Starchy and sweet, the yam has its own unique mouthfeel and flavor even though it is so often confused with the sweet potato.
Typically, when you peruse the produce market shelves you will find sweet potatoes and yams all piled together and sometimes the yam is indeed called a sweet potato and vice versa, however, the yam and sweet potato are not botanically related. Yams are more closely related to lilies and grasses, technically, they would be more closely related to a grain than they are to the potato. Yams are the tuberous root part of a very interesting spade leaved plant. To me, a yam feels almost stringier when chewing, as if I can feel the starch fibers. True yams seem to be native to Africa and Asia, although they have made their way around the world into appropriate climates and cultivated agriculture. They come in a wide variety of shapes, sizes, and even colors which is just one more thing that adds to the confusion of identifying them appropriately.
From a culinary perspective, yams while often interchangeable with the sweet potato, yams to have their own unique properties. They tend to be higher in starch and have less moisture content, if you’re working with a recipe that might be impacted by these differences then you will want to adjust. Otherwise, yams can pretty much be enjoyed anyway that a sweet potato can, except raw. Most yams have a significant amount of naturally occurring toxins and so require cooking to make them more palatable and easier to digest with no repercussions. The Japanese yam is one of the few true yams that can be eaten raw.
From a nutritional perspective, yams possess different nutritional properties than sweet potatoes. There has been quite a bit of interesting research conducted on the Yam Tuber Mucilage (YTM) which is basically the liquid that rises to the surface when you cut a yam open and let it sit out for a few minutes.
If you slice a yam and let it sit, you will see a milky looking substance bead to the surface. That substance contains some pretty amazing qualities. One of the first is allantoin; which is a featured ingredient in medications that fight the herpes virus. Applying the YTM milk to ulcers, cold sores, and other virus related skin issues has been a common practice in traditional medicine for centuries, and now we know why. Allantoin wipes out the virus while at the same time stimulating the healthy part of the cell to regenerate. There are other chemical compounds found in YTM that inhibit the angiotensin enzyme. Angiotensin contributes to vasoconstriction, which can, if out of balance, elevate blood pressure and increase the potential for blood clots and heart issues.
Yams are a good source of vitamin C and B and a wide variety of minerals like potassium, iron and manganese. They are also high in fiber and belly friendly fructo-oligosaccharides (lovingly known as ‘olies’). Eating your olies helps your gut friendly bacteria stay strong and healthy, giving them the edge over any invaders that might want to take over and cause your gastrointestinal tract distress.
The next time you’re in the produce section sorting through the tubers, it could be worth asking specifically for a real yam, just to see if you can notice the difference and also to reap the benefits of this often misidentified food.