Scientists have clashed over claims that sugar may be worse for blood pressure and heart health than salt.

US experts say people need to place a greater focus on cutting sugar intake and suggest the benefits of lowering salt levels are "debatable." Their arguments are published in the journal Open Heart.

But other researchers have said the claims are "disingenuous" and "scientifically unnecessary". They maintain both need to be reduced.

Focus on fructose

Researchers from St Luke's Mid America Heart Institute, and Montefiore Medical Centre in the USA reviewed a selection of evidence from basic science experiments, animal studies and human research.

They came to the conclusion that sugar - particularly fructose - may play a stronger role in high blood pressure and other cardiac conditions than salt. And they say lowering salt consumption under certain levels may do more harm than good.

The research team suggests attempts to reduce salt in processed food may drive people to eat more.

But Prof Francessco Cappuccio, at the University of Warwick, said: "The emphasis on reducing sugar and not salt is disingenuous.

"Both should be targeted at population level for an effective approach to cardiovascular prevention.

"The shift in attention from salt to sugar is scientifically unnecessary and unsupported."

Prof Tom Saunders, at King's College London, said: "Cutting salt intake and losing weight will lower blood pressure, but the evidence for a direct effect of added sugar is tenuous.

"Salt intake has fallen in the UK as manufacturers have reduced the amount of salt added to food. This has also been accompanied by a fall in blood pressure.

"Added sugar intake is derived mainly from sugar-sweetened beverages, confectionery, cereal products such as cakes and biscuits.

"The easiest way to reduce added sugar intake is to limit sugar-sweetened beverage and confectionery consumption."

Fruit and vegetables

The US experts focus on a particular type of sugar - added fructose - often found in processed foods and sugary beverages.

But they say naturally occurring sugars in whole foods, for example those in fruit and vegetables, are not a cause for concern.

Data from the National Diet and Nutrition Survey in England suggests most adults and children eat more sugar than recommended.

The World Health Organization recommends sugars should make up less than 10% of total energy intake per day - this works out at about a maximum of 50g (1.7oz) of sugar for the average adult.

But the global health body recently acknowledged that halving this, to 5% of total energy intake per day, would have additional benefits.