Researchers at the University of Utah School of Medicine say the presence of the gene could explain why some people are more sensitive to salt than others.

Writing in the American Heart Association's journal Hypertension, they say people with the gene appear to be more responsive to a low-salt diet.

Previous research had suggested the angiotensinogen gene, which comes in three variations, may play a role in lowering blood pressure.

But the new research shows the blood pressure of people with the AA version of the gene is reduced by an average 2.2mm/Hg when they are fed a low-salt diet.

The American Heart Association says a 2.2mm/Hg drop could result in a 15% reduced risk of stroke and a 6% reduction in the risk of heart disease.

Salt-sensitive

Blood pressure also drops for those with other versions of the gene, but they could not maintain the reduction over a three-year period.

Steven Hunt, one of the researchers, said: "This is a first step to defining who is salt-sensitive and who is not."

There is much controversy about the role of salt in increasing blood pressure.

Some scientists say overall diet is more important for people with a tendency to high blood pressure than simply reducing salt.

The American Heart Association recommends bananas as a source of minerals

The American Heart Association recently issued a recommendation that people with high blood pressure eat a low-fat diet and increase their mineral content as well as reducing salt intake.

The move followed extensive research into the benefits of a diet rich in minerals such as potassium, calcium and magnesium.

Bananas, potatoes and dates are high in these minerals.

The University of Utah researchers say further research is needed on the so-called salt gene.