Whole Food Plant-Based doctors explain that sweet potatoes are under-recognized superfoods! Pigmented sweet potatoes are nutritionally better! Purple sweet potatoes — also known as Okinawan sweet potatoes or 'ube' — are the best!

Traditional Okinawans are one of the 'Blue Zones' populations. They traditionally got a large percetage of their calories from sweet potatoes. Okinawa Diet (Wikipedia) explains, "Okinawans in 1950s ate sweet potatoes for 849 grams of the 1262 grams of food that they consumed, which constituted 69% of their total calories."

The Wikipedia article cites this paper: Caloric Restriction, the Traditional Okinawan Diet, and Healthy Aging by Bradley J Wilcox, D Craig Wilcox, Hidemi Todoriki, Akira Fujiyoshi, Katsuhino Yano, Quimei He, J David Curb, Makoto Suzuki, published in Annals of New York Academy of Sciences, Vol 1114, Issue 1, pages 434-455, October 2007.