Thanksgiving is often a busy and stressful time to travel, but there a few ways to have a calmer travel experience.
For many families, a holiday feast doesn't feel complete without the familiar lineup of mashed potatoes and gravy, roast turkey and stuffing. Add in traditional sides like cranberry sauce, green bean casserole and warm dinner rolls, and you can practically smell the classic meal taking shape.
But for countless households, Thanksgiving or Christmas dinner doesn't truly hit that nostalgic note without a heaping scoop of what are commonly called "yams," often baked or whipped and topped with brown sugar, marshmallows or crunchy pecans. In fact, this candied dish is so woven into holiday tradition that few people ever pause to ask what they're actually eating.
So here's what yams really are, how they differ from sweet potatoes and why it's probably best to enjoy both in moderation.
What are yams? What are sweet potatoes?
While yams and sweet potatoes both grow underground, they come from different botanical families and have distinct cultural histories.
True yams belong to the Dioscoreaceae family and originated in Africa and parts of Asia thousands of years ago. They have "a rough, bark-like skin that is not usually eaten," says Ambrazia Sublett, a Philadelphia-based culinary medicine dietitian for the non-profit organization Vetri Community Partnership. They also have a starchy flesh that can be white, yellow or purple. These vegetables are typically harvested in late fall and winter and are commonly boiled, pounded, fried or stewed.
Though beloved across many regions, "true yams are relatively rare in the U.S. and are usually only found in international or specialty markets," says Jen Messer, a registered dietitian and president of the New Hampshire Academy of Nutrition and Dietetics.
Sweet potatoes, meanwhile, "come from the Convolvulaceae (morning glory) plant family," notes Messer, and originated in Central and South America. They're widely available in U.S. grocery stores year-round, but are especially common during the fall harvest.
Their skin ranges from tan to deep copper and is "smooth, thin and completely edible," says Messer; with flesh that's either orange, white or purple. Sweet potatoes "are sweeter, have a creamier texture and are naturally sweeter and softer than yams," says Sublett. Such a flavor profile makes them popular for their versatility: roasted, mashed, baked or blended into casseroles and showing up in everything from fries to breakfast hashes to holiday sides.
Why do people think yams and sweet potatoes are the same?
"In the United States, the terms sweet potato and yam are used interchangeably, but they're botanically distinct and are not the same vegetable," says Messer. The confusion dates back to the early and mid-20th century when orange-fleshed sweet potatoes were marketed as "yams" to distinguish them from firmer, pale-fleshed varieties.
The name stuck so much that today, "the U.S. Department of Agriculture requires anything labeled 'yam' to also say 'sweet potato,'" says Messer. This requirement is meant to help consumers realize that the two vegetables are distinct. "Even the 'red garnet yam' variety are actually sweet potatoes," Messer adds.
Are yams and sweet potatoes good for you?
No matter which option you prefer, you're going to get a mouthful of important nutrients when you eat either sweet potatoes or yams. "Neither vegetable is 'better,' as each offers its own benefits," says Messer.
Sweet potatoes, for instance, are particularly rich in beta-carotene, the orange pigment your body converts into vitamin A. "Vitamin A is very important to aid in vision, a healthy immune system, healthy skin and a healthy heart," says Messer. Sweet potatoes also supply vitamin C, which helps with tissue growth and repair, iron absorption and collagen formation. "Sweet potatoes also provide a good amount of dietary fiber that helps feed and increase favorable gut bacteria and supports a healthy microbiome," says Messer. Fiber is also essential for digestive health, blood sugar regulation and "is what gives you that satiated feeling after eating," says Sublett.
"And sweet potatoes contain resistant starch, which, in moderate amounts, fuels the colon, supports digestive health and may help reduce the risk of colorectal cancer," adds Messer.
True yams provide many of the same nutrients, including fiber and many of the same vitamins and minerals. They also contain vitamin B6, which supports brain health and nervous system function. "And yams tend to have a lower glycemic index, meaning they raise blood sugar more slowly which is something that may be helpful for people managing diabetes," adds Messer.
Purple varieties of both yams and sweet potatoes "are especially rich in antioxidants and phenolic compounds that may help slow the growth of cancer cells and may also support recovery after exercise," says Messer.
"Both yams and sweet potatoes also contain potassium, which is important for blood pressure regulation and cardiovascular health," adds Sublett.
Can you eat too many yams or sweet potatoes?
Despite their many benefits, it's still possible to overdo it with either vegetable. Because both are rich in carbohydrates, for instance, large portions can cause blood sugar spikes, especially for people with insulin resistance or diabetes. And while their high fiber content is generally a plus, eating too much too quickly can lead to bloating, gas or general digestive discomfort.
And because both yams and sweet potatoes are high in starch, they can cause rapid increases in post-meal glucose, contribute to excess calorie intake when eaten in excess and leave some people feeling sluggish afterward.
People with chronic kidney disease, or those taking beta-blockers or potassium-sparing diuretics, may also need to moderate their intake of high-potassium foods like sweet potatoes and yams.
How these vegetables are prepared matters, too. Sweet potatoes are often transformed into fries by being cooked in oil or made into rich casseroles made with heavy cream and sugar. And the holiday dish commonly called "candied yams" (which are actually sweet potatoes) are typically topped with marshmallows, brown sugar, butter and sometimes even syrup. "These ingredients, of course, increase the calorie, saturated fat and added sugar content of the vegetable," says Messer.
In the end, though, "both yams and sweet potatoes are a great staple to a healthy diet," Messer says. "To capitalize on their health benefits, focus on preparing them in their simplest form and serving them without added sugars and saturated fats."