Yams are actually a variety of sweet potato which we grow in the US. A true yam is imported, and isn't as attractive as what we call yams and buy in our super markets. The true yam isn't as orange as what we purchase in the US. That orange color is Beta Carotene, which can be converted into Vitamin A.
Potassium is a mineral that helps to control blood pressure. In the Dietary Approaches to Stop Hypertension (DASH) study, one study group ate servings of fruits, vegetables and low-fat dairy food in place of snacks and sweets. This approach offered more potassium, magnesium and calcium. After eight weeks, this group lowered their blood pressure by an average of 5.5 points (systolic) over 3.0 points (diastolic). Yams also contain a storage protein called Dioscorin. Preliminary research suggests that Dioscorin can help your body to achieve increased kidney blood blow thereby reducing blood pressure.