Sweet potatoes and yams

Published 3:40 pm Tuesday, November 9, 2010

Recently I was intrigued by a discussion of the nutritional and appearance characteristics of sweet potatoes and yams.

A reader in cyberspace had asked Dr. Irene’s Nutrition Tidbits (Healthandage.com) to clarify distinctions in nutrition and color of these two vegetables.

Which was more nutritious? Turns out, the facts are confusing and surprising.

Sweet potato data, as expected, shows outstanding nutritional value. They are an excellent source of fiber and Vitamin C, but are best known for their richness in Vitamin A. Vitamin A is critical in many body functions, including vision, growth, cell health and bone remodeling. In the sweet potato, Vitamin A is primarily in the form of beta-carotene, a precursor to Vitamin A, which our bodies modify into Vitamin A. It is beta-carotene which gives the sweet potato its rich orange color.

Sweet potatoes also are a fair source of Vitamin B-6 (pyridoxine), folic acid and several other essential nutrients. Sweet potatoes are a nutritional bargain for the 160 calories in a small baked sweet potato (about 1/2 cup).

References on yams show they do not contain any Vitamin A. They have roughly the same nutritional value as Irish potatoes — which isn’t at all bad. But how can it be that they lack Vitamin A, since what we see being sold as yams is often even deeper orange than sweet potatoes? The answer is that what you are buying is not a yam, but a different variety of sweet potato.

As it turns out, some years back Louisiana farmers started calling their sweet potatoes yams to differentiate them from varieties grown further north. True yams are never orange or sweet. They are an African and/or Asian crop which has a rough, dark outer skin and pale insides.

Whether you plan to have yams or sweet potatoes for the holidays, it probably will be a sweet potato, an excellent and delicious addition to your diet during the holidays.

They are available all year round as well, but those in the market at this time of the year and are the freshest and most nutrient-packed.

Angela Treadaway is a regional extension agent with the Shelby County Extension Service. She can be reached by e-mail at TREADAS@aces.edu.