Tuesday, March 02, 2010

Potato, Sweet Potato and Yam Throwdown

Shortly after posting my piece on Sweet Potatoes and Yams, I was enjoying a non-paleolithic adult beverage with Toby - locally known as, "The Man". He said that he enjoyed the post, but that he would have liked to have seen tables, data, percentages and such. Basically, he wanted me to geek out, but also to bring in a "normal" potato into the mix for comparison. James, while eating his order of "sweet potato" fries also jumped into the mix, noting Vitamins and a whole host of other things for me to geek out on.

Hence, this post.

We each discussed what we thought were sweet potatoes and yams, then James started telling tales of tuber colors and grilling. Googling for such images is rather confusing, given the US's inability to name/advertise their tubers correctly. For clarification, when I buy a sweet potato and a yam from Henry's, this is what I buy:

The sweet potato is on the left, and the yam is on the right.

When cut, the insides look like this:

Note the orange color for the yam. For any of you who get sweet potatoes with your meal, or get the frozen ones - both of which are typically orange - I'd be skeptical!

Referencing nutritiondata.com, I present to you, internet blog readers, the following (all data is per 100 grams of the tuber):

Glycemic Load (lower is better)
* Potato: 8
* Sweet Potato: 8
* Yam: 12

Inflammation Factor (the higher the number, the more anti-inflammatory [desirable])
* Potato: -46
* Sweet Potato: 123 (Good!)
* Yam: -73

Nutrient Balance (Higher is better)
* Potato: 51
* Sweet Potato: 55
* Yam: 45

CHO breakdown (Total/fiber/starch/sugar, in grams)
* Potato: 18.4/2.2/15.4/0.8
* Sweet Potato: 20.1/3/12.7/4.2
* Yam: 27.9/4.1/~/0.5 (Although I think the ~, which I interpreted to be 0, is incorrect. However, that data point is irrelevant).

Vitamins (Vitamins and %'s worth noting)
* Potato: C @ 33%, B6 @ 15%
* Sweet Potato: A @ 284%, B6 @ 10%
* Yam: C @ 28%, B6 @ 15%

In my opinion, the sweet potato is the supreme tuber choice of the three, since it is tied for lowest glycemic load, won in a landslide of anti-inflammatory properties, gets a slight nod to the nutrient balance, and with a high vitamin content primarily in Vitamin A (a strong anti-oxidant, score!)

7 comments:

jameson said...

don't think it's that simple... because i think the "yam" you bought could actually be a sweet potato.

"Yams in the United States are actually Sweet Potatoes with relatively moist texture and orange flesh. Although the terms are generally used interchangeably, the US Department of Agriculture requires that the label "yam" always be accompanied by "SweetPotato.""

http://www.foodreference.com/html/art-sweet-potato-yam.html

"The misnamed yam and sweet potato often give one an idea of the type of sweet potato one is actually going to serve. For example, the garnet yam (actually a sweet potato) is often considered one of the most delightful, and is noted for its very sweet taste and deep orange color."

http://www.wisegeek.com/what-is-the-difference-between-a-yam-and-a-sweet-potato.htm

"The sweet potato has yellow or orange flesh, and its thin skin may either be white, yellow, orange, red or purple. Sometimes this root vegetable will be shaped like a potato, being short and blocky with rounded ends, while other times it will be longer with tapered ends. There is often much confusion between sweet potatoes and yams; the moist-fleshed, orange-colored root vegetable that is often called a "yam" is actually a sweet potato."

http://wiki.answers.com/Q/What_is_the_difference_between_a_sweet_potato_and_a_yam

Tawnee said...

I totally agree that sweet potatoes are the best choice, but I also agree with James that they do come in different colors, shapes, etc., from what I've read.

Usually I stick with the white-ish ones just to be sure it's a SP and not Y.

But I also get the bag of "sweet potatoes" from Trader Joe's and they are orange-ish, the same as the yam on this post. So is TJ's wrong? Or are they right and that's just another variety of sweet potato? The TJ sweet potatoes taste a lot different than my white SPs.

Confusing. ugh. Glad I'm not the only one who's into this issue haha

Kim said...

dropped over from Tawnee's blog.

Hmpf. Every "sweet potato" i have bought has looked exactly like the yam in your picture.

im confused!

IAN said...

So to be safe, is a good rule of thumb that if it is white or purple it is a SP and if its orange it could be a yam?

Ryan Denner said...

Wow. Amazing. I think I nearly opened up a can of worms with this post.

I was at TJ's last night, and yeah, I saw the bag of "Sweet Potatoes" that totally looked orange.

Additional research on the subject has made things more confusing.

gunnbr said...

Wow! I was gonna say "Thanks for the great post!", but now after reading the other comments, I'm even more confused than before. :(

polyhex said...

Both of the tubers pictured are definitely sweet potatoes.

Yams are an unrelated and MUCH larger tuber common in Africa (they can grow 8 feet long! Mole rats live inside them!) You are unlikely to find true yams in the US except at ethnic markets.

It is likely that the reason orange sweet potatoes are sometimes called "yams" in the United States is that slaves called them "yams" because they reminded them of the tubers they enjoyed in Africa.

From Wikipedia: "In the United States, sweet potato (Ipomoea batatas), especially those with orange flesh, are often referred to as "yams." In the United States, firm varieties of sweet potatoes were produced before soft varieties. When soft varieties were first grown commercially, there was a need to differentiate between the two. African slaves had already been calling the soft sweet potatoes "yams" because they resembled the yams in Africa. Thus, soft sweet potatoes were referred to as yams to distinguish them from the firm varieties.[9] Sweet potatoes labeled as "yams" are widely available in markets that serve Asian or Caribbean communities."

Hope that helps.