Sweet Potato or Yam: Which Vegetable is on Your Thanksgiving Menu?

Sweet Potato or Yam: Why Does This Healthy Vegetable Have So Many People Confused?

Sweet potatoes have been part of the typical Thanksgiving menu for a century or more, although neither they nor regular everyday potatoes were present at the first Thanksgiving feasts on either side of the border. If you grew up in the United States, you probably remember eating candied yams or sweet potato casserole topped with marshmallows alongside your turkey and cranberries.

If you grew up in the American south, you may have also eaten sweet potato pie at Thanksgiving for dessert – instead of pumpkin pie. (And that rivalry between sweet potato pie and pumpkin pie is the stuff of a whole ‘nother conversation!)

Here in Canada, these dishes are not nearly as common as they are in the United States but sweet potatoes are still one of our Thanksgiving sides – usually just baked and served with a pat of butter. We also eat sweet potatoes with our Christmas dinner, and pretty much any other time we cook a turkey with all the trimmings. In fact for many Canadians, these are probably the only times in the year that we eat a sweet potato, more’s the shame!

But is it a Sweet Potato or a Yam?

The question of whether we’re actually eating a sweet potato or a yam is a confusing one. Let me share a personal experience with you to illustrate what I mean. Thanksgiving is celebrated in early October here in Canada, so we had our big turkey dinner a little over a month ago. And as every year, there was a bowl on the table filled with small, foil-wrapped nuggets still steaming from the oven.

“Do you want sweet potatoes?” my mother asked as she held the bowl out towards me. “Well, they’re really yams.” she added. “I made sure to get yams instead of sweet potatoes.” She then went on to explain that the yams were smaller, sweeter, and softer when cooked than sweet potatoes are. And they have a darker-coloured flesh.

Well, this was news to me!

 

 

Why was Mom Calling Sweet Potatoes, ‘Yams’?

In all my 50 years on the planet, we’ve never called those lovely, orange-fleshed tubers “yams” in our family. And I generally see this vegetable sold as “sweet potato” in the stores. Most of my friends call them sweet potatoes too, so I had always kind of assumed that “sweet potato” was more of a Canadian expression, while our American neighbours seem to prefer “yam.” (There is, of course, a completely unrelated African tuber properly called a yam, that has been available in North American grocery stores for several years now. If you’ve ever had those yams, you know they are very different from a sweet potato, whatever we choose to call it in Canada and the US.)

So why was Mom suddenly calling our sweet potatoes “yams”? And why was she talking about there being some sort of difference in the size, colour, and firmness of the flesh?

Sweet potato (not a yam)
Note the smooth skin and tapered end of the sweet potato
(Image: LauraLisLT/Pixabay/CC0 1.0)

 

What is a Sweet Potato?

The scientific name for the sweet potato is Ipomoea batatas. If you’re familiar with botanical names for popular flowers, you might recognize that sweet potatoes are related to morning glories. In fact, the resemblance between the flowers of the two plants is remarkable. Could you tell one from the other if you saw these two plants growing side by side?

The flower of a sweet potato plant
The sweet potato is one vegetable you might want to grow just for the flowers!
(Image: Deborah Hayes/Public Domain Pictures/CC0 1.0)

 

A morning glory flower looks very similar to the sweet potato flower
This second flower is a morning glory. Could you tell them apart?
(Image: ccipeggy/Pixabay/CC0 1.0)

 

Sweet potatoes are a New World vegetable. They were first domesticated about 5,000 years ago, probably in Central America. But today they are grown throughout much of the Americas. They are also cultivated in some parts of Africa, in India, China, and other Asian nations, and also in Polynesia and Australasia.

Although the common name implies that these are potatoes, the sweet potato is only distantly related to potatoes. The potato belongs to the nightshade family (Solanaceae,) along with tomatoes, peppers, and eggplant. The sweet potato belongs to the morning glory family (Convolvulaceae.) Both families are members of the order Solanales. That makes the two root vegetables sort of distant cousins. Sweet potatoes are also not related to yams, which are tubers in the family Dioscoreaceae. The yam is an Old World vegetable native to Africa and Asia, and is more closely related to grasses and lilies than to either potatoes or sweet potatoes.

 

 

What Does a Sweet Potato Look Like?

Sweet potatoes have tapered ends and smooth, thin skin. The skin can range in colour from copper or brown to red or even purple. The flesh of a sweet potato is usually orange, varying in saturation from deep orange all the way to yellow or beige. Sweet potatoes can also have white or purple flesh.

A sweet potato showing the deep orange flesh inside – just remember the colour can vary!
Sweet potatoes come in a wide range of colours – including purple!
(Image: National Cancer Institute/Wikimedia Commons/public domain)

 

By contrast, yams have coarse, scaly skin that is sometimes compared to a tree trunk. They are cylindrical tubers, usually with white flesh. Some North American grocery stores stock African yams, but you’ll probably need to go to an import store or specialty market unless you live in a big city.

The yam is an Old World vegetable and is completely unrelated to sweet potatoes
This yam has a coarse, bark-like skin and a more tubular shape than a sweet potato
(Image: chrisad85/Pixabay/CC0 1.0)

 

Why Do We Sometimes Call Sweet Potatoes Yams?

There seem to be two main reasons for the use of the word “yam” when we are actually talking about sweet potatoes:

  1. African slaves used this name:
    Yams are one of the staple foods in Africa. West African people saw a resemblance between yams and sweet potatoes, so they used the same word for both vegetables. Some accounts say Europeans introduced sweet potatoes to the people of West Africa, who later came to the New World as slaves. Other stories say the slaves first encountered sweet potatoes once they’d arrived in America. As the slave trade was carried on for some three centuries, it’s likely both are true. In any case, the West African people used sweet potatoes the same way they did yams, and they used the same name for both.

  2. Farmers in Louisiana used this name:
    All sweet potatoes originally had white or pale yellow flesh. So darker-fleshed sweet potatoes were a pretty cool development! Farmers in Louisiana had a sweeter, orange-fleshed variety of the sweet potato in about the 1920s or 1930s. Because you can’t tell what the inside of a vegetable looks like from its skin and you don’t know how sweet it is until you eat it, they needed to find a clever way to set their sweet potato apart from the rest.

    The farmers called their vegetable a “yam,”  sweet potatoes. The Louisiana crops contrasted with the drier, firmer fleshed sweet potatoes that farmers elsewhere in the US were growing. This is why you’ll sometimes see people using “yam” to describe a sweet potato that has soft, moist, richly coloured flesh, and “sweet potato” for those vegetables whose flesh is firm, dry, and often more pale in colour.

Although we all have our preferences when it comes to the type of sweet potatoes we like to eat, you should know that the “yam” type of sweet potato is better suited to some recipes and the more firm, dry-fleshed sweet potato is better for others. Sweet potatoes that are softer are great for baking, mashing, and of course making a sweet potato casserole or baking a sweet potato pie. But those with a firmer flesh will make great sweet potato fries.

Sweet Potato Nutrition

Some folks say that the sweet potato is a superfood. If you look at its nutritional content, it’s not hard to see why. One average sweet potato, baked in its skin, contains 438% of our recommended daily intake for vitamin A – a nutrient that about half of North Americans are lacking in their diet. 

Sweet potato also scores high for several other nutrients: 37% of vitamin C; 27% of potassium; 25% each of vitamin B6 and manganese; 15% each of vitamin B6, potassium, and dietary fibre; 10% of thiamine (vitamin B1.) Sweet potatoes also supply lesser amounts of magnesium, iron, calcium, phosphorus, zinc, sodium, several additional B vitamins, and protein. Wow!

Baking Increases Vitamin C in Your Sweet Potato

Baking is a preferred cooking method for sweet potatoes, as it increases the vitamin C content of the vegetable. If you prepare it by a different method, you won’t get as much of the vitamin C but it’s still a nutritious vegetable. One baked sweet potato provides 103 calories (compared with 163 calories for a medium baked potato or 174 calories for 1 cup of potatoes mashed with whole milk.)

If you are eating sweet potatoes for their vitamin A and carotenoid content, choose those with the richer orange colour to their flesh. If you decide to experiment with purple sweet potatoes you’ll benefit from anthocyanins, the same flavonoids found in blueberries. White-, cream-, or yellow-coloured sweet potato flesh contains mostly beta-zea-carotene.

When it’s time to eat that turkey dinner, choose a baked potato and other high-fibre vegetables. Eat these and a healthy portion of turkey before you move onto other foods and drinks. Research shows that eating lean protein and high-fibre vegetables at the beginning of your meal can reduce both blood sugar and insulin levels, compared to consuming foods like bread or fruit juices first.

Healthy living tip: Eat high-fibre veggies & lean protein first – 24 Carrot Diet
Avoid holiday weight gain: Eat lean protein and high-fibre vegetables like sweet potatoes at the beginning of your meal
( Graphic made in Canva using a public domain image by Pixabay user LauraLisLT)

 

Do you include sweet potatoes in your Thanksgiving dinner sides? Or “yams”? How does your family like to serve them? Please share your traditions in the comments below. And to all my American readers who will be celebrating with family this week, Happy Thanksgiving!

 

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Sweet potato or yam: do you know the difference? Whether you call them yams or sweet potatoes, the vegetables in your Thanksgiving sides are probably New World sweet potatoes and not Old World yams. | food history | sweet potato nutrition | 24 Carrot Diet
Sweet potatoes come in a wide range of colours, from cream or yellow through deep orange. There are even purple sweet potatoes!
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Graphic made in Canva using a public domain image by Pixabay user LauraLisLT

 

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Original content © 2017 Kyla Matton Osborne, aka #RubyWriter

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38 thoughts on “Sweet Potato or Yam: Why Does This Healthy Vegetable Have So Many People Confused?”

    1. And those of us who only ever heard them called “sweet potatoes” growing up always wondered what the heck yams were! I think I was in my mid-40s before I actually saw one in the grocery store.

  1. To confuse the issue further: what is it they have Japan!? They call it sweet potato in English, but it looks nothing like Sweet Potato at home. But then Sweet Potato isn’t native to Ireland and it is only imported in the last 20 years, just as I had moved to Japan! So my introduction to sweet potato / yam was in Japan. It is really popular here and I happen to live in an area famous for sweet potato and thus sweet potato flavoured treats. You can get sweet potato flavoured ice-cream even!
    Great post and I love that you provided so much detail especially about nutrition.

    1. Oh my! I see where that complicates things! If I’m on the right track, you’re referring to either Dioscorea japonica or Dioscorea polystachya. The former is sometimes known as “Japanese yam” in English. Are these what you’re referring to?

      There is also another vegetable called “Japanese Sweet Potatoes” but it seems that one is actually Ipomoea batatas. I’d love to know which one(s) you’ve come across there and what they taste like!

  2. I had never even heard of a yam until I was grown and had moved away from my NC home. And I never knew that you could cook them any other way than baking and serving with butter.
    🙂

    1. That’s pretty much my experience too, Nikki. We never heard them called anything but sweet potatoes when I was growing up. And never ate them any other way but baked. I started to hear about sweet potato casserole and sweet potato pie because of American movies and TV, but it was just a reference in passing. I was 20 before I had sweet potato pie. I got a recipe and made it for myself, just to see what it was like. Never knew about candied yams or the whole marshmallows on top of the sweet potato casserole until much later.

  3. Okay, I’m totally embarrassed to tell you that I have spent 47 years thinking that sweet potatoes and yams were the same things! I just thought maybe some people called them sweet potatoes, and some referred to them as yams–kinda like the potAtoe poTOHtoe thing! I learn something new every day!! 🙂

    1. You’re certainly not alone, Kristi! I thought it was just a preference thing until a few years back when I discovered the African yams at the grocery store 🙂

    1. I would imagine that yams sold in Australia are the African sort, so they would avoid using that label for any other vegetable.

  4. Great post, love the insight! I’m always confused between the two (and now pretty convinced my grocery store is confusing the two as well 🙂

    1. It seems that in the United States, it’s still a practice to label some types as sweet potatoes and others as yams, despite them being the same vegetable. Perhaps if the African yam becomes popular, we’ll see a change in that!

    1. I’d love to hear more about how you prepare sweet potatoes, Blair. We really grew up just eating them baked with the holiday turkey. And they often weren’t available to us except around the holidays. Now that they are more accessible year round, I would like to start finding some different ways to incorporate them in our diet. I need a few more ideas, besides sweet potato fries and sweet potato-bean burgers, LOL!

    1. I love sweet potatoes too. I tried true African yam once and did not enjoy it. One day, I’d like to have it prepared by someone who knows what they’re doing. I think I might like it better that way 🙂

    1. Do you mean white yams, as in African yams with white flesh? Those definitely exist, though they aren’t as easy to find in North America. There are also white-fleshed sweet potatoes. You might want to try them with your hubby, if that’s what you got. They are drier than the sweet potatoes some folks call yams, and I found they were less sweet. I didn’t care for them baked. But I think they’d be lovely roasted, boiled, or made into baked sweet potato fries.

    1. I like the sweeter & softer ones too, Sondra. Of course, they’re all sweet potatoes, even though that particular type is marketed in the US as “yams.” 🙂

  5. I actually love both but I probably purchase sweet potatoes more often because locally they’re more abundantly available. I cook them frequently with seafood dishes. I am excited though to find and experience purple sweet potatoes 🤗

    1. You are the second person to mention cooking sweet potatoes with fish or seafood. That’s a combo that I’ve never tried. I really must, though. It sounds good 🙂

      If you try the purple sweet potatoes, please let me know what you think. I haven’t been able to get any of those yet. I’ve had the white ones, but I think they were not prepared the best way. I will have to try them again, but this time roasted, fried, or maybe boiled instead of baked.

  6. I never knew that sweet potatoes were such a super food and rich in Vitamin A. Love it when I learn something new LOL. I personally am not a fan of them, something to do with the texture but sister-in-law always brings them to dinner and they are a hit. She makes a casserole and tops them with marshmallows and cranberry jelly.

    1. My youngest has the same issue with the texture of the sweet potatoes, Tina. We favour the softer, sweeter type and I’ve been wondering if she might like the more firm ones better. Have you tried both types? Maybe you’d also enjoy the firmer ones better. Try sweet potato fries or sweet potatoes roasted with other root vegetables. You might find you enjoy those!

  7. I had no idea there was such a difference between the two. we always called them “Yams” in my family but they were definitely just sweet potatoes. Now that I know the difference I don’t think I have ever had an actual yam. I’m interested in trying one and will look next time I go to a food specialty store.

    1. The one and only time I tried a real yam, I went grocery shopping with a friend and we decided to buy some to try. They were huuuge and we didn’t know what we were going to do with them, so I think we only bought one or two. We found a recipe online for a very basic preparation and followed the instructions. But by the time the yam was supposed to be cooked, it was still hard as a rock. We finally managed to get it soft enough to eat, but it smelled absolutely disgusting. Of the eight of us eating dinner together that night, he and I were the only ones brave enough to try the yam. And we both thought it tasted rotten. I mean, literally, spoiled. I have no idea whether we bought a bad yam or whether we ruined it when we cooked it. But it was totally gross!

      If you manage to find a real yam and cook it properly, please let me know. I want to be encouraged to brave them again, LOL!

  8. Thank you for explaining this difference. I always thought they were different because they are marketed differently and those marketed as sweet potatoes are usually more expensive. We enjoy them often with our salmon dinners, as well as with poultry.

    1. I heard about that pricing difference in the US. I haven’t noticed it here, though sweet potatoes are always a pricey item.

      I must try sweet potatoes with salmon. That will be a new flavour combo for us 🙂

    1. you were fast to find this post, Carol! I just added it a little bit ago. I love sweet potatoes too. They’re probably my favourite Thanksgiving side, though I love my cranberries too 🙂

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