Drinking alcohol, even moderate amounts, may boost blood pressure more than previously thought, researchers said.

People with a genetic mutation that makes it difficult to consume alcohol had significantly lower blood pressure than regular or heavy drinkers, the researchers found.

People without the mutation who had about three drinks per day had "strikingly" higher blood pressure than people with the genetic change who tended to drink only small amounts or nothing at all.

"This study shows that alcohol intake may increase blood pressure to a much greater extent, even among moderate drinkers, than previously thought," Sarah Lewis, a researcher at the University of Bristol's Department of Social Medicine, and colleagues wrote in their report published in the Public Library of Science journal PLoS Medicine. The researchers said there was more than a two-fold risk for high blood pressure among drinkers and a 70 per cent increased risk for "quite modest" drinkers compared to people with the genetic mutation.

High blood pressure, which affects more than a billion adults worldwide, can lead to stroke, heart failure, heart attack and kidney failure.

Previous studies have linked heavy drinking with high blood pressure while others have suggested that moderate alcohol intake provides health benefits such as lower cholesterol. The genetic mutation is common in some Asian populations and discourages drinking because alcohol triggers facial flushing, nausea, drowsiness, headache and other unpleasant symptoms.

Comparing people with the mutation and volunteers without the genetic variation helped the researchers better gauge long-term effects of drinking, they said.