the public with scientifically sound and accurate information.

  • Tanzania (Moshi, Arusha)
  • India (Coimbatore, Ludhiana, Hyderabad)
  • Taiwan (Taipei)
  • Germany (Giessen)
Project Manager
Dr. Ray-yu Yang, Food and Nutrition

AVRDC – The World Vegetable Center
Dr. Sandra Habicht, Biochemical Nutrition
Ms. Jen Wen Luoh, Community Nutrition
Dr. Peter Hanson, Plant Breeding
Mr. Chung-cheng Lin, Cucurbit Breeding
Dr. Madhusudan Bhattarai, Agricultural Economics
Dr. Andreas Ebert, Genebank
Ms. Dolores Ledesma, Biometrics
Ms. Maureen Mecozzi, Communications

AVRDC East and Southeast Asia
Dr. Narinder Dhillon, Cucurbit Breeding

AVRDC Africa
Dr. Chris Ojiewo, Horticulture
Dr. Victor Afari-Sefa, Agricultural Economics

AVRDC South Asia
Dr. Warwick Easdown, Horticulture

Avinashilingam Deemed University for Women
Dr. S. Premakumari, Socioeconomics
Dr. M. Amirthaveni Subramanian, Food and Nutrition

Justus-Liebig University Giessen
Dr. Michael Krawinkel, Medicine and International Nutrition
Dr. Sandra Habicht, Biochemical Nutrition
Ms. Christine Ludwig, Public Health Nutrition

Kilimanjaro Christian Medical Centre
Dr. Mark Swai, Paedatric Medicine

National Taiwan University
Dr. Ching-jang Huang, Biochemical Nutrition

Punjab Agricultural University
Dr. Mamta Pathak, Horticulture

Health Benefits of Bitter Gourd

by Dr. Sandra Habicht

Bitter gourd is a functional vegetable with beneficial effects on health
Bitter gourd is a popular vegetable in some Asian countries, where the health benefits of the plant are well-known—particularly, its ability to lower blood glucose in diabetics. Bitter gourd has been used to treat diabetes in traditional medicine and is now commercially available as tea (from fruits or leaves), juice, extracts, and pills. Although these products promise health benefits, most of the manufacturers do not offer scientifically proven data on the effectiveness of bitter gourd or their products. However, in recent years researchers worldwide have started to focus on the antidiabetic effects of bitter gourd. The goal is to provide safe and clear preparation and dosage recommendations so that consumers will realize the greatest benefit from consuming fresh bitter gourd or bitter gourd products.

It is scientifically proven: bitter gourd lowers blood glucose levels!
Bitter gourd treatments of cell cultures or feeding trials with laboratory animals such as mice or rats show bitter gourd does have blood glucose lowering properties. Bitter gourd is not like most medicinal drugs, which are effective only in one target organ or tissue; rather, it influences glucose metabolism all over the body.

Bitter gourd lowers dietary carbohydrate digestion
The glucose metabolism starts in the gut. Carbohydrates and sugars are metabolized to glucose (one type of sugar) before glucose is transported from the gut to the blood. Bitter gourd reduces the amount of glucose that is released into the blood by inhibiting the enzymes that break down disaccharides to two monosaccharides (e.g. glucose) (Oishi et al. 2007, Kumar Shetty et al. 2005). Bitter gourd can influence the transport channels for glucose, which also reduces glucose transport into the blood (Singh et al. 2004). This effect is important for the treatment of both Type I and Type II diabetic patients and helps to prevent high blood sugar levels after meals.

Bitter gourd plant insulin discovered
The pancreas reacts to increasing blood sugar levels by secreting insulin into the blood. Insulin helps to transport the sugar from the blood to the skeletal muscle and the fat tissue where it is used to produce energy. Insulin will also stop the liver to produce sugar from glycogen storages and to release the sugar into the blood. Thus, insulin is necessary to lower high blood sugar levels. In Type I diabetes, also called insulin-dependent diabetes, the pancreas does not produce or secrete enough insulin to keep blood sugar levels low. Bitter gourd has been shown to be effective in treating Type I diabetes in rats or mice by increasing pancreatic insulin secretion Yibchok-Anun et al. 2006, Fernandes et al. 2007). Additionally, scientists found an insulin-like molecule in bitter gourd (Khanna et al. 1981). Although bitter gourd may reduce the number of insulin injections required to manage Type 1 diabetes, it cannot replace insulin treatment completely or heal this form of the disease.

Bitter gourd reverses insulin resistance
Bitter gourd can play a role in the prevention and treatment of Type II diabetes, which is also called insulin-independent diabetes or adult onset diabetes. This form of the disease usually occurs in people who are overweight and inactive. In Type II diabetes, the liver, skeletal muscle, and fat tissues do not respond adequately to insulin—they are “insulin resistant.” Feeding trials with insulin resistant or Type II diabetic rats and mice have shown that bitter gourd helps to prevent or reverse insulin resistance (Nerurkar et al. 2008, Klomann et al. 2010). People with insulin resistance or those with a high risk of developing Type II diabetes have a good chance to prevent and treat the disease without drugs by increasing their physical activity and changing their diet.

Bitter gourd prevents diabetic complications
Chronically high sugar concentrations from Type I and Type II diabetes increase the risk of inflammation and oxidation in the whole body, leading to blindness, diabetic feet, kidney disease, stroke, or heart attack. Consuming bitter gourd can help prevent these complications, as it not only decreases blood sugar levels, but also has some antioxidative properties (Sathishsekar und Subramanian 2005, Klomann et al. 2010).

Bitter gourd can protect the body from other non-communicable diseases
Being overweight is one of the most important risk factors for diabetes and other diseases, and Type II diabetes is often accompanied by hypertension, high plasma cholesterol, or high plasma lipids. Together, these conditions increase the risk of stroke or heart attack. For overweight Type II diabetic patients, bitter gourd can help to improve health. In mice and rats, bitter gourd has been shown to reduce hypertension (Singh et al. 2004), plasma cholesterol (Nerurkar et al. 2008), and plasma lipids (Nerurkar et al. 2008). Apart from this, bitter gourd helps weight loss. There is also evidence that bitter gourd might be effective in cancer treatment.

More bitter gourd does not help more. Please be careful!
Exclusive consumption of bitter gourd, bitter gourd juice, or other bitter gourd products can lead to dangerous hypoglycemia when consumed by diabetic patients under oral drug treatment, in too high dosages, by children, or on a hungry stomach. Pregnant or breastfeeding woman should not consume bitter gourd or bitter gourd products. Although bitter gourd can help prevent insulin resistance or severe diabetic complications, it is important to consider situations in which bitter gourd may be harmful to your health.

References

Fernandes, NP., Lagishetty, CV., Panda, VS., Naik, SR.: An experimental evaluation of the antidiabetic and antlipidemic properties of a standardized Momordica charantia fruit extract. BMC Complement Altern Med 7(29). doi: 10.1186/1472-6882-7-29. 2007
Khanna, P., Jain, SC., Panagariya, A., Dixit, VP.: Hypoglycemic activity of polypeptide-p from a plant source. J Nat Prod 44(6). 648-655. 1981
Klomann, SD., Mueller, AS., Pallauf, J., Krawinkel, MB.: Antidiabetic effects of bitter gourd extracts in insulin resistant db/db mice. Br J Nutr, doi: 10.1017/S0007114510002680. 2010
Kumar Shetty, A., Suresh Kumar, G., Veerayya Salimath, P.: Bitter gourd (Momordica charantia) modulates activities of intestinal and renal disaccharidases in streptozotocin-induced diabetic rats. Mol Nutr Food Res 49(8). 791–796. 2005
Nerurkar, PV., Lee, YK., Motosue, M., Adeli, K., Nerurkar, VR.: Momordica charantia (bitter melon) reduces plasma apolipoprotein B-100 and inrcreases hepatic insulin receptor substrate and phosphoinositide-3 kinase interactions. Br J Nutr 100(4). 751-759. 2008
Oishi, Y., Sakamoto, T., Udagawa, H., Taniguchi, H., Kobayashi-Hattori, K., Ozawa, Y., Takita, T.: Inhibition of increases in blood glucose and serum neutral fat by Momordica charantia saponin fraction. Biosci Biotechnol Biochem 71(3). 735-740. 2007
Sathishsekar, D., Subramanian, S.: Beneficial effects of Momordica charantia seeds in the treatment of STZ-induced diabetes in experimental rats. Biol Pharm Bull 28(6). 978-983. 2005
Singh, J., Adeghate, E., Cummings, E., Giannikipolous, C., Sharma, AK., Ahmed, I.: Beneficial effects and mechanism of action of Momordica charantia juice in the treatment of streptozotocin-induced diabetes mellitus in rat. Mol Cell Biochem 261(1-2). 63-70. 2004
Yibchok-Anun, S., Adisakwattana, S., Yao, CY., Sangvanich, P., Roengsumran, S., Hsu, WH.: Slow acting protein extract from fruit pulp of Momordica charantia with insulin secretagogue and insulinomimetic activities. Biol Pharm Bull 29(6). 1126—1131. 2006.

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