LONDON In an analysis likely to fuel a long-running debate over the health impacts of too much salt, researchers have found no evidence that moderate cuts to salt intake reduce the risk of developing heart disease or dying prematurely.
In a systematic review published by The Cochrane Library, British scientists found that while cutting salt consumption did appear to lead to slight reductions in blood pressure, that was not translated into lower death or heart disease risk.
The researchers said they suspected that trials conducted so far were not big enough to show any benefits to heart health, and called for large-scale studies to be carried out soon.
"With governments setting ever lower targets for salt intake and food manufacturers working to remove it from their products, it's really important that we do some large research trials to get a full understanding of the benefits and risks of reducing salt intake," said Rod Taylor of the Peninsula College of Medicine and Dentistry at Exeter University, who led the review.
Most experts are agreed that consuming too much salt is not good for you and that cutting salt intake can reduce hypertension in people with normal and high blood pressure.
But while previous trials have suggested there is a blood pressure benefit from lower salt intake, research has yet to show whether that translates into better overall heart health in the wider population.
High blood pressure, or hypertension, is a major risk factor for cardiovascular diseases such as heart failure, heart attacks and stroke, which are the world's number one killers.
Taylor said he thought it did not find any evidence of big benefits because the numbers of people studied and the salt intake reductions were relatively small.
"The people in the trials we analyzed only reduced their salt intake by a moderate amount, so the effect on blood pressure and heart disease was not large," he said.
Many developed nations have government-sanctioned guidelines calling on people to cut their salt or sodium intake for the sake of their longer-term health. The World Health Organization (WHO) lists reducing salt intake among its top 10 "best buys" for reducing rates of chronic disease.
In Britain, the National Institute of Health and Clinical Guidance (NICE) has called for an acceleration of the reduction in salt in the general population from a maximum intake of 6 grams(g) a day for adults by 2015 to 3g by 2025.
U.S. guidelines recommend Americans consume less than 2.3g of salt daily, or 1.5g for certain people who are more at risk for high blood pressure or heart disease.
An earlier Cochrane review of dietary advice published in 2004 could not find enough evidence to draw any conclusions about the effects of reducing salt intake on death rates or on rates of heart disease.
In this latest review, Taylor's team found seven studies that together included 6,489 participants. This gave the researchers enough data to be able to start drawing conclusions, they said, but even so, the scientists think they would need to have data from at least 18,000 people before they could expect to identify any clear health benefits.
A leading WHO nutrition adviser told Reuters in an interview last year that governments around the world could save huge health costs and avert millions of early deaths if they introduced laws to cut salt levels in food.
(Editing by Alison Williams)
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