Bitter melon is a cucurbitaceous plant that is commonly found in regions such as Asia, South America, and India, among others. It belongs to the gourd family and is known for its various physiological effects, including antioxidative, anti-tumor, anti-inflammatory, antimicrobial, digestive improvement, neuroprotection, and its positive impact on metabolic disorders like obesity, cholesterol reduction, and blood sugar regulation. Therefore, it is widely consumed by residents of tropical, subtropical, and temperate regions. Besides its use in cooking, bitter melon products such as bitter melon juice, related beverages, bitter melon powder, or bitter melon capsules are also available in the market.
Many ingredients that taste bitter or are used in traditional Chinese medicine have been found to have certain therapeutic effects. Today, we will introduce an ingredient that carries a bitter taste but is more commonly found in our daily meals: bitter melon. Bitter melon has been scientifically shown to have various physiological effects, and today, we will focus on discussing its most significant effect, which is its ability to reduce blood sugar levels.
Can Bitter Melon Peptides Lower Blood Sugar and Be a Savior for Diabetes?
Bitter melon is a cucurbitaceous plant commonly found in regions like Asia, South America, India, and more. It is known for its numerous physiological effects, including antioxidative, anti-tumor, anti-inflammatory, antimicrobial, digestive improvement, neuroprotection, and its positive impact on metabolic disorders like obesity, cholesterol reduction, and blood sugar regulation. As a result, it is widely consumed by residents of tropical, subtropical, and temperate regions. In addition to its culinary uses, bitter melon products such as soluble extracts, bitter melon powder, or bitter melon capsules are available in the market.
Numerous experiments have indicated that bitter melon and its extracts have excellent blood sugar-regulating capabilities. In a human trial, diabetes patients were given either bitter melon water-soluble extracts or bitter melon powder for three consecutive weeks. The study found that these treatments effectively reduced blood sugar levels and could help prevent diabetes-related complications [1]. Another study discovered that giving 100 type 2 diabetes patients bitter melon juice lowered fasting blood sugar levels and delayed the increase in blood sugar levels after meals [2].
In another clinical trial over seven days, type 2 diabetes patients were divided into two groups. One group received only oral blood sugar-lowering medication, while the other group received half the dose of the medication along with bitter melon extract. The results showed that the group combining bitter melon extract with the medication, even at half the dose, achieved better blood sugar reduction compared to the other group [3].
In another three-month randomized controlled trial, it was found that bitter melon extract (2.3 grams per day) had a positive effect on lowering blood sugar and improving insulin sensitivity in type 2 diabetes patients compared to a placebo group [4]. One crucial blood sugar-lowering component in bitter melon is ‘bitter melon peptide,’ which has been shown in early clinical trials to improve fasting blood sugar levels and long-term blood sugar monitoring markers like HbA1c [5].
What Are Bitter Melon Peptides?
In addition to its three major nutrients, bitter melon is rich in dietary fiber, vitamins, and trace minerals. Recent research has identified several highly beneficial compounds, such as phenols, saponins, alkaloids, polysaccharides, triterpenes, special proteins, flavonoids, steroids, and glycosides.
Insulin-like peptides have shown significant blood sugar-lowering effects among the various active ingredients in bitter melon. So, what exactly are bitter melon peptides? They are active proteins and their hydrolyzed products isolated from bitter melon extracts, collectively known as ‘bitter melon peptides.’ Some of these peptides have been successfully sequenced and named, and many companies have even applied for patents after sequencing these peptides.
What Are the Benefits of Bitter Melon Peptides?
Bitter melon peptides refer to a large group of proteins and their hydrolyzed products extracted from bitter melon. As a result, different bitter melon peptides have different effects. Here are some of their notable benefits:
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Blood Sugar Control
A study involving 64 diabetes patients who supplemented with bitter melon peptides for three months found that the group taking these peptides had fasting blood sugar levels lower than 126 mg/dL, and their HbA1c levels also significantly improved compared to the non-supplement group [9]. Bitter melon can achieve blood sugar reduction through various mechanisms, such as promoting insulin secretion, increasing skeletal muscle glucose utilization, reducing glucose absorption, or enhancing pancreatic β-cell function. There is also specific research on how bitter melon peptides achieve blood sugar-lowering effects.
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Insulin Mimicry
In a diabetes animal model, injections of polypeptide-p (2.5 mg per kilogram of body weight) showed similar blood sugar reduction effects at 1, 2, and 4 hours after intervention compared to insulin injections [6].
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Stimulation of Insulin Secretion
Feeding diabetes animals with 20 mg per kilogram of body weight of bitter melon peptide extract showed significant blood sugar reduction at 30, 60, and 120 minutes. After 28 days of feeding, both the bitter melon peptide group and the group using oral blood sugar-lowering medication, glibenclamide, exhibited the ability to stimulate pancreatic insulin secretion and reduce fasting blood sugar levels. Apart from blood sugar regulation, this intervention also helped reduce total cholesterol, low-density lipoprotein cholesterol (LDL-C) levels while increasing high-density lipoprotein cholesterol (HDL-C) levels [7].
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Delaying Carbohydrate Absorption
Bitter melon protein extract was found to inhibit the activity of α-amylase and α-glucosidase enzymes in an in vitro experiment. These two enzymes play a crucial role in carbohydrate food breakdown, and excessive activity can lead to a rapid rise in post-meal blood sugar levels. In a diabetes animal model, giving the animals bitter melon protein extract showed comparable abilities to Acarbose, an oral blood sugar-lowering drug, in delaying post-meal blood sugar levels [8].
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Anti-Tumor Effects
Bitter melon extract has the ability to inhibit the growth of breast cancer cells and improve the survival rate of breast cancer model animals [10]. Another study found that bitter melon peptides could induce apoptosis in colon cancer cells, which helps in preventing the progression of colon cancer [11].
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Blood Pressure Reduction
Two segments of peptides with blood pressure-lowering abilities were identified in bitter melon extracts. Through in vitro experiments, these peptides were found to inhibit the activity of angiotensin-I converting enzyme (ACE), which is positively correlated with blood pressure, as ACE enzyme activity is related to high blood pressure. One class of blood pressure-lowering drugs includes ACE inhibitors, and bitter melon peptides demonstrated effective blood pressure reduction in a high blood pressure animal model [12].
How to Consume Bitter Melon Peptides Effectively?
Since bitter melon peptides represent a large group of proteins and their hydrolyzed products, the effective dosage of different peptide segments can vary significantly. Therefore, it is recommended to follow the experimental data provided by the manufacturer or the dosage instructions on the packaging. Common recommended daily dosages typically range from 500 to 1000 milligrams.
Are There Side Effects and Contraindications for Consuming Bitter Melon Peptides?
Large direct consumption of bitter melon has been reported to lead to adverse effects, including gastrointestinal discomfort, diarrhea, headaches, or even coma due to low blood sugar. Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency may experience symptoms similar to favism after consuming bitter melon. Animal experiments have shown that excessive intake of bitter melon may affect fertility and even cause miscarriages [13].
Compared to bitter melon, bitter melon peptides are purified segments of bioactive peptides extracted from bitter melon. They have fewer side effects and are considered safe. It’s advisable to consult with a healthcare professional before supplementation, especially when combining them with medications to avoid potential interactions between drugs and nutrients.
Bitter melon has been widely used in many dietary therapies, and with the identification of its essential blood sugar-lowering component, bitter melon peptides, supported by numerous clinical trials, it has become a significant player in blood sugar management. Therefore, it is essential to choose products that are extracted using patented technology, have comprehensive international clinical research data, and are confirmed to contain effective dosages of bitter melon peptides to ensure the safe and effective use of bitter melon peptide supplements.
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