Studies reveal need for larger trials on benefits of salt reduction

July 6, 2011

According to Reuters, a systematic review published by The Cochrane Library shows that while cutting salt consumption did appear to lead to slight reductions in blood pressure, it was not translated into lower death or heart disease risk.

“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 Exeter University, who led the review.

The researchers 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.

While previous trials have found there is a blood pressure benefit from cutting salt, research has yet to show if that translates into better overall heart health in the wider population. Taylor believes his review did not find any evidence of big benefits because the numbers of people studied and the salt intake reductions were relatively small.

Meanwhile, a recent study published in the Journal of the American Medical Association (JAMA) proposes that even modest reductions in salt intake may be associated with an increased risk of cardiovascular disease and death. The researchers report that people with the lowest levels of sodium in their urine (a marker of salt intake) at the start of the study had a 56% higher risk of dying from cardiovascular disease than people with the highest levels. This certainly contradicts the advice of a majority of health and federal bodies, who have been telling consumers to drastically cut back on their sodium consumption. In a recent ePerspective post, John Ruff, retired Senior Vice President of Global Quality, Scientific Affairs and Nutrition at Kraft, identifies some key flaws in the JAMA study, which impact the researchers’ findings. According to Ruff, although the study quotes a sample size of 3,681, the conclusions about cardiovascular disease (CVD) are based solely on the 84 who died during the study. Another weakness is that sodium intake was only determined for a single day over the course of the study and no calorie or other nutritional data was collected. What are your thoughts on the JAMA study? Share your opinions today at IFT’s ePerspective blog.

Reuters article

Cochrane abstract

JAMA abstract