Perspectives Online

Researchers reveal sweet potato as weapon against diabetes


Sweet Potatoes

As healthy food goes, it's hard to beat the sweet potato. Packed with important vitamins like A, C and B6, sweet potatoes have good antioxidant properties. They're also an excellent source of dietary fiber, potassium and iron. Now, recent research in the College of Agriculture and Life Sciences has confirmed that sweet potatoes are a low-glycemic index (GI) food, which could be good news for diabetics.

The glycemic index measures how quickly certain foods release carbohydrates into the body. High-GI foods cause blood sugar levels to spike, while low-GI foods release glucose slowly into the bloodstream.

Dr. Jon Allen, CALS professor of food science; Dr. Van Den Truong, USDA-ARS food scientist and assistant professor of food science at N.C. State; and Dr. Masood Butt, a visiting scientist and associate professor from the University of Agriculture in Pakistan, along with students and other scientists, conducted a study that confirms the recognized low GI of sweet potato.

The team also discovered that the Beauregard variety of sweet potatoes - which makes up about 85 percent of the production in North Carolina - has essentially the same protein patterns as a commercial dietary supplement known as Caiapo, marketed to control blood glucose in diabetics. Developed by Japanese scientists, Caiapo is derived from the peel of white-skinned sweet potatoes, which have been consumed in Japan for many years as a remedy for anemia, hypertension and diabetes.

The researchers found that the protein content of the flesh of the Beauregard sweet potato was higher than that of the peel. This suggests that the entire vegetable could play a role in lowering blood glucose in diabetics: the peel, as processed into a nutritional supplement like Caiapo; and the flesh, as a simple addition to the everyday diet.

"With further research in this area, it may be possible to recommend that people with diabetes or insulin resistance consume sweet potatoes or use extracts of North Carolina sweet potato to help control blood glucose," Allen says in the project report. "This therapy should cost less than conventional drugs, and it may have fewer side effects."

As the study enters its next phase, the big question now is whether or not the hypoglycemic (low-GI) properties of sweet potatoes can survive the high temperatures required for cooking and baking, Allen says.

The study is funded by the North Carolina Sweet Potato Commission, the Higher Education Commission and the Government of Pakistan, where collaborators conducted similar research on sweet potato varieties grown in that country.

"We're hoping that diet, particularly the consumption of sweet potatoes, will become a more widely used tool in the treatment of diabetes," Allen says. "It has the potential to be more cost-effective than drugs."

- Suzanne Stanard