Okinawan Sweet PotatoPosted By | Posted On Oct 29, 2008
From time to time, we hear stories concerning remote areas of the globe where unusually large numbers of people live unusually long, healthy lives. This is often attributed to diet, and, in most instances, these stories turn out to be of little merit.
Recently, I became aware of a colorful new vegetable being sold in the markets of Chinatown. A little investigation led me to yet another tale of remarkable longevity in a strange and wondrous land. This time however, there seems to be some truth to the story. The product I am referring to is known by several different names, including the Japanese sweet potato, the Imo, the purple sweet potato, and the Okinawan sweet potato.
The sweet potato is believed to have originated in Central America, and was introduced to Spain and the Philippines through Spanish explorers. From the Philippines, it made its way to China, Historical records indicate that a seedling was brought to the Japanese islands of Okinawa from China’s Fujian Province in 1605, where it quickly established itself as a miracle food. Subject to yearly typhoons that often destroyed the rice paddies, Okinawans were under constant threat of famine. The sweet potato, which was buried in the ground, survived these onslaughts, and provided a stable source of calories for the growing population. Today, the Okinawan diet, which includes liberal amounts of sweet potato, other plant foods, fish, soy products and very little meat has helped create a society that produces more centarians than any other place on the planet. This is verified by meticulously documented birth and health records kept on the islands.
The Okinawan sweet potato should not be confused with the Peruvian purple potato, which is not a sweet potato at all, but rather a regular potato that just happens to have a blue-purple skin and purple flesh. The Okinawan sweet potato on the other hand, has a light brown skin, and deep lavender flesh, and, is surprisingly sweet and extremely nutritious. The color is due to anthocyanins, which act as antioxidants. They are rich in carotenoids, saponins, flavonoids, alkoloids, and tannins, and have a high vitamin E content. They are extraordinarily high in vitamin C, and are thought to contain large amounts of dioscin, an anti-inflammatory compound. There is mounting evidence that the Okinawan sweet potato contains a significant amount of lycopene, the powerful anti-oxidant and carotenoid found in tomatoes that has been associated with a reduced risk of prostate cancer in many studies. A one- cup serving contains only 140 calories, and is packed with dietary fiber. In addition, the Chinese believe that the sweet potato is helpful in relieving the symptoms of arthritis.
In Chinatown, look for it labeled as “Japanese sweet potatoes” in the markets alongside other root vegetables and tubers such as Taro. My favorite preparation is an easy one; simply wash them but do not remove the skin, Slice them lengthwise, and place in an ovenproof baking dish. Drizzle with extra virgin olive oil, and salt, and roast them in a 400 degree oven, flesh side down until they can be easily pierced with the tip of a knife. This can take anywhere from 20 to 45 minutes, depending on the size.
If you are lucky enough to get to Okinawa, you can try them “stone-baked” and sold from “Imo trucks” which are a fixture on Okinawan street corners. However you enjoy them, you can take comfort in the fact that you are helping yourself beat the aging process with a delicious treat from a real-life Shangri-La.
Written by Jim Becker, Chinatown Guide