One alcoholic drink a day could be enough to increase the risk of heart disease, according to research contradicting claims that low to moderate consumption has a protective effect.

Previous studies have suggested that drinking 12 to 25 units a week could be good for the heart but research published in the BMJ on Friday, using data from more than 260,000 participants in 56 studies, found that even light drinkers can reduce their risk of coronary heart disease and blood pressure by cutting down.

Juan Casas, professor of epidemiology at the London School of Hygiene and Tropical Medicine, which led the study, along with UCL andPennsylvania University, said the message was clear that the less you drink the better.

“The best thing to do is to reduce consumption to reduce blood pressure and risk of heart disease,” said the study’s senior author. “We expect that these findings will help to simplify policymaking about alcoholconsumption. There was this issue about whether consumption of low to moderate consumption was good for your heart. This study shows that this is simply not the case.”

The study found that individuals who carry a genetic variant of the alcohol dehydrogenase 1B gene, which tends to lower their alcohol consumption because it causes them unpleasant symptoms, had on average a 10% lower risk of coronary heart disease. They also had lower blood pressure and a lower body mass index.

Casas said previous studies did not take account of the effect of other behaviour patterns associated with low-to-moderate alcohol consumption.

“People who drink low to moderate amounts are more likely to be engaging in physical activity and they’re more conscious about quality of diet,” he said. “That may appear to make them appear at lower risk of coronary heart disease.”

Further, he said that people who do not consume alcohol due to illness have been included in the teetotal category, making them appear to be at higher risk of heart attack from not drinking, even though other factors could be at work.

“Given that this is the first time we show findings that challenge the status quo, we are conscious that we will need replication in similar size or even bigger studies, given the importance to public health of this finding,” Casas said.

Dr Shannon Amoils, senior research adviser at the British Heart Foundation, which funded the study alongside the Medical Research Council, said: “Studies into alcohol consumption are fraught with difficulty in part because they rely on people giving accurate accounts of their drinking habits. Here, the researchers used a clever study design to get round this problem by including people who had a gene that predisposes them to drink less.”

Tim Spector, professor of genetic epidemiology at King’s College London, said the study was impressive and “rightly concludes we should not accept the dogma that alcohol drinking is good for us”. But he added: “This study has limitations because people with genes for alcohol intolerance may also have other unmeasured behaviours or traits that reduce heart disease. A good example might be if they also had different gut microbes which prevented heart disease.”

The chief medical officer, Sally Davies, has been engaged in a review of the guidelines on how much alcohol is safe to drink since 2012. The existing recommendations advise women to drink no more than two to three units of alcohol a day and men no more than three to four.