Yams

Yams are one of carbohydrate rich, staple tuber vegetables of west african origin. Botanically they belong to the family dioscoreaceae, in the genus, dioscorea.athere are several hundred cultivars of dioscorea exist; however, only few of them worth of commercial important. Some ofapopular yam tubers grownaare dioscorea rotundata (white guinea), d. Alata (yellow), d. Bulbifera (aerial), d. Opposita (chinese), d. Esculenta (southeast asian) and d. Dumenterum(trifoliate).besides their use as food, yams have been symbolically associated with culture, and ritualism all over africa, asia, and latin americas.

The yam plant is a perennial vine cultivated for its large, edible,aunderground tuber, which can grow up to 120 pounds in weight and up to 2 meters in length. They are one of the typical tropical crops requiring hot, humid temperatures and may cease to grow when temperature dips below 68 degrees f. Yams are similar in appearance to sweet potatoes, however, they are not at all related to it. Important differences that distinguish them from sweet potatoes; yams are monocotyledons, larger in size, features thick, rough, dark brown to pink skin depending up on the cultivar type. Whereas sweetpotatoes (ipomoea batatas) are dicotyledonous, relatively smaller in sizeand possess very thin peel. Although the tuber is grown throughout africa, nigeria is the worldas largest producer, and exporter of yams, accounting for over 70 percent of the world total output.

Yam is a good source of energy; 100 g provides 118 calories. Its crunchy edible part chiefly composed of complex carbohydrates and soluble dietary fiber.adietary fiber helps reduce constipation, decrease bad (ldl) cholesterol levels by binding to it in the intestines and lower colon cancer risk by preventing toxic compounds in the food from adhering to the colon mucosa. Additionally, being a good source of complex carbohydrates, it regulates steady rise in blood sugar levels, and, for the same reason, recommended as low glycemic index healthy food.a

The tuber is an excellent source of b-complex group of vitamins. It provides adequate daily requirements of pyridoxine (vitamin b6), thiamin (vitamin b1), riboflavin, folic acid, pantothenic acid and niacin. These vitamins mediate various metabolic functions in the body.

Fresh root also contains good amounts of anti-oxidant vitamin; vitamin-c. Provides about 29% of recommended levels per 100 g. Vitamin c has some important roles in anti-aging, immune function, wound healing, and bone growth.

Yam contains small amounts of vitamin-a, and beta-carotene levels. Carotenes convert to vitamin a in the body. Both these compounds are strong antioxidants. Vitamin a has many functions like maintaining healthy mucus membranes and skin, night vision, growth and protection from lung and oral cavity cancers.

Further, the tuber is indeed one of the good sources of minerals such as copper, calcium, potassium, iron, manganese, and phosphorus. 100 g provides about 816 mg of potassium. Potassium is an important component of cell and body fluids, which helps controlling heart rate and blood pressure by countering hypertensive effects of sodium. Copper is required in the production of red blood cells. Manganese is used by the body as a co-factor for the antioxidant enzyme, superoxide dismutase. Iron is required for red blood cell formation.