Alcohol: How many units per week should you drink? How long it stays in your body and links to blood pressure

Just one alcoholic drink a day could raise a person’s blood pressure, a new study suggests.

Researchers say people should avoid alcohol altogether after finding that routinely drinking, even in small quantities, can increase a person’s blood pressure.

While the largest increases were seen among heavy drinkers, the international team of academics were “surprised” to find that drinking at low levels also had an effect. When a person’s blood pressure is too high it puts extra strain on blood vessels, heart and other organs, such as the brain, kidneys and eyes.

Persistent high blood pressure can lead to a number of serious health problems including heart attacks, strokes and vascular dementia.

While there are medications which can help, people can make a number of life-style changes to help bring their blood pressure down including regular exercise, losing weight, cutting back on caffeine, alcohol and salt.

The new study, published in the Hypertension – an American Heart Association journal, saw researchers examine data from seven international studies on drinking and high blood pressure.

Academics found a link between increases in systolic blood pressure – which notes the force at which the heart pumps blood around the body – and the number of daily alcoholic drinks. Even people who drank one alcoholic beverage each day showed a link to higher blood pressure when compared to non-drinkers.

They also found an increase in diastolic blood pressure – the resistance to the blood flow in the blood vessels between heartbeats when blood is pumped around the heart – in men but not in women.

Senior study author Professor Marco Vinceti from the medical school of the University of Modena and Reggio Emilia University in Italy and an adjunct professor at Boston University’s school of public health said: “We found no beneficial effects in adults who drank a low level of alcohol compared to those who did not drink alcohol.

“We were somewhat surprised to see that consuming an already-low level of alcohol was also linked to higher blood pressure changes over time compared to no consumption – although far less than the blood pressure increase seen in heavy drinkers.

“Alcohol is certainly not the sole driver of increases in blood pressure; however, our findings confirm it contributes in a meaningful way.

“Limiting alcohol intake is advised, and avoiding it is even better.”

Study co-author Paul Whelton from Tulane University’s school of public health and tropical medicine and president of the World Hypertension League, added: “We found participants with higher starting blood pressure readings, had a stronger link between alcohol intake and blood pressure changes over time.

“This suggests that people with a trend towards increased – although still not ‘high’ – blood pressure may benefit the most from low to no alcohol consumption.”

For the average adult high blood pressure is considered to be from 140/90mmHg, according to the NHS.

People who consumed 48 grams of alcohol per day saw an average increase of 4.9 mm Hg. Men consuming 48 grams of alcohol per day saw their diastolic (bottom number) blood pressure rise by an average of 3.1 mm Hg, the authors found.

The NHS also suggests that people should not consume more than 14 units of alcohol in a week - equivalent to seven cans of beer or 175ml glasses of wine.

Upon drinking, alcohol can stay in your bloodstream for up to 12 hours, and will remain on your breath for 24 hours.

Commenting on the study, Regina Giblin, senior cardiac nurse at the British Heart Foundation, said: “This large analysis shows that even a low alcohol intake is associated with an increase in blood pressure over time.

“However, this analysis can only show an association – it can’t prove cause and effect – so further research is needed.

“If you do drink alcohol, it’s important to always keep within the guidelines of up to 14 units of alcohol each week.

“Regularly drinking more than this can be harmful, leading to health problems including high blood pressure. You should also try to have several alcohol-free days each week.

“However, alcohol isn’t the only factor that can affect blood pressure and increase your risk of heart and circulatory diseases.

“Adopting a healthy lifestyle – including eating well balanced meals, exercising regularly, stopping smoking, keeping your cholesterol at a healthy level, and controlling your weight – can all help to reduce your risk of heart attacks and strokes.”