The best supplement for lowering blood pressure is hawthorn. It works to control blood viscosity, strengthen the heart, and release pressure on arterial walls that might be compromised by heart-attack inducing inflammation. The worst supplement for controlling blood pressure is vitamin D, in pill form. Made as a copycat of Mother Nature, it can weaken the heart via calcification. Whereas, if obtained by the sun, or an all-natural cod liver oil supplement, the "nutritive D" can be an asset to cardiovascular health.