An Okinawa imo may not sound too appetizing, but you might like a tasty dish of purple sweet potatoes. Actually, they are one and the same. Purple sweet potatoes, sometimes called Hawaiian or Okinawa sweet potatoes, or simply imo, are native to Okinawa and served regularly on the island. Okinawa is known as the longevity capitol of the world, and imo might be one of the reasons. Imo is packed with healthy nutrients, and in 2010, Dr. Mehmet Oz named purple sweet potatoes as one of his five super foods for the year.
Anthocyanins
The most powerful antioxidants are phytochemicals. And it is one phytochemical, anthocyanins, that gives purple sweet potatoes their distinctive pigment. It also is responsible for the red, blue and purple hues in other fruits and vegetables, including blueberries, red grapes and red cabbage. Purple sweet potatoes have 150 percent more antioxidants than blueberries. In fact, sweet purple potatoes have higher antioxidant properties that either vitamin C or vitamin E. The anthocyanins in imo make it a potentially potent weapon against cancer. In addition, cooking imo doesn't dilute its antioxidant properties.
Dietary Fiber
Imo has more to offer than antioxidants. You get 4 g of fiber in each cup of purple sweet potatoes, and just 140 calories. As MayoClinic.com explains, dietary fiber lowers the risk of heart disease and diabetes by lowering cholesterol levels and blood glucose levels. It can aid in weight loss by making you feel satiated sooner. And it may have some anti-cancer effects, although to date the evidence is mixed.
Glycemic Index
Unlike other forms of potatoes, purple sweet potatoes have a low glycemic index. While other potatoes have healthy attributes, some nutritionists caution people to avoid them, since the high glycemic index of most potatoes can spike blood sugar levels. The low glycemic index of imo makes it a healthy food for everyone, including diabetics, who have to closely monitor their blood sugar levels.
Designer Imo
In June, 2011, researchers at Kansas State University announced that they had created a "designer" purple sweet potato with both a purple skin and purple flesh. Since it is the purple pigment that contains anthocyanins, the new strain of imo contains an even larger quantity of the antioxidant. This follows studies of anthocyanins in 2005 and 2009 in Japan that indicated the antioxidant has potent anti-cancer properties. The official color of the sports teams at Kansas State is purple, so it seems fitting that the designer purple sweet potato has been created there as well.
References
- Hawaii Pride: Hawaiian Sweet
- The Dr. Oz Show; 5 Superfoods To Eat Now; February 2, 2010
- "The Telegraph"; Purple Sweet Potato 'New Superfood to Prevent Cancer; Aislinn Simpson; July 17, 2011
- "Bioscience, Biotechnology and Biochemistry"; Prevention by Natural Food Anthocyanins; M. Kano, et al; February 2002
- "The Journal of Toxilogical Sciences"; Antioxidant Activity of Anthocyanins; A. Hagiwara, et al; May 2005
- MayoClinic.com; Dietary Fiber: Essential for a Healthy Diet; November 2009
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