What on Earth is bitter melon?
Good question. I certainly didn’t know before researching this article. Let’s start with some basics.
Momordica charantia is a fruit-bearing plant found in Asia, Africa and the Caribbean. It’s also known as bitter melon, bitter gourd, bitter squash, balsam-pear, karela, kugua or yeoju. It looks and tastes somewhat like a cucumber, and is used for cooking, beer brewing and as a medicinal ingredient for treating everything from diabetes to constipation to respiratory conditions.
Considering that, as of 2015, 3.4 million Canadians lived with diabetes, effective treatments for type 1 or 2 diabetes are highly sought after. Type 1 diabetes is treated with a variety of fast- and slow-acting insulin injections, and with the exception of injection-site reactions and allergic reactions, these are quite effective and safe, if very expensive. But treating type 2 diabetes is much more complex.
Where type 1 diabetes arises from a body’s inability to produce insulin, type 2 arises from a body developing insulin resistance, combined with an insufficient amount of insulin production from the pancreas. So, it’s not as simple as giving somebody the insulin they lack.
Instead, treatment for type 2 diabetes usually focuses heavily on proper nutrition and exercise, with some medications used as well. Metformin is commonly used to decrease liver glucose production and increase the cell’s sensitivity to insulin. Other medications can be used to increase insulin release or to decrease insulin resistance, but not all patients respond to these therapies (about 28% of those with type 2 diabetes end up requiring insulin therapy), and many have severe side effects like liver damage and heart failure.
In light of this situation, it’s easy to see why alternative treatments for type 2 diabetes are attractive to those suffering. But can bitter melon actually help, or is it just lowering your bank balance and not your blood sugar?
As with most (all) things, there isn’t an easy answer. Several studies (1,2,3) have found positive effects on some or many of the markers of type 2 diabetes, which include blood glucose levels, insulin levels, and glucose uptake rates. The first study referenced above is a review of 42 randomized controlled trials (RCTs) and 16 non-randomized controlled trials (NRCTs) on natural supplements for diabetes, but not all of those dealt with bitter melon, and the authors don’t specify how many did. The other two studies were performed on rats which, as we know, are not a perfect model for humans.
But for every study finding a positive result, there seems to be two with negative findings. This 2014 review of four RCTs looked at a total of 208 patients and found that bitter melon had no effect on A1C (amount of hemoglobin with attached glucose) or blood glucose levels. This 2015 study with 95 participants confirmed the hypoglycemic effects of bitter melon, but found it offered poor glycemic control compared to glibenclamide (a commonly prescribed medication for type 2 diabetes).
The most comprehensive review of the lot, done in 2012, examined four RCTs, a total of 479 patients, and found that bitter melon offer no difference in glycemic control compared to a placebo or to the medications metformin or glibenclamide.
There is some debate over the effects of the preparation and administration of the bitter melon on the results. In general, it seems that the fresher the better, with fruit smoothies and juices showing the best results, and capsules the worst. But even those best results are no better than a placebo.
There is some good news though. While its use as a diabetic treatment might be a bust, bitter melon shows some potential as an anti-HIV and AIDS drug. While preliminary studies have seemed positive, we’ll need to wait for the human trials to really evaluate these claims. The situation is much the same for bitter melon’s fate as an anti-cancer drug. Only time (and more research) will tell.
As well, throughout these studies no serious adverse effects were reported. If any side effects were experienced they were mild: fever, diarrhea, stomach aches, etc.
So bitter melon is a supplement of questionable use. Perhaps best kept in a kitchen cabinet for cooking, rather than a medicine cabinet for treatment.