I have type 2 diabetes and am taking the drug metformin, but I've heard that bitter melon is a natural treatment that can reduce blood sugar. Is that true? And is it safe?
Bitter melon (Momordica charantia), also called balsam-pear, is a relative of the cantaloupe and watermelon—it looks like a lime-green cucumber with lots of warts. It has been used for centuries in traditional Chinese and Ayurvedic medicine to treat diabetes. Surprisingly, there are no well-done empiric studies on whether regularly eating bitter melon can reduce blood sugar. However, based on a few animal and small human trials using extracted components of the fruit, it's likely that there's something to that traditional use. Exactly how much one would eat and how it would be prepared to maximize the blood sugar benefit is unknown. When you're planning diabetes-friendly meals, though, it's always good to have nonstarchy vegetables—such as bitter melon—to round out your plate and help fill you up. A cooked cup of bitter melon has only 24 calories, five grams of carbohydrate and two grams of sugar. Yet it's a great source of vitamin C and supplies good amounts of fiber, potassium and B vitamins, especially folate. If bitter melon helps reduce your blood sugar response to a meal, so much the better. Many people like the bitter taste, but if you don't, it might occur to you that a bitter melon supplement might help instead. Researchers have isolated 228 compounds from bitter melon fruit that may have medicinal properties alone or in combination. Unfortunately, clinical studies of supplements containing extracts of these active ingredients have not shown conclusively or consistently that they reduce blood sugar. Further research might yield such a supplement, but I am not aware of any that has strong scientific evidence behind it. So I'd encourage you to experiment with bitter melon as a food, but be very cautious about it as a supplement. That's especially true for you since you are already taking a blood-sugar–lowering medication, metformin. If some sort of bitter melon supplement does turn out to substantially reduce blood sugar—which is certainly possible—just adding it to your regimen by yourself might make your blood sugar drop too low (hypoglycemia), which can be dangerous. If you want to try a bitter melon supplement, make sure that you discuss it—and all supplements you take, for that matter—with your doctor. You can find bitter melon in Asian and Indian grocery stores and at some farmers’ markets. Like cucumbers, it can be eaten raw (in salads, thinly sliced, or in smoothies paired with a fruit juice such as apple) or cooked (sautéed or stir-fried). The skin of bitter melon is edible, although some people prefer to peel it, but the seeds and inner pith should be scraped out before eating. To Western palates, the flavor of bitter melon is an acquired one...it is indeed quite bitter...but salty foods cut the bitterness, so try adding Chinese fermented black beans or some miso to a prepared dish. Here’s a well-reviewed classic Indian bitter melon recipe that you could turn into a main dish with the addition of chicken or tofu. For more tips on bitter melon, see the Bottom Line articles "Beyond Broccoli: The Healthiest Foods on the Planet That You Haven’t Tried" and "How America’s Top Diabetes Doctor Avoids Diabetes."