The people of Okinawa are the longest lived people in the world. What is their secret? The purple sweet potato.
The last 20 years of nutritional research has revealed that it is not enough to simply avoid bad things like sugar and fat. Rather it is important to consume as many good things as possible, like vitamins, minerals, and antioxidants. Thus every time we eat something with little or no vitamins, we are missing a chance to be healthier.
The problem is that human beings need energy and most diets around the world are built upon staple foods that are rich in energy but low in vitamins, such as bleached wheat flour or white rice. Chemically enriching wheat flour, as is done in the United States, does not help that much, and while potatoes or brown rice are a bit better than wheat or white rice, they still have pretty low vitamin-to-calorie ratios, compared to vegetables.
Enter the sweet potato. The sweet potato is a great source of carb-based energy, but it also has a nutrient profile more like a vegetable than a grain or a regular potato. If you can use sweet potatoes as your staple, you are going to get some tremendous health benefits in terms of reduced rates of cancer, diabetes, and other nasty diseases.
But as good as sweet potatoes are, the purple sweet potato is the king of them all. Loaded with even more B-vitamins and antioxidants, it is just about the healthiest food you could possibly eat. And this is the food the Okinawans used as their staple crop until recent decades, which is a major reason why there are so many centenarians on Okinawa.
And all of this is not to mention that the purple sweet potato is incredibly easy to grow, is environmentally friendly in terms of its impact on the land, is incredibly versatile in terms of culinary uses, and is the tastiest of all the sweet potatoes. My wife compares it to eating ice cream. You should definitely give it a try.