Eating more fruit and vegetables helped a group of volunteers to make a big reduction in blood pressure, University of Oxford doctors reported in a study published on Monday.
Nearly 700 human guinea pigs took part in the project, in which they were either assigned to a group that was asked to eat more fruit and vegetables or stick to their usual diet.
Those in the first group were advised to eat at least five 80-gram servings of vegetables or fruit per day. By the end of the six months, their consumption had gone up from 3,4 servings per day to 4,8. Their systolic blood pressure decreased by 4mm of mercury (Hg) and the diastolic blood pressure fell by 1,5mm Hg.
Blood pressure is commonly measured by wrapping an inflatable cuff around the upper arm. Air is pumped into the cuff until circulation is cut off; when a stethoscope is placed over the cuff , there is silence. Then as the air is slowly let out of the cuff, blood begins to flow again and can be heard through the stethoscope.
This is the point of greatest pressure (called Systolic), and is usually expressed as how high it forces a column of mercury to rise in a tube.
At its highest normal pressure, the heart would send a column of mercury to a height of about 120 millimetres. At some point, as more and more air is let out of the cuff, the pressure exerted by the cuff is so little that the sound of the blood pulsing against the artery walls subsides and there is silence again.
This is the point of lowest pressure (called Diastolic), which normally raises the mercury to about 80 millimetres.
After the test the volunteers also had higher concentrations in their blood of five key ”antioxidant” vitamins, which help to fight against ageing and cancer.
In the control group, consumption rose by only a tiny amount, from 3,4 servings per day to 3,5. There was a small reduction in diastolic pressure, but no change at all in systolic.
Blood pressure is a major factor in the risk of heart attack.
”A reduction of 2mm Hg in diastolic blood pressure results in a population-wide decrease of about 17% in the incidence of high blood pressure, six percent in the risk of coronary heart disease and 15% in the risk of stroke and transient ischaemic attack,” said lead researcher Andrew Neil.
A transient ischaemic attack is a brief brain attack lasting from seconds to hours and is caused by a temporary interruption to the blood flow to the brain.
The study is published online by the British journal The Lancet. – Sapa-AFP