Here is where I share my thoughts, ideas and opinions about the world of nutrition, food and health. I hope you find good sense, helpful guidance and inspiration to eat great healthy food that makes you feel good.

I write regularly for GI News, an online newsletter for 60,000+ Australasian and International subscribers interested in the glycemic index (GI) and associated health topics such as diabetes, weight loss and a healthy heart. It’s a great read.


11 Mar 2021

Yams are not sweet potatoes

Posted by 2142 2142 on Thursday, March 11, 2021

Living in Australia, my exposure to the celebration of Thanksgiving was through the American TV shows I watched growing up. I know turkey plays a central role on the thanksgiving table, but I also know candied yams are a traditional side-dish. As thanksgiving is coming, it got me thinking about yams, as I don’t think I’ve ever eaten them.

But wait, I’ve eaten sweet potato and isn’t that the same thing? No. Although the terms are used interchangeably in North America, sweet potatoes (ipomoea batatas) and true yams (Dioscoreaceae) are different things altogether. Although they are both root vegetables (tubers), they aren’t even in the same botanical family. Yams are part of the lily family. Candied yams enjoyed at Thanksgiving aren’t yams at all but sweet potato.

Most yams are grown in Africa and they’re also native to Asia. Yams are cylindrical and come in different sizes, including some that can be up to 25kg each! The most common African species have dark brown, rough skin and white (Diascorea rotundata) or yellow flesh (diascorea cayennensis). The white yam was (diascorea alata) first cultivated in Asia and is known as uhi in Hawaii. The Chinese yam is Diascorea polystachya.  In New Zealand and Polynesia Oxalis tuberosa are referred to as yams, or Oca in Spanish and only 2-3 cm long.

Yams are starchier and drier than sweet potato and typically ground into a paste known in Africa as Iyan, but they can be cooked in many ways. Most yams need to be cooked as eating them raw can cause illness. Boiling, frying or roasting are common, and similar to other starchy vegetables they provide a neutral base on which to serve savoury or sweet dishes. If you’d like to give them a try, find them at specialty greengrocers and perhaps make this African Yam Stew or Yam fries.

Nutritionally yams have high water content, are low in protein, virtually fat-free and contain around 27% carbohydrate of which all is starch. They are a good source of potassium, fibre and also contain vitamin B6 and vitamin C. The yellow flesh varieties are loaded with carotenoid antioxidants. The glycemic index (GI) varies by species. The common African species are medium to high GI, while the New Zealand and Chinese species are low GI.

New Zealand yams (Oxalis tuberosa)