Blood pressure refers to the pressure that blood exerts on the blood vessels as it travels through circulation. It's most commonly measured with an auscultatory approach, using a sphygmomanometer, a stethoscope, and a cuff to measure pressure at two points: systolic, which is the maximum pressure during a contraction, and diastolic, which is the minimum pressure between contractions. BP is normally measured in millimeters of mercury (a unit of pressure) above the atmospheric pressure.
Blood pressure is either measured in a single sitting or as ambulatory pressure, over 24 hours with a leave-on cuff. The latter is likely to be more accurate and aboid anomalous measurements, since blood pressure can naturally fluctuate throughout the day.
Food and supplements that affect blood pressure may do so through improving the ability of blood vessels to dilate due to nitric oxide signaling, inhibiting angiotensin, which causes vasoconstriction, modifying blood volume, protecting blood vessels, or by playing a role in the function of endothelial cells.
High blood pressure (hypertension) is a risk factor for atherosclerosis, while low blood pressure (hypotension) can be a result of a variety of illnesses and may lead to weakness and dizziness due to inadequate blood flow.