Bitter melon (Momordica charantia) is also known as bitter gourd, bitter cucumber, bitter apple, karolla and karela.

Bitter melon is a member of the Cucurbitaceae family and is related to honeydew and Persian melon, cantaloupe, muskmelon and casaba. Bitter melon is a vegetable cultivated and eaten in many parts of the world, including India, Asia, Africa and South America.

Bitter melon grows on a vine with green leaves and yellow flowers. The fruit has a bumpy exterior, resembling a cucumber, and the interior is yellow-orange. There are many varieties of bitter melon, ranging in color from creamy white, golden, pale green to very dark green. Green melons are the ones most often seen in the United States. Some varieties are only a few inches long with very pronounced bumps; others are much larger with smoother, less-defined bumps.

The fruit and seeds of bitter melon are thought to be useful for diabetes.

Some Ingredients May Lower Blood Glucose

Bitter melon contains several chemical ingredients, including the glycosides momordin and charantin. Polypeptide P, charantin and vicine are the specific components thought to have blood glucose-lowering effects.

Other possible mechanisms in diabetes include increased tissue glucose uptake, liver and muscle glycogen synthesis, inhibition of enzymes involved in glucose production and enhanced glucose oxidation.

Cautions About Bitter Melon

Bitter melon should be used with caution by young women of childbearing age since it may induce menstruation and inadvertently cause abortion if the woman is pregnant.

There is no information about its use in lactating women, so it should be avoided.

Children should not use bitter melon because serious adverse effects have occurred, including hypoglycemic coma.

There is no traditional dose of bitter melon since different forms are in use, including juice, powder, vegetable pulp suspensions and injectable forms.

Few studies have evaluated using bitter melon in the treatment of diabetes.

The largest study, published in a 1999 issue of the Bangladesh Medical Research Council Bulletin, used an aqueous suspension of bitter melon vegetable pulp in 100 patients with type 2. The authors evaluated the effect at one hour after bitter melon was administered and then two hours after a 75-gram oral glucose tolerance test.

The average blood glucose was 222 mg/dl, which was lower than the previous day’s two-hour value of 257 mg/dl.

In another study, published in a 1981 issue of the Journal of Natural Products, bitter melon was prepared as an injectable “plant insulin” and injected into five patients with type 1 and six patients with type 2. There was a control group of six patients 6 with type 1 and two patients with type 2 who did not receive any bitter melon.

In type 1s, average glucose decreased from 304 to 169 mg/dl four hours after injection; this effect was maintained at six and eight hours after injection.

In the type 2 patients, there was no significant decline in blood glucose from baseline.

Side Effects of Bitter Melon

The major side effect of bitter melon is gastrointestinal discomfort.

A syndrome called favism, or hemolytic anemia, has occurred in people taking bitter melon. It is characterized by headache, fever, abdominal pain and coma. The red coating around the seeds have been reported to cause vomiting, diarrhea and death in one child.

When bitter melon is combined with sulfonylureas, hypoglycemia can occur.