Light alcohol consumption may reduce a person's risk of the most common type of stroke but heavy drinking significantly increases the risk, new research shows.

Up to two alcoholic drinks per day may reduce the risk of the most common type of stroke by almost a tenth, a new study has found.

But that's where any potential benefit from alcohol consumption and stroke risk stops.

Research published in the journal BMC Medicine shows light to moderate alcohol consumption is associated with a lower risk of ischemic stroke.

There was, however, no effect on a person's risk of haemorrhagic stroke - the most deadly type.

In contrast, high-to-heavy drinking was associated with an increased risk of all stroke types, according to the meta-analysis of more than 25 cohort studies involving about 20,000 Swedish stroke patients.

"Our results showed heavy drinkers were about 1.6 times more likely to suffer from intracerebral haemorrhage and 1.8 times more likely to suffer from subarachnoid haemorrhage," said lead author Dr Sussanna Larsson.

People who consumed up to one drink a day were 10 per cent less likely to suffer a ischemic stroke.

This benefit reduced to eight per cent if a person had one or two drinks.

Previous research has found an association between alcohol consumption and lower levels of fibrinogen - a protein in the body which helps the formation of blood clots.

While this may explain the association between light to moderate alcohol consumption and lower ischemic stroke risk, the adverse effect of alcohol consumption on blood pressure - a major risk factor for stroke - may increase the risk of haemorrhagic stroke and outweigh any potential benefit," said Dr Larsson.

Ischemic stroke is caused by blood clots which block diseased or damaged cerebral arteries.

Haemorrhagic stroke occurs when a weakened blood vessel, such as an aneurism, bursts and bleeds either within the brain.

The researchers at Karolinska Institutet in Sweden and University of Cambridge, UK, acknowledge that because it was only an observational study their findings only show a possible association not cause and effect.

Associate Professor Bruce Campbell from the Australian Stroke Foundation says the study is "interesting" but more work needs to be done in this area.

He says people must be sensible and put their health first by adhering to the Australian Alcohol Guidelines' recommendation of no more than two standard alcoholic drinks per day.

"We know that excessive alcohol consumption is clearly associated with an increased risk of stroke.

"Alcohol consumption can lead to high blood pressure and irregular heart rhythm (atrial fibrillation) which are major causes of stroke," Prof Campbell said.