Hypertension is abnormally high blood pressure (140/90 -- "140 over 90" -- or higher). Where it has no know cause it is called essential hypertension. When a disease or other physical problem is the cause of high blood pressure, the condition is called secondary hypertension. Virtually all chronic hypertension is essential hypertension.
Hypertension (high blood pressure), is a major cause of stroke and a risk factor for coronary disease.
Normal (optimal) blood pressure is 120/80 or 110/70. In this measurement 120 mm Hg (millimeters of mercury pressure) is the systolic, or pumping, pressure. 80 mm Hg is an average diastolic, or resting, pressure. As either or both pressures rise, the heart and blood vessels work harder to pump the blood throughout the system.
There are many dietary and other factors that distinguish populations without hypertension from those in which hypertension exists. The isolated groups in whom blood pressure does not rise with age also tend to have a low energy intake. The relationship between energy consumption and blood pressure is obscure, but a reducing diet that leads to weight loss is associated with a substantial fall in blood pressure, measured as intra-arterial pressure. A reduction in total energy consumption can therefore reduce blood pressure and this may partially explain the fall in cardiovascular mortality in populations with impaired food supplies, such as in the Netherlands in the Second World War.
In 2001, approximately 27% of the adult population in the USA suffered from high blood pressure. Over 30 percent of those were unaware of their condition and less than 25 percent were taking medication to help lower their pressure.