NIH - Medical Encyclopedia: Essential hypertension "Essential hypertension refers to high blood pressure with no identifiable cause. ...Usually, high blood pressure has no symptoms at all. That is why it is often called the 'silent killer.' "

NIH - High blood pressure (Hypertension) (Medical Encyclopedia) “Blood pressure readings are measured in millimeters of mercury (mmHg) and usually given as 2 numbers. For example, 140 over 90 (written as 140/90). • The top number is your systolic pressure, the pressure created when your heart beats. It is considered high if it is consistently over 140. • The bottom number is your diastolic pressure, the pressure inside blood vessels when the heart is at rest. It is considered high if it is consistently over 90. Either or both of these numbers may be too high. Pre-hypertension is when your systolic blood pressure is between 120 and 139 or your diastolic blood pressure is between 80 and 89 on multiple readings. If you have pre-hypertension, you are more likely to develop high blood pressure at some point. … Most of the time, no cause is identified. This is called essential hypertension. High blood pressure that results from a specific condition, habit, or medication is called secondary hypertension. Too much salt in your diet can lead to high blood pressure. Secondary hypertension may also be due to: • Adrenal gland tumor • Alcohol poisoning • Anxiety and stress • Appetite suppressants • Arteriosclerosis • Birth control pills • Certain cold medicines • Coarctation of the aorta • Cocaine use • Cushing syndrome • Diabetes • Kidney disease, including: o Glomerulonephritis (inflammation of kidneys) o Kidney failure o Renal artery stenosis o Renal vascular obstruction or narrowing • Migraine medicines • Hemolytic-uremic syndrome • Henoch-Schonlein purpura • Obesity • Pain • Periarteritis nodosa • Pregnancy (called gestational hypertension) • Radiation enteritis • Renal artery stenosis • Retroperitoneal fibrosis • Wilms' tumor “

NHS - Blood pressure (high) “Causes of high blood pressure There are two types of high blood pressure: • essential (or primary) high blood pressure - where there is no identifiable cause, and • secondary high blood pressure - where high blood pressure is the result of an underlying cause, such as kidney disease, or a particular type of medication that you are taking. Essential high blood pressure While the cause of essential high blood pressure remains unknown, there is compelling evidence to show that there are number of risk factors which increase your chances of developing the condition. These risk factors include: • age - the risk of developing high blood pressure increases as you get older, • a family history of high blood pressure - the condition seems to run in families, • being of Afro-Caribbean or South Asian origin, • obesity, • lack of exercise, • smoking, • excessive alcohol consumption, • high amount of salt in your diet, • high fat diet, and • stress. A number of other medical conditions have also been linked to an increase chance in developing essential high blood pressure, such as diabetes and kidney disease. Secondary high blood pressure A small amount of cases of high blood pressure (approximately 5%) are the result of an underlying condition or cause. These include: • kidney conditions, such as a kidney infection, or kidney disease, • narrowing of the arteries, • hormonal conditions, such as Cushing's syndrome (a condition where your body produces an excess of steroid hormones), • conditions affecting the tissue of the body, such as lupus (a condition where your immune system attacks healthy tissue), • medicines, such as the oral contraceptive pill, or the type of painkillers known as nonsteriodal anti-inflammatory drugs (NSAIDs), such as ibuprofen, • excessive alcohol consumption, and • illegal stimulants, such as cocaine, amphetamine and crystal meth”

Prognostic Significance of Between-Arm Blood Pressure Differences (Hypertension. 2008) “Every 10-mm Hg difference in systolic BP between the arms conferred a mortality hazard of 1.24 (95% CI: 1.01 to 1.52) after adjusting for average systolic BP and chronic kidney disease. BP differences between arms are reproducible and carry prognostic information. Patients should have evaluation of BP in both arms at the screening visit.”

Salt intake, blood pressure and clinical outcomes. (Current Opinion in Nephrology & Hypertension. 2008) “Summary: Average sodium consumption in the US population is excessively high, and well above recommended limits. Because most sodium derives from processed and restaurant foods, a reduction of sodium in these sources, as recently called for by the American Medical Association, is necessary to reduce exposure.”

Natural antioxidants from tomato extract reduce blood pressure in patients with grade-1 hypertension: a double-blind, placebo-controlled pilot study. (Am Heart J. 2006)"A short-term treatment with antioxidant-rich tomato extract can reduce blood pressure in patients with grade-1 HT, naive to drug therapy."