Body weight has a major effect on blood pressure

Researchers from University College London studied over 3,600 people who were born in 1946 and followed them through middle age.

High blood pressure is usually diagnosed later in life, and people often only tackle their weight then.

But this study indicates people need to act early in life to reduce the risk of developing problems later on.

A low birthweight and growing up in a poor background also had an effect on people's risk, researchers found.

These findings highlight the importance of weight control throughout life in the prevention of raised blood pressure during middle age Rebecca Hardy, University College London

High blood pressure can lead to heart attacks, strokes, and kidney damage if it is not controlled.

Researchers measured the blood pressure of study participants aged 36, 43 and 53.

They found a strong link between high body mass index (BMI) and high blood pressure when they examined people at the age of 36.

They also found people with a high BMI showed a faster increase in blood pressure up to the age of 53 than those with lower BMIs.

A person's BMI is calculated by dividing their weight in kilograms by the square of their height in metres.

Social class link

People who grew up in a manual social class had higher blood pressure levels than those from a non-manual class.

The researchers say this difference was largely due to people from a manual social class background being heavier as adults than those from a non-manual background.

Rebecca Hardy, who led the research, said: "These findings highlight the importance of weight control throughout life in the prevention of raised blood pressure during middle age.

"Understanding the mechanisms linking the childhood socioeconomic environment and adult body-mass index may make prevention strategies more effective."

Professor Jeremy Pearson, associate medical director of the British Heart Foundation, told BBC News Online: "This reinforces the need for people to maintain a healthy weight throughout their life by cutting saturated fat from their diet and eating plenty of fruit and vegetables."

Birthweight

Those who had weighed the least when they were born - under 2,500 grammes (around six-and-a-half pounds) - had the highest risk of developing high blood pressure later in life.

There is increasing evidence that babies with low birthweight may be at higher risk of developing cardiovascular disease in later life, because they develop higher blood pressure as adults.

Professor Pearson said: "This study adds further evidence to this and strengthens the need for more research to understand how maternal nutrition during pregnancy affects foetal development."

Two blood pressure readings are normally taken - systolic, which coincides with each beat of the heart, and diastolic which measures the level between beats.

A blood pressure of 120 (systolic) over 80 (diastolic) is considered ideal for young and middle aged adults.

Blood pressure of 140/90 is seen as a cause for concern while 160/95 is definitely high and requires treatment.