Much ado about sweet potatoes and their commonly confused root-vegetable relative, the yam. Both are everyday kitchen staples for adding texture, taste, and nutrients to dishes, but they are not the same. The punchline? One is a potato, and one is not.
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Yams and sweet potatoes: both delicious, both vegetables, and both rich in vitamins and minerals, but they are not the same piece of produce. Professional and home chefs love them for their hearty texture. But they are, in a word, different.
Their names are often used interchangeably, leading many to believe they’re eating yams when chowing down on a sweet potato. Grocery stores often mislabel them as well, which makes the whole debacle even more confusing. So, let’s clear a few things up.
What is a yam?
Yams are indigenous to Africa and Asia and come from the plant species called dioscorea. Varieties within this plant family include dioscorea rotundata (white yam), dioscorea cayenensis (yellow yam), dioscorea bulbifera (potato yam), dioscorea esculenta (Lesser yam), dioscorea alata, (Ube or purple yam), and dioscorea polystachya (Chinese yam or nagaimo). I found them extremely difficult to find, except for nagaimo, which is at my local Asian market.
They have rough brown skin and texture, not unlike what you typically see on a yucca or russet potato. Their flesh is very light and pale. They won’t yield a sweet flavor like sweet potatoes when cooked. You’ll find that yams have a more neutral flavor that can make other seasonings and ingredients the real star of a dish. They take on the taste of the elements around them.
Despite their flavor differences, you can cook yams similarly to sweet potatoes: boiled, roasted, fried, and baked. They can be used in stews and soups or anytime you’re braising meat. They tend to shine most when boiled or braised.
What is a sweet potato?
Ipomoea batatas is the scientific name for sweet potatoes, coming from the dicotyledonous plant in the morning glory family. You are likely to find some sweet potatoes labeled as yams at the store. There are three common types:
- Orange sweet potatoes have purple or copper skin and orange flesh, and many consider them to be the most traditional. Their flesh becomes sweet when cooked.
- White sweet potatoes have light brown skin with pale flesh. Appearance wise, they look the most like yams. There is also an Oriental/Japanese variety with a dark purple skin and white flesh that is sweet and nutty.
- Purple sweet potatoes have purple flesh and skin that’s been described as dusty and tan in color (still, with a hint of purple).
When you hit the kitchen with sweet potatoes, you can bake them, boil them, mash them, braise them, and roast them. The fact that they are used in similar ways to yams is part of what hitches these two vegetables at the hip.
What is the difference between them?
While yams and sweet potatoes are the same in their application, they differ in taste, texture, and appearance. Sweet potatoes live up to the ‘sweet’ in their name, while yams are more earthy and neutral. Yams have a lot of the same starchiness as traditional potatoes, while sweet potatoes can be softer and gooier. Yams may also have less of a tapered point, something that’s more pronounced in sweet potatoes.
Some of the confusion around yams and sweet potatoes stems from the fact that there are multiple types of sweet potatoes. Many are still labeled as yams even though they are actually potatoes. There’s the classic, orange-fleshed potato we tend to cook into sweet potato casserole and top with marshmallows around the holiday season. However, white sweet potatoes have a pale flesh that resembles a yam.
A little history
If you dig deep into the history of yams and sweet potatoes, you’ll learn that enslaved Africans often used sweet potatoes in place of yams, which were a symbol of home, after they were shipped to America.
Another possible factor in the close association between yams and sweet potatoes is that sweet potato growers are said to have adopted the name yam to distinguish their beloved veggie from regular potatoes. Now, the names are used interchangeably so much. It’s proven challenging to shake the term yam when talking about sweet potatoes and vice versa.
Selection and storage
Both yams and sweet potatoes should be firm without soft spots or cracks. While some texture on the skins is normal, anything that borders soft or wrinkly may signal that the product is past its prime. For sweet potatoes specifically, look for bright colors.
Store sweet potatoes in a cool (not refrigerated), dark place, and they should last a month. When stored at room temperature, that window may shrink to about a week. Yams are also best stored in a cool, dry place and best eaten within a few weeks. At room temperature, they will last 5-7 days. Once cut, use them both within 24 hours.
How do you use them in dishes?
Both lend themselves to many types of dishes. Use sweet potatoes to whip up anything from sweet potato puree for baking to fries to sauteed sides or a substitute for traditional baked potatoes. They stand up well to all cooking methods. Roast yams for an earthy side with savory spices, or braise them with your next pot roast.
Which is healthier?
Nutrient-wise, purple sweet potatoes may pack the biggest punch; studies have shown they have more antioxidants and soluble fiber. When comparing yams to sweet potatoes, sweet potatoes can come with lower calorie content. They also have more vitamin C and beta-carotene (the orange-fleshed variety specifically).
Boiling sweet potatoes is the best way to retain their beta-carotene, and if you cook them with their skins on, it helps to preserve more of the nutrients. The skin, in general, will deliver more nutrients than not eating the skin.
1 cup of raw yams contains: 177 calories, 2.3g protein, 0.255g fat, 41.8g carbohydrates, 6g fiber, 0.75g sugar, 25mg vitamin C, 25.5mg calcium, and 31mg magnesium
1 cup of raw sweet potatoes contains: 114 calories, 2.09g protein, 0.067g fat, 26.7g carbohydrates, 3.99g fiber, 3.19mg vitamin C, 39.9mg calcium, and 33.2g magnesium