Scientists clash over health effects of salt

A WAR of words has broken out over whether salt in the diet causes high blood pressure, with a leading British expert on hypertension accusing a prestigious American scientific journal of irresponsibility.

An article in the current issue of Science suggests that hypertension may be the result of a mineral-poor diet rather than high-salt intake. A second paper also asks whether scientists should abandon the orthodox view that salt is bad for health.

But Professor Graham MacGregor, professor of cardiovascular medicine at St George's Hospital in London and a leading critic of the salt lobby, accused the journal yesterday of publishing ''bad science''. ''It is completely irresponsible. Both papers present a very misleading account of the evidence. The situation is reminiscent of the Seventies when evidence relating cigarette smoking to lung cancer and heart attacks was disputed,'' he said.

''There is now a wealth of evidence to show that a high- salt intake is a major cause of high blood pressure, which is the most important cause of strokes and a major predisposing factor to heart attacks,'' Professor MacGregor said.

A number of studies on the effects of salt have appeared over the past two years which appear to contradict each other. Critics of a high-salt diet believe the food industry, which has sponsored research into salt, is attempting to promote the idea that salt is safe.

David McCarron, a scientist at Oregon Health Sciences University in Portland, says in Science that the role of salt in hypertension has long been debated and the conclusions are not clear. "The adequate intake of minerals, rather than restriction of sodium, should be the focus of dietary recommendations," he says.

He suggests that the shift in most people's dietary patterns from nutrient- rich foods such as milk, fruits and vegetables, to nutrient-poor foods, such as chips and soft drinks, is far more likely than salt to contribute to hypertension.

Professor MacGregor emphasised that British government advisers who have reviewed all the evidence relating to dietary salt have failed to come to the same conclusions.

The Committee on Medical Aspects of Food Policy has recommended a reduction in salt intake of 30 per cent for the British population.

Professor MacGregor said this would require co-operation from the food industry, because between 70 and 80 per cent of our salt intake now comes from processed foods such as bread, cereals and meat products.

''If salt intake is reduced in the whole UK population, all the evidence suggests that this will result in a large reduction in both strokes and heart attacks - the two major causes of death and disability - as well as potential benefits in reducing cancer of the stomach and osteoporosis,'' he said.