Most of us don't need to worry about consuming too much salt and official guidelines for consumption are set too low, according to the Irish author of a study published in the Lancet.
The study, which challenges official dietary advice on salt intake, suggests most people are consuming the right amount of salt. In contrast, it warns against the dangers of low-salt diets and says they may increase the risk of heart disease and death.
The research questions the appropriateness of current guidelines that recommend low salt intake in the entire population, according to co-author Prof Martin O’Donnell of NUI Galway.
“Until definitive trials are completed, an approach that recommends salt in moderation, particularly focused on those with hypertension [high blood pressure], appears more in line with current evidence,” he said.
Low salt intake is defined in the study as fewer than 7.6 grams per day (3g of sodium). Irish people currently consume about 9g of salt but current dietary guidelines aim to reduce this to below 6g.
Prof O’Donnell said the study challenges established dogma that “the lower the salt intake the better” but he admitted the findings have generated “blowback” among cardiologists and other medical groups.
“Our findings highlight the need for a definitive clinical trial that determines the safety and effectiveness of sustained low sodium intake on incidence of heart attacks and stroke.”
Researchers looked at whether the relationship between salt intake and death, heart disease and stroke was different in people with high blood pressure compared to those with normal blood pressure.
The results, compiled from observations of more than 130,000 people from 49 countries, showed that, regardless of whether people had high blood pressure, low salt intake was related to more heart attacks, strokes and deaths.
“These are extremely important findings for those who are suffering from high blood pressure.
“While our data highlights the importance of reducing high salt intake in people with hypertension, it does not support reducing salt intake to low levels,” said lead author Dr Andrew Mente of McMaster’s University in Canada.
“Our findings are important because they show that lowering sodium is best targeted at those with hypertension who also consume high-sodium diets.”
The findings show that while there is a limit below which salt intake may be unsafe, the harm associated with high salt consumption appears to be confined to those with high blood pressure. Only about 10 per cent of the population in the study had both high blood pressure and high salt consumption (greater than 15g per day).
Dr Mente said that this showed the majority of individuals are consuming the right amount of salt and suggests that targeted salt reduction in those who are most susceptible – those with high blood pressure and high salt consumption – may be preferable to a population-wide approach.
He added that what is now generally recommended as a healthy daily ceiling for sodium consumption appears to be set too low, regardless of a person’s blood pressure level.