Department of Agriculture requires labels with the term "yam" to be accompanied by the term "sweet potato." Unless you are specifically searching for yams, which can be found in international markets, you are probably eating sweet potatoes. African slaves began calling the soft sweet potatoes "yams" because they resembled the yams they knew in Africa. When soft varieties were first grown commercially, there was a need to differentiate the two kinds. Why the confusion? According to the Library of Congress website Everyday Mysteries, sweet potato varieties are classified as either "firm" or "soft." In the United States, the firm varieties came first. They are also starchier and drier than sweet potatoes. Yams are native to Africa and Asia, and there are more than 600 varieties. Sweet potatoes are members of the morning glory family, while yams are closely related to lilies and grasses, according the Harvard T.H. Sweet potatoes and yams are often used interchangeably in recipes, but in fact the two vegetables are not even related. This side effect should decrease if you cut down on sweet potato consumption.Īccording to the Mayo Clinic, people with a history of kidney stones may want to avoid eating too many sweet potatoes, as the vegetable contains oxalate, which contributes to the forming of calcium-oxalate kidney stones.
"While there aren't any severe health problems associated with sweet potatoes, they are high in vitamin A, which the body stores," Flores said. "When levels get too high, you may notice your skin and nails looking a little orange." They may also cause some skin-related side effects. Previous research has shown a link between a high-GI diet and type 2 diabetes. (The glycemic index (GI) refers to how quickly and how much a food raises a person's blood sugar after eating.) White potatoes, on the other hand, are a high-GI food, with a GI of 78. Sweet potatoes are considered a medium glycemic index food, according to HSPH, with a glycemic index of 63. Scientists are studying both of these compounds for their role in human health and disease preventions, HSPH says. Two "phytochemicals" in sweet potatoes are responsible for their bright color: Beta-carotene (a pre-cursor to vitamin A) gives orange sweet potatoes their orange flesh, and anthocyanins give purple sweet potatoes their purple hue, according to HSPH. They also contain no fat, are relatively low in sodium and have fewer calories than white potatoes - although they do contain sugar. Sweet potatoes are also high in vitamin C, potassium and fiber, according to HSPH. Sweet potatoes are packed with vitamins: They "are high in vitamin A, vitamin B5, B6, thiamin, niacin, riboflavin, and, due to their orange color, are high in carotenoids," said San Diego-based nutritionist Laura Flores. Cooking sweet potatoes with the skin on also helps prevent the loss of nutrients, including vitamin C and beta-carotene. Boiling sweet potatoes retains more beta-carotene, and makes this nutrient easier for the body to absorb, HSPS says.