Yams are a good source of both potassium and vitamin B6, two nutrients that your body needs every day. Vitamin B6 helps your body break down a substance called homocysteine, which can cause damage to blood vessel walls. High intakes of vitamin B6 have been shown to reduce the risk of heart disease.
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 flow thereby reducing blood pressure.
In addition, Yams' complex carbohydrates and fiber deliver the goods gradually, slowing the rate at which their sugars are released and absorbed into the bloodstream. Because they're rich in fiber, yams fill you up without filling out your hips and waistline. Yams are also a good source of manganese, a trace mineral that helps with carbohydrate metabolism and is a cofactor in a number of enzymes important in energy production and antioxidant defenses.