Is salt really bad for the heart? New study says no; experts say yes

A new study that suggests salt may not be as bad as we’ve been led to believe has been roundly criticised by experts who say the overwhelming evidence points to salt being bad for the heart.

The study, published in JAMA Internal Medicine, found that salt intake was not associated with mortality, risk for cardiovascular disease or heart failure in older adults. The researchers analysed the self-reported estimated sodium intake and health of 2642 adults aged 71 to 80 over a 10-year period.

However, many experts claim that the study is flawed and say we should still be aiming to reduce sodium intake.

“This study contains methodological flaws in many domains that have been repeatedly highlighted in the international literature and that make the study and the results unreliable and in danger of misleading researchers and the public,” said Professor Francesco Cappuccio, chair of Cardiovascular Medicine & Epidemiology, University of Warwick.

“Following previous recommendations, we should consider what the data show: using inaccurate measures of sodium intake and a self-selected population of older man and women, the study confirms that a higher salt intake is associated with higher mortality even in this group, and that there is no evidence of harm for levels of sodium below the current global recommendation of 5 g of salt per day (equivalent to <2000 mg of sodium).”

Professor Cappuccio says the researchers cited “questionable” evidence that was withdrawn in 2013 and says this points to the study’s “very poor scientific rigour”.

Professor Anna Dominicza, Regium Professor of Medicine, University of Glasgow, has called for “a cautious interpretation of the main conclusion” and says stronger evidence is required.

Self-reporting on diet is problematic, according to Dr Tim Chico, Reader in Cardiovascular Medicine and consultant cardiologist, University of Sheffield.

“This study highlights how difficult it is to understand the relationship between lifestyle and health, and no single study can ever give a conclusive answer,” Dr Chico said.

“People are understandably confused by the conflicting results of scientific studies on the relationship between diet and health. Instead of concentrating on individual studies (which often only get attention if their results are unusual or surprising), it is much better to look at the overall message from all these studies. These are pretty clear: a healthy diet is varied, contains a high proportion of vegetables and a low amount of processed food, and does not provide more calories than needed to maintain a healthy weight. At the end of the day, most people don’t need a doctor or a scientist to tell them that an apple is almost certainly healthier than a packet of crisps.”

The study is available here.