Sweet potatoes and yams are a Thanksgiving staple for many families, which makes it important to understand one key fact: Sweet potatoes are not the same thing as yams.

The terms are often used interchangeably, but they come from different families; sweet potatoes are edible roots from the morning glory family, and yams are edible tubers from the lily family.

Sweet potatoes pack significantly more vitamin A and carry a much sweeter taste. Both vegetables can be boiled or roasted, though sweet potatoes are commonly prepared in other ways, such as fries, pies and even soup.

"There are pros and cons to both of them," said Cathy Nonas, a clinical dietitian and former professor at Icahn School of Medicine at Mount Sinai in New York City. "I definitely think either one is a great choice over a white potato; both of them have more fiber than a white potato and lots of vitamins."

For example, 1 cup of baked sweet potato with skin has 769% of the daily value of vitamin A, far more than the amount found in yams (3%) or in white potatoes (1%). Vitamin A can improve vision, reproduction and the immune system – and it helps the heart, lungs and kidneys function properly. A cup of sweet potatoes also contains 6.6 grams of fiber, or 26% of the daily value. That's compared with 5.3 grams in yams and 6.3 grams in white potatoes.

Orange and purple sweet potatoes are especially good sources of antioxidants, and laboratory research suggests they might help combat certain types of cancer. Lab research has also linked the antioxidants in sweet potatoes to better gut health.

Studies also have found sweet potatoes may help reduce bad cholesterol in people with Type 2 diabetes. People who are likely to develop kidney stones may want to use caution when eating sweet potatoes because they contain oxalates, which may increase the risk.

There are many ways to add sweet potatoes to your diet, including chips (thinly sliced, then baked), fries (cut into wedges and baked) and mashed with milk or seasoning. Preparing sweet potatoes with healthy oils, such as olive oil, may help you absorb more beta carotene, which has strong antioxidant effects.

"It's so pure that it's one of the first things that you feed babies when they're first starting out on solid food," said Nonas, a former senior adviser at the New York City Health Department who is the founder and executive director of the nonprofit Meals for Good. "You feed them a mashed-up, plain sweet potato. And that's for good reason."

Sweet potatoes also keep well. So, if you buy some for Thanksgiving and decide not to bake them, you can still prepare them closer to Christmas. "These things are great roasted with a little bit of olive oil and salt in the oven, and as they brown, they get really toasty and delicious," Nonas said.

During the holidays, though, they often are prepared as a casserole – with marshmallows and sugar – or as a pie.

"You obviously reduce the nutritional value of it because all of a sudden you also ate all of the bad fat," she said. "As an optimist at Thanksgiving and Christmas and all of these holidays, I try to take advantage of the sweet potatoes for their taste. But as a nutritionist, I always try to make them as healthy as possible."

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