Start with a healthy, varied diet. It has been medically proven that
potassium helps to prevent and control high blood pressure. Be sure to
get enough potassium in the foods you eat. Some good sources are
various fruits, vegetables, dairy foods, and fish. Magnesium can also
help guard against cardiovascular disease and lower high blood
pressure. Evening Primrose, Garlic and Yarrow are all said to have an
effect in controling blood pressure.
In addition there is a very good .gov guide to lowering high blood
pressure here:-