Yams are tropical, tuber vegetables native to West Africa but also grown in southeastern United States from Louisiana to Georgia. As tubers, yams grow underground to a size of between two to six feet long and a weight of 11 to 33 lbs., and according to JRank, an online science encyclopedia, resemble a very large and elongated potato. In addition to their value as a food, yams also contain a steroid chemical called diosgenin, commonly used as an ingredient in birth control pills.
Carbohydrate Composition
According to the online food nutrition database Nutrient Facts, a 150 g, or 1-cup serving of raw, cubed yams contain 40 g of carbohydrates, including 6 g of dietary fiber. Although a glycemic load of 13 indicates yams contain a moderate percentage of carbohydrates, its glycemic index of 37 is low, indicating yams will have only a small effect on blood sugar levels and are a good choice for weight control.
Nutrition
In addition to its value as a low glycemic food, a 1-cup serving of yams is a good source of vitamin B1, also called thiamine, important in carbohydrate metabolism and to ensure proper functioning of the heart, muscles and nervous system. Yams also contain vitamin B6, necessary for proper functioning of your immune and central nervous system, blood oxygenation and blood sugar management. Vitamin C helps protect cells from damage due to cell oxidation and assists in wound healing, and folate is important in cell production and to help prevent anemia. In addition, yams provide calcium, zinc, riboflavin, magnesium, iron, niacin and phosphorous, in amounts of less than 10 percent.
Benefits
Ayurvedic medicine lists additional health benefits of yams that include relief from menstrual cramps, hormone regulation, preventing nausea during pregnancy, a natural muscle relaxant and a natural cure for stomach acidity and irritable bowel syndrome.
Consideration
Of the over 150 varieties of yams, some contain a high percentage of alkaloid chemicals that are poisonous if you eat them raw. According to Practically Edible, an online food encyclopedia, toxic yams are most often the bitter tasting varieties. To be safe, do not eat raw yams. Instead, prepare them by boiling, mashing, braising, grilling, roasting, baking or frying.
Misconception
Yams are different from sweet potatoes. In fact, as the U.S. Library of Congress notes, they do not even belong to the same family. Yams are a monocot, or single seed plant from the Dioscoreaceae family, while sweet potatoes are a dicot, or double seed plant from the Convolvulacea family. An easy way to tell the difference is by size. According to Practically Edible, most yams are too large to sell whole in a grocery store. As a result, you will most often see yams cut up, packaged and sold by the pound, rather than in bulk, as you will find with the smaller sized sweet potato.
References
- JRank Science Encyclopedia: Yam
- Nutrient Facts: Yam, Raw
- Harvard Health Publications: Glycemic Index and Glycemic Load for 100+ Foods
- University of Wisconsin Center for Integrative Medicine: Glycemic Index
- National Institutes of Health: Thiamine
- National Institutes of Health Office of Dietary Supplements: Vitamin B6
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