Difference Between Yams and Sweet Potatoes
True yams and sweet potatoes are completely different plants. What Americans call 'yams' are actually a variety of sweet potato with orange flesh. Real yams are starchy tubers from Africa and Asia with rough, bark-like skin and white or purple flesh. Sweet potatoes are sweeter, moister, and more nutritious than true yams.
Key Takeaways
- In the United States, the confusion began when orange-fleshed sweet potatoes were introduced alongside the traditional white-fleshed variety.
- In international or specialty grocery stores, you may find true yams labeled correctly.
- Canned 'yams' in American stores are almost always sweet potatoes.
Explanation
In the United States, the confusion began when orange-fleshed sweet potatoes were introduced alongside the traditional white-fleshed variety. To distinguish them, producers labeled the orange ones 'yams,' though botanically they are all sweet potatoes (Ipomoea batatas).
True yams (Dioscorea species) are native to Africa and Asia and are rarely found in typical American grocery stores. They are starchier and drier than sweet potatoes, with rough brown skin that looks like tree bark. They can grow very large, sometimes exceeding 100 pounds.
Sweet potatoes come in many varieties with flesh colors ranging from white to orange to purple. The orange-fleshed varieties (often mislabeled as yams) are particularly nutritious, high in beta-carotene, fiber, and vitamins. All sweet potatoes are botanically unrelated to regular potatoes.
Nutritionally, sweet potatoes and true yams differ substantially. A medium sweet potato (about 130g) provides 438% of the daily value of vitamin A as beta-carotene, 37% of vitamin C, and 4 grams of fiber. A comparable portion of true yam delivers only 2% of vitamin A but 27% of vitamin C and 20% of the daily value of potassium. True yams also contain about 40% more calories per serving due to their higher starch content.
The USDA actually requires that any sweet potato labeled as a "yam" in U.S. stores must also include the term "sweet potato" on the label. Despite this regulation, many shoppers remain confused. At international markets, Caribbean stores, and West African groceries, you can find genuine yams—they look distinctly different, with cylindrical shapes up to 5 feet long, rough bark-like skin, and firm, starchy white flesh that tastes more like a regular potato than a sweet potato.
Things to Know
- In international or specialty grocery stores, you may find true yams labeled correctly.
- Canned 'yams' in American stores are almost always sweet potatoes.
- Japanese sweet potatoes and purple sweet potatoes are distinct varieties, not yams.
- True yams contain a compound called diosgenin that was historically used in the synthesis of early contraceptive hormones—this has no effect when eaten as food but is a notable botanical distinction.