Red yams are sweet potatoes. What grocery stores in the United States sell as “red yams” are almost always a variety of sweet potato called Garnet, which has dark red-orange skin and deep orange flesh. True yams are an entirely different plant, native to Africa and Asia, and rarely found in American supermarkets.
Why the Names Got Mixed Up
Sweet potatoes and true yams aren’t even close relatives. Sweet potatoes belong to the morning glory family and are native to Central and South America. True yams belong to the family Dioscoreaceae, a group of over 600 tropical species native to Africa and Asia. The two plants evolved on different continents and share no meaningful botanical connection. They just happen to both grow underground.
The word “yam” likely comes from West African languages, arriving in the Americas through Portuguese and Spanish trade routes. When orange-fleshed sweet potato varieties became popular in the U.S. during the mid-20th century, producers needed a way to distinguish them from the drier, white-fleshed sweet potatoes already on the market. They borrowed the word “yam,” and it stuck. The USDA now requires that any sweet potato labeled “yam” in retail must also include the word “sweet potato” somewhere on the label, but shoppers often miss the fine print.
What “Red Yams” Actually Are
The sweet potato most commonly sold as a red yam is the Garnet variety, sometimes called the Red Garnet. It has dark red-orange skin and deep orange flesh with a high moisture content. When cooked, Garnets become soft and velvety, with a flavor that blends mild earthiness and sweetness. This moist, creamy texture is a big part of why they became the default “yam” in American kitchens, especially for holiday dishes like casseroles and pies.
Other orange-fleshed varieties like Jewel and Beauregard sweet potatoes are also sometimes labeled as yams, though Garnets are the ones most often marketed specifically as “red yams” because of their distinctly dark skin.
How to Spot a True Yam
If you’ve never traveled to West Africa, the Caribbean, or parts of Asia, you may have never seen a real yam. True yams look nothing like what’s in the Thanksgiving casserole. They have rough, bark-like brown skin that’s scaly and thick, surrounding starchy white flesh (occasionally purple, depending on the species). They can grow enormous, sometimes several feet long and weighing over 100 pounds. The texture when cooked is dry and starchy, closer to a regular potato than to a sweet potato.
You can sometimes find true yams at international or Caribbean grocery stores in the U.S., usually sold in chunks because of their size. If the label just says “yam” at a standard American supermarket, you’re almost certainly looking at a sweet potato.
Nutritional Differences
Sweet potatoes, including the red-skinned Garnet variety, are rich in beta-carotene, the pigment responsible for their orange flesh. Your body converts beta-carotene into vitamin A. True yams contain very little beta-carotene because their flesh is mostly white.
The two also differ in how they affect blood sugar. True yams vary widely by species: boiled white yams have a glycemic index around 44, making them a lower-glycemic starchy food, while boiled yellow yams come in much higher at about 75. Sweet potatoes generally fall in the low-to-moderate range, typically between 44 and 61 when boiled, depending on the variety and cooking time. Both foods are good sources of fiber, potassium, and complex carbohydrates, but they aren’t nutritionally interchangeable.
Cooking With Red-Skinned Sweet Potatoes
Garnet sweet potatoes shine in recipes that benefit from moisture and natural sweetness. Their high water content means they break down easily when baked or roasted, making them ideal for mashing, pureeing into soups, or folding into baked goods. They caramelize well at high oven temperatures, developing crispy edges while staying creamy inside.
If a recipe specifically calls for a drier, firmer sweet potato, look for a white or Japanese variety instead. And if you’re following a recipe from West African, Caribbean, or Southeast Asian cuisine that calls for yam, the dish likely means the real thing. Substituting a Garnet sweet potato will give you a completely different texture and flavor profile, since true yams are starchy and neutral while Garnets are sweet and soft.