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What's the Difference Between a Sweet Potato and a Yam?

Although the terms are often used interchangeably in America, sweet potatoes and yams are two different vegetables:

• Sweet potatoes are a starchy tuber native to the Americas that is distantly related to a potato. Sweet potatoes in the US come in two varieties: one with a creamy, white interior and the other with an orange interior.
• Yams, on the other hand, are a tuber native to the tropical regions of Africa and Asia. They generally have darker, bark-like skin on the outside and vary in color on the inside from creamy white to purple. They contain no starch.

Simple, right? So why the confusion?

Going back to Colonial times, African slaves called the sweet potato a yam after the familiar tuber in Africa. This confusion was institutionalized by the USDA who started labeling the darker variety of sweet potato 'yam' to distinguish is from its paler cousin. Thus, the orange sweet potatoes are often sold as 'yams,' but the USDA requires them to also contain 'sweet potato' (which is what they really are) in the labeling.

Nutritional Data

Nutritional Analysis

As you can see from the nutrition data above, sweet potatoes, yams, and potatoes have a very similar nutritional profile. This is not surprising given, that they are all tubers of one kind or another. Where sweet potatoes do have an edge, however, is that they are moderately anti-inflammatory, given the higher amounts of Omega-6 fatty acids and manganese (an essential trace mineral to maintain the integrity of skin and bone). This is particularly important for people who may be managing chronic illness or high-level athletes.

Both Are Great Alternatives to Potatoes

Whether you opt for a sweet potato or a yam, either make a great alternative to potatoes. Because both have more natural (albeit different) flavor than a russet potato, they are less likely to require additives such as butter, sour cream, or excess salt to make them taste good. However, because they usually require a longer cooking time (in excess of an hour), they are not the quickest thing to make for a late evening meal. However, my recipe below makes it a bit more manageable.

Simple Roasted Sweet Potato (or Yam) Recipe

This recipe reduces the cooking time by halving the sweet potato or yam and scoring it to expose the interior flesh. Combined with roasting it at a higher temperature, the result is a recipe that takes only 45 minutes rather than the usual 1 1/2 hours.

Cook Time

Ingredients

• 2 sweet potatoes or yams
• 1 tablespoon olive oil
• salt and pepper to taste
• 1/4 teaspoon nutmeg

Instructions

1. Preheat the oven to 400°F.
2. Half the yams lengthwise. Cut slits cross-wise into the interior flesh to expose it.
3. Drizzle the yam with olive oil. Add salt, pepper, and nutmeg.
4. Roast for 45 minutes or until a fork easily pierces the interior.

Tried This Recipe? Rate It.

Comments

Kathryn Grace from San Francisco on September 07, 2014:

Nicely done! Over the years of my cooking life I have read dozens of articles that purport to show one way or another how to tell the difference between sweet potatoes and yams. Several have claimed there is no difference whatsoever.

In the end, I have to rely on science for the answer, which it appears you have done as well. I thought you might like to know that two horticulturist specialists at the University of North Carolina wrote a short, definitive paper about the difference between the two vegetables, which includes a nice chart delineating the various horticultural factors. All supports your information quite nicely.

If you would like to link to their page, you can find their article, "What is the Difference Between a Sweet Potato and a Yam?" at http://www.ces.ncsu.edu/hil/hil-23-a.html.

Thank you for writing this. I have a few recipes that involve yams, er, sweet potatoes. Would you mind if I link to this page, where appropriate, when I discuss their nutritional value and origins?

Teresa Coppens from Ontario, Canada on April 01, 2013:

You have educated me. I did not know there was a difference between the two. I do know I have been cooking and eating sweet potatoes however. Not only are they great to eat but using the water used to boil sweet potatoes makes fantastic gravy!

MickiS (author) from San Francisco on March 13, 2013:

Thanks for the comment Claudia. Yams are great, but they are harder to find in the US (the sweet potato is far more common), so I hope you have more luck in Mexico.

Claudia Tello from Mexico on March 12, 2013:

The fact that yams don't have starch makes me want to eat them! I don't know why, but I never pay attention to yams when I am grocery shopping. Next time I will.

I love roasted sweet potatoes and have never tried them with nutmeg. It sounds nice in my mind so I'll try them with the additional condiment next time.

tattuwurn on March 05, 2013:

I love sweet potatoes and yam, respectively called "kamote" and "ube" here in the Philippines. Sweet potatoes can be incorporated into savory dishes to add some thickness and sweetness aside from being made into snacks. Although the sweet potatoes we're used to eating are usually having a white interior.

Yam is an amazing tuber. Here they are one of the ingredients for cakes, pastries, and ice cream. The "ube halaya" (or ube jam -- or you can call it "yam jam" just for the pun) is also a favorite. And I like its purple color. :)

I have yet to see the orange-fleshed sweet potato though. :)

Voted up and interesting, useful, awesome.

MickiS (author) from San Francisco on January 30, 2013:

Brendl, thanks for the comments.

They are both vegetables. I'm on your husband's side when it comes to not eating potatoes and sweet potatoes in the same meal! Sweet potatoes are potatoes are cousins, and they are both high in starch.

Orange versus yellow is not an indicator of yam or sweet potato, by the way.

Brendi on January 29, 2013:

I forgot to ask. Are raw sweet potatoes or raw yams toxic? I have considered making coleslaw with raw sweet potatoes(orange flesh). I have heard that there is more carotene in sweet potatoes(orange flesh) than in carrots. Is this true?

Brendi on January 29, 2013:

I love baked sweet potatoes including the skins. My husband will not eat a regular potato & a sweet potato in the same meal!!!!! They're both potatoes he says. Poor guy! Mind you he's inclined to be that way anyway. I do not & my hubby doesn't like yams (yellow fleshed) even though the grocery store calls them sweet potatoes. Aren't yams & sweet potatoes classed as a vegetable as compared to a regular white fleshed potato?

MickiS (author) from San Francisco on September 07, 2012:

Yes, the nutritional data supplied above is for a raw yam, and among the different varieties of yams, this data varies very little.

Sweet potatoes that are mistakenly labeled yams contain the nutrition data above for sweet potatoes. Like yams, the differences vary little between the varieties.

The source for the nutritional information above is the United States Department of Agriculture (USDA).

Valerie on September 07, 2012:

So, just to be clear, the nutritional information above is for a true yam, not the variety of sweet potato that is referred to as a yam, correct? If so, is the nutritional value for both varieties of sweet potato the same?

MickiS (author) from San Francisco on June 21, 2012:

Thanks for the comment, ytsenoh. You're very welcome.

Cathy from Louisiana, Idaho, Kauai, Nebraska, South Dakota, Missouri on June 20, 2012:

I always thought sweet potatoes and yams were the same thing. I also think that pumpkin pie and sweet potato pie taste very, very similar. I like it all. I do think and agree that sweet potatoes/yams are better for you than white potatoes. Thanks for your hub and recipe.

MickiS (author) from San Francisco on June 11, 2012:

Thanks. I, too, once thought that. Hence my research that inspired the Hub! LOL.

Danette Watt from Illinois on June 11, 2012:

I'm sure I'm not alone when I say that I thought sweet potatoes and yams were the same thing (hence your hub!). Good info, I liked the comparison chart, that was helpful.

MickiS (author) from San Francisco on April 18, 2012:

KoffeeKlatch Gals, I know! I think I've never really eaten a yam before even though I had been buying a tuber named as such in the store! Thanks for the comment.

Susan Hazelton from Sunny Florida on April 18, 2012:

It's definitely sweet potatoes for me. I don't believe I've even actually eaten a yam.

Simone Haruko Smith from San Francisco on April 04, 2012:

How interesting! I had kind of grouped sweet potatoes and yams in my head before reading this Hub. So far as I was concerned, they were all the same thing. I'm not much of a fan since I tend to dislike sweet things, but perhaps it's time I give yams another try. Thanks for the Hub!

MickiS (author) from San Francisco on April 04, 2012:

As I researching it, rjsadowski, I realized the same thing!

rjsadowski on April 04, 2012:

An interesting comparison. From your description, I doubt that I have ever eaten a yam.