Nutrients

One cup of sweet potatoes supplies 950 milligrams of potassium, and a cup of yams contains 911 milligrams, which is about 20 percent of the 4,700 milligrams you should get each day. Potassium keeps your heart beating normally and helps your muscles work right. A serving of sweet potatoes supplies 1,922 micrograms of vitamin A, a nutrient that keeps your eyes, skin, teeth and bones healthy. This is more than the 700 to 900 micrograms you need on a daily basis. Yams contain vitamin A, but a serving only supplies a trace amount. Sweet potatoes and yams contain vitamin C and iron, two nutrients that you need for a strong immune system, and folate, which can prevent certain birth defects.