Sweet Potato Variety Provides Successful Dietary Approach in Type 2 Diabetes Control in Clinical Trial

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  • Caiapo (Ipomoea batatas)
  • Diabetes
  • Date: October 15, 2004 HC# 050444-266

    Re: Sweet Potato Variety Provides Successful Dietary Approach in Type 2 Diabetes Control in Clinical Trial

    Ludvik B, Neuffer B, Pacini G. Efficacy of Ipomoea batatas (Caiapo) on diabetes control in type 2 diabetic subjects treated with diet. Diabetes Care. 2004;27(2):436-440.

    Type 2 diabetes is caused by insulin resistance and impaired insulin secretion. Treatments include diet, exercise, medications, and insulin. A white sweet potato, called Caiapo (Ipomoea batatas), cultivated in the mountains of Kagawa Prefecture in Japan and eaten as a traditional food for treatment of anemia, hypertension, and diabetes, has been developed as a nutraceutical product in recent years and is consumed and sold as a supplement for the prevention and care of type 2 diabetes. A preliminary study in men with type 2 diabetes found that Caiapo (4 g/day for 6 weeks) lowered the total and LDL cholesterol levels and lowered blood glucose by increasing insulin sensitivity without affecting insulin secretion. The objective of the present study was to verify the findings of the preliminary study and to increase the number of participants and the study duration.

    Sixty-one patients with type 2 diabetes treated by diet only participated in this placebo-controlled, randomized, double-blind study. Patients consumed Caiapo 4 g/day or placebo once a day for 12 weeks. Blood glucose, cholesterol, triglycerides, and HbA1c (a measure of long-term glucose control) were monitored.

    HbA1c significantly decreased after 2 and 3 months of treatment with Caiapo compared to placebo (P<0.001). Both groups had significant weight loss and statistical analysis could not rule out the possibility that weight loss contributed to the improvement in HbA1c. Fasting blood glucose decreased in both groups, but to a greater degree in the Caiapo group (P = 0.03). After 3 months of treatment, 48.3% of the patients consuming Caiapo had mean fasting blood glucose levels below the upper normal limit compared to 7.7% of those in the placebo group. Blood pressure did not change. At the end of treatment, cholesterol levels in the Caiapo group where significantly lower than those in the placebo group (P<0.05). There was no significant effect on triglyceride levels. Caiapo was well tolerated. Adverse events were minimal but were mainly gastrointestinal.

    This study confirmed the beneficial effects of Caiapo on glucose and serum cholesterol levels in type 2 diabetic patients. The study also showed for the first time an improvement in long-term glucose control. However, the exact contribution of weight loss on the effects observed was not quantified. The authors hypothesize that since glucose levels continued to decline when the weight loss had stabilized, Caiapo had an effect on glucose beyond that caused by weight loss. Caiapo may have increased the body's sensitivity to insulin. Caiapo-induced improvement in insulin sensitivity would not be responsible for the decrease in cholesterol levels. Therefore, an unidentified compound could be responsible for the cholesterol-lowering effect.

    The authors conclude that Caiapo aids in the management of type 2 diabetes. Often the final conclusion of an HerbClip is that the primary study needs to be verified in a second study or that a larger N is needed. However, these were accomplished in the present study. Considering that this study confirms the findings of the preliminary study, has a larger N, and was well conducted, the authors' conclusions warrant attention.

    —Heather S. Oliff, Ph.D.

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