Researchers gave extracts of the herb Salacia oblonga to 39 healthy adults, and the results were promising. The largest dose of the herb extract – 1,000 milligrams – decreased insulin and blood glucose levels by 29 and 23 percent, respectively.
“These kinds of reductions are similar to what we might see with prescription oral medications for people with diabetes,” said Steve Hertzler, a study co-author and an assistant professor of nutrition at Ohio State University.
Salacia oblonga, which is native to regions of India and Sri Lanka, binds to intestinal enzymes that break down carbohydrates in the body. These enzymes, called alpha-glucosidases, turn carbohydrates into glucose, the sugar that circulates throughout the body. If the enzyme binds to the herbal extract rather than to a carbohydrate, then less glucose gets into the blood stream, resulting in lowered blood glucose and insulin levels.
“Lowering blood glucose levels lowers the risk of disease-related complications in people with diabetes,” Hertzler said. “Also, poor compliance with diabetes medications often hinders the effectiveness of these drugs. It may be easier to get someone to take an herb with food or in a beverage, as opposed to a pill.”
The study appears in a recent issue of the Journal of the American Dietetic Association.
Thirty-nine healthy adults participated in four separate meal tolerance tests. These meals, which were given in beverage form, were spaced three to 14 days apart. Each participant fasted for at least 10 hours before consuming the test beverage.
Participants were asked to drink about two cups’ worth of the chilled beverage, which contained zero, 500, 700 or 1,000 milligrams of Salacia oblonga extract. Afterward, the researchers used the finger-prick method to draw blood samples from each person every 15 to 30 minutes for three hours. These blood samples were used to determine insulin and blood glucose concentrations. The biggest changes in blood glucose and insulin levels usually happen within the first two hours after eating.
The beverage that contained the highest concentration of the herbal extract – 1,000 milligrams – provided the most dramatic reduction in insulin and blood glucose levels. Insulin levels were 29 percent lower, while blood glucose levels were 23 percent lower as compared to the control drink, which contained no herbal extract.
As Salacia oblonga can cause intestinal gas, the researchers had the study participants collect breath hydrogen samples hourly for eight hours after drinking the test beverage. The participants collected their breath in small plastic tubes. The researchers then analyzed these breath samples for hydrogen and methane content – the level of either substance in the breath corresponds to the level contained in the colon.
The subjects also rated the frequency and intensity of nausea, abdominal cramping and distention and gas for two days after consuming each test meal.
While the test beverages containing Salacia oblonga caused an increase in breath hydrogen excretion, reports of gastrointestinal discomfort were minimal, Hertzler said.
Right now he and his colleagues are trying to figure out what dose of the herb is most effective, and when it should be taken relative to a meal.
“We want to know how long it takes for the herb to bind to the enzymes that break down carbohydrates,” Hertzler said. “The participants in this study took the herb with their meal, but maybe taking it before eating would be even more effective.”
The researchers also want to study the effects of Salacia oblonga in people with diabetes.
“A lot of studies show that lowering blood sugar levels reduces the risk for all kinds of diabetes-related complications, such as kidney disease and nerve and eye damage,” Hertzler said. “We want to see if this herb has this kind of effect.”
Salacia oblonga is still relatively difficult to find in the United States, Hertzler said, although there are manufacturers that sell the herb through the Internet.