To some of the well known risk factors for strokes like smoking, high blood pressure and diabetes, researchers have now added a new risk factor - the more the number of fast-food and take-away joints in the neighbourhood, the more the risk of strokes in that area.

The findings were presented by a team of researchers led by Dr. Morgenstern of the University of Ann Arbor at the International Stroke Conference organised by the American Stroke Association in San Diego.

The research suggests that people living in neighborhoods with many fast-food and take-away joints could face increased risk of stroke by 13 per cent, compared to people staying in places with fewer such outlets.

The team conducted a study on 1,247 ischaemic stroke victims in Nueces County, Texas, from January 2000 through June 2003, where most of them were living in close proximity to 262 fast-food joints in the county and arrived at the conclusion that with every fast-food joint near a person's house, the risk of stroke increased by 1 per cent.

The researchers selected only those fast-food joints that had at least two of the four main characteristics of such outlets - fast food service, takeaway business, either with limited or no waiting staff and where payments were made prior to receiving food with the most to least number of fast-food joints being ranked.

Although the researchers were unable to come up with exact numbers, but the census took neighborhoods in the top 25 per cent that had 33 fast-food outlets per tract and approximately 5,000 people, while those in the lowest tract had 12 fast-food outlets. The study also factored socio-economic status and demographic profiles before arriving at its conclusion.

Study leader professor Lewis Morgenstern from the University of Michigan, said, "Is it direct consumption of fast-food? Is it the lack of more healthy options? Is there something completely different in these neighbourhoods associated with poor health?"

The study, which was funded by the US National Institutes of Health, had said that lab scientists and medical doctors had found that fast food is loaded with sodium, which plays an important role in blood pressure, which is one of the biggest causes of ischaemic strokes.

Fast food is known to contain high levels of salt as well as fat, the contributing factors to strokes, which occur when the brain is damaged by a loss of blood supply due to either a blockage or leak.

Joanne Murphy, the medical research liaison officer at the Stroke Association, said "We have known for some time that food high in saturated fat and salt, which is often the case with fast-food, contributes to high blood pressure and obesity, which are risk factors for stroke.

"The conclusion here is very simple, treat fast-foods as an occasional treat and only eat them as part of a balanced diet."

A single slice of Pizza served to walk-in customers, contains approximately 1,920mg of sodium while a burger has approximately 880mg, chicken club sandwich has 1,360mg while McDonald's Big Mac has 1,040mg.

Researchers said that with easy access to high-fat, high-salt food of fast-food joints, may lead to unhealthy choices of diet, which causes obesity and risk of stroke risk, however they were quick to point out that unhealthy choices made by people such as smoking, drinking excessive alcohol, and not exercising also contributed to the risk factors.

After heart disease and cancer, stroke is the number three killer in the US.