Don’t let the name deceive you. Bitter melon, also known as bitter gourd or by its scientific name Mormordica charantia, may be just what the doctor ordered, especially for those at risk for diabetes. Widely consumed in Asia, this tropical vegetable has been shown by a number of biomedical studies to have anti-diabetic properties.
To discover the next trend in functional foods, it is sometimes useful to take a look at what is going on around the world. Several new health-promoting food products in the Philippines, for example, are based on ampalaya – otherwise known as charantia, bitter melon or bitter gourd. While the latter names might not seem appealing in terms of taste, there are extraction and processing methods to get around the bitterness. More importantly, this intriguing vegetable (which is widely consumed in Southeast Asia, China, and India as a component of traditional dishes) is certainly very attractive in terms of its potential benefits to human health, particularly in terms of its apparent ability to regulate insulin sensitivity and blood glucose levels – both of significant interest for the prevention and treatment of type 2 diabetes.
Once an isolated medical phenomenon, diabetes is increasingly a topic of discussion for consumers and food manufacturers alike. The recent and alarming rise in incidence of type 2 diabetes can only be described as an epidemic (and is actually classified as such by the US Centers for Disease Control and Prevention). Also known as adult-onset diabetes or non-insulin-dependent
diabetes, this disorder involves the gradual development of insulin resistance and hyperglycaemia, as well as relative insulin deficiency. While genetic and other environmental influences are clearly also risk factors, the primary cause of type 2 diabetes is preventable – namely, sustained excess food intake, particularly of foods high in sugar. In any case, it is unlikely that consumer education campaigns – by governmental and health organisations on the one hand, and food manufacturers on the other – will be sufficient on their own to thwart this growing epidemic, which is now also increasingly taking hold in Europe and Asia. For this reason, the development and promotion of healthier foods low in carbohydrates, as well as functional foods with anti-diabetic properties, will play a growing role for food manufacturers around the world.
Towards this end, bitter melon appears to be an attractive ingredient for the formulation of new functional foods designed to help control blood glucose levels and boost insulin sensitivity. Known as “ampalaya” in the Philippines and as “pare” in Indonesia, bitter melon is native to the tropics (its exact origin is a matter of debate), and is widely cultivated in Southeast Asia, China, South Asia, Africa and the Caribbean. Also known as balsam pear or balsam apple, it is a member of the gourd family (Cucurbitaceae), which also includes squash, watermelon, muskmelon, and cucumber. It is one of the most bitter vegetables eaten by humans; this bitterness can be reduced by blanching or salting. The nutritional value of bitter melon is impressive – on average, a 100-gram serving contains 44 kcal, 5.6 g protein, 290 mg calcium, 5 mg iron, 5.1 mg vitamin A and 170 mg vitamin C. It is also a good source of phosphorus, potassium, beta carotene, and dietary fibre. However, the key ingredients of bitter melon are those responsible for its anti-diabetic properties – compounds known as momordicosides.
In the March issue of Chemistry and Biology, a leading academic journal, reseachers at the Shanghai Institutes for Biological Sciences report their findings on the mechanism of action of momordicosides isolated from bitter melon. Focusing on four compounds (momordicosides Q, R, S and T, all of which are classified as cucurbitane glycosides), the Chinese team saw a number of effects clearly beneficial for the prevention and treatment of both diabetes and obesity. For example, in both muscle cells and fat cells, the compounds stimulated mechanisms essential for glucose uptake and fatty acid oxidation. In glucose tolerance tests in both insulin-sensitive and insulin-resistant mice, momordicosides boosted fatty acid oxidation and glucose disposal, indicating the potential of these triterpenoids as possible drug candidates for diabetes and obesity.
Numerous other studies have been carried out over the years, most of which show bioactivities in animal models or in cell culture that can clearly be considered beneficial for type 2 diabetes. Data from clinical trials are also available, and indicate a moderate hypoglycaemic effect of bitter melon, as evidenced through the regular intake of juice, fruit and dried powder. Nevertheless, these studies were small, not randomised, nor double-blinded, necessitating the performance of larger, adequately controlled trials to properly assess safety and efficacy. In addition, as is the case for any plant derivative, it will be very important to carefully control the phytochemical composition of these natural materials, which are subject to sometimes considerable variation based on multiple parameters (plant variety, growth conditions, time of harvest, environmental conditions). To minimise confounding effects caused by these variables, future trials should focus on the analysis of standardised extracts. In the meantime, however, the sum of all evidence in animals and humans strongly suggests that bitter melon may be a useful component of a diet designed to prevent the onset of, or manage the effects of, type 2 diabetes.
As with any functional food or nutraceutical, manufacturers need to be careful not to overstate the potential health benefits associated with their active ingredients. In October 2007, the US Food and Drug Administration (FDA) seized over $70,000 worth of bitter melon-based products from Fullife Natural Options, a marketer and distributor of dietary supplements located in Boca Ration, Florida. The reason for this enforcement action? According to the FDA, the company sold its Charantea Ampalaya capsules and Charantea Ampalaya tea with claims that these were suitable for treatment of serious medical conditions – not only diabetes, but also anaemia and hypertension. Such claims, relating either to the prevention or to the treatment of diseases, define a product as a drug, which therefore cannot be legally marketed without first being shown to safe and effective.
In the case of Fullife, these claims were made on the products’ labelling, as well as on promotional literature and the company’s web site – in violation of the drug and misbranding provisions of the Federal Food, Drug and Cosmetic Act (FFCDA). The health benefits claimed for its Charantea products included testimonials from its customers, such as “Charantea helps me lower my blood sugar level naturally,” and “with Charantea fortifying my diet, my doctor is able to reduce my medication.” It is worth noting that Fullife had been warned one year earlier by the FDA that its marketing practices were not in compliance with the FFCDA, but had not changed these offending claims in the intervening period. As a result, US Marshals seized the Charantea products at the request of the FDA. To avoid a similar fate, manufacturers considering the use of bitter melon as an ingredient in functional food or nutraceutical products should be keenly aware of these restrictions, and should not make overt health claims as to the anti-diabetic properties of these products.
A number of issues exist which will need to be addressed prior to the appearance on supermarket shelves of large numbers of products containing bitter melon as a functional ingredient. First, the name. Very few consumers not already familiar with the health benefits of this plant will be encouraged to taste a new food product that has on its label an ingredient termed “bitter melon”. It would be advisable to use an alternative such as “charantia”, and to coordinate marketing efforts and information campaigns accordingly, so that consumers become aware of the health benefits of “charantia”, and not just of “bitter melon”. Second, the taste. There is still some debate as to whether compounds responsible for the bitter taste of charantia are the same ones responsible for its anti-diabetic properties. There are bound to be multiple compounds responsible for each property. Is there an overlap between the two groups? If there is no overlap or only a partial one, is it possible to develop extracts which include the beneficial compounds and avoid the bitter ones? Alternatively, is it possible, over time at least, to breed varieties of charantia that are not bitter but which retain their health-promoting properties? Several possibilties exist here for ingredient suppliers to develop unique and possibly patentable products. Third, consumer awareness. As alluded to above, very few consumers in Europe and the United States are currently aware of charantia and its potential benefits for diabetes. Manufacturers would need to do their part to help promote awareness of of this remarkable plant.
Finally, it is worth remembering that the use of charantia as an ingredient in functional foods would not require regulatory approval (provided, of course, that no excessive health claims are made), as charantia is already sold and consumed as a food in most major markets around the world. Asia has already taken the lead with regard to charantia-containing health foods and dietary supplements. It should therefore only be a matter of time before the first functional foods containing charantia become available in the US and Europe as well.
The author
Camilla Alexander
Nutraventures, a Belgium-based consulting group focusing on functional foods and nutraceuticals
