Yams

Yams are a good source of vitamins B6 and C and the minerals potassium and manganese, as well as dietary fiber. Vitamin B6 is instrumental in breaking down homocysteine, lowering the risk of heart attack. The potassium and fiber in yams help control blood pressure. Yams have a lower glycemic index than true potatoes.
Some types of yams contain a steroid, diosgenin, that has been used by the pharmaceutical industry to synthesize human hormones, including cortisone, estrogen, and progesterone, but the body has not been shown to convert this steroid on its own. Still, there are some intriguing hormone connections. In studies on rats, the starch from Chinese yams has shown promise in reducing the levels of cholesterol and triglycerides in the blood.
Nutritional Facts :
One-half cup of baked yams provides 79 calories, 18.8 g carbohydrate, 1 g protein, 0.1 g fat, 2.7 g dietary fiber, 8 mg vitamin C, 11 mcg folic acid, 456 mg potassium, 5 mg sodium, 33 mg phosphorus, 10 mg calcium, and 12 mg magnesium.