Sweet Potato vs Yam

Now that I have to watch out for oxalates (those crystals that can form in one’s kidneys that give you kidney stones, and believe me, you DON’T want those!) I have to be careful of the kind of foods I consume. Before I got my first AND second kidney stones in so many months back in the Spring, I was pounding down baby lettuce mixes, spinach salads, and cooked spinach in omelettes, thinking I was being very healthy for myself. After all, spinach is full of good nutrients, right? And ordinarily, it would have been healthy, had I only known I was prone to kidney stones. And yes, they are genetic, but no one in my family ever had them, so how was I to know?

But as an example, Romaine lettuce has zero grams of oxalates per serving, while raw spinach has 656 mg per serving! Yikes! And cooked it has 755 mg! Who knew? All that iron and vitamins. And it was attacking me and I didn’t even know it. So now, they are simply out as part of my diet.

Because of our upcoming Thanksgiving holiday, I was naturally taking a look at sweet potatoes and yams, because the holiday table didn’t seem complete without them. Sweet potatoes have a moderate amount of oxalates (11-29 mg per serving, a serving in this case being 1/2 cup) while yams were high in oxalates at 30 mg or more per half cup serving, with a whopping 40 mg. And believe me, every mg counts.

And then I got to thinking. Do I know what a yam is or a sweet potato? Aren’t they the same thing?

Well, my goodness no! They are two entirely different things.

First, sweet potatoes. Look at the variety above! They aren’t part of the potato family which are the Nightshade family (sounds scary, right? but that only means they are related also to tomatoes. Tomato/potato) but are instead from the morning glory family, or Convolvulaceae. Weird how botanicals propagate and change, isn’t it? They are found in Central and South America and can have white to orange to purple flesh. And as the name implies, they do have natural sugars and are sweet!

On the other hand, a yam is an African tuber, NOT a potato either, nor a morning glory, and have a bark sort of look on the outside and white and starchy on the inside and are definitely NOT sweet, and belong to the lily and grass family. And most likely, you’ve never seen these in your grocery store unless you go to a speciality store. They can be long and tree-limb-like too. Sweet potatoes can have a light, tan skin, and white interior, but other sweet potatoes have a reddish skin and orange interior. These both might be in your regular supermarket. And guess what? Even those canned “yams” you might have been using for years, are most certainly sweet potatoes, not yams at all.

I know you’ve all seen these cans in the supermarket. And look at this confusing label. It used to be simply sold as YAMS. But there it is in big letters, “CUT SWEET POTATOES” But right below that it says “CUT YAMS IN LIGHT SYRUP.” What the heck, Princella???

Why this confusion? Marketing. The orange-fleshed sweet potatoes with the fun shapes (I always liked to point them out to my son when he was little–they look like seals, birds, etc), were introduced to the U.S. market in the early part of the 20th century. The people who produced them and those that shipped them used the term “yam” (for some reason) to differentiate them from the white-fleshed variety already out there in grocery stores. I guess labeling was too tough for them back then? But farther back in the history of this country, enslaved Africans referred to the local sweet potatoes as “yams” because they reminded them of their staple of real yams in their homeland. “Yam” is a West African term, though Americanized. The real term is “nyami,” “nyam,” or “nyambi,” which mean “to taste” or “to eat”.Is one more nutritious than the other? No. They would be the same nutritionally (except for slightly more sugars in the sweet potato).

So the next time you sit down to dinner with your candied sweet potatoes with the browned marshmallows on top, know that they aren’t yams at all, and love them anyway for what they are. Because likely, you’ve really never eaten a yam in your life.