A low-salt diet could raise heart disease risk, study suggests
Appearing in The Lancet, the research asks questions of the link between increasing salt intake and raised blood pressure. This is seen more clearly in those individuals with hypertension compared with those, who do not have this condition.
Within Europe, high blood pressure is particularly an issue as it has been shown to have an increased prevalence of 60% when compared with the U.S. and Canada.
In addition, it directly causes approximately 25% of heart attacks in Europe. In its progressed form of cardiovascular disease, it is estimated to cause 42% of all deaths across the European Region annually.
Study criteria
In the study, 133 118 individuals (63 559 with hypertension and 69 559 without hypertension) with an average age of 55 years were enrolled from 49 countries.
The team, from McMaster University and Hamilton Health Sciences, looked into the link between sodium (salt) intake and death, heart disease and stroke and whether it differed in people with high blood pressure compared to those with normal blood pressure.
They showed that compared with moderate sodium intake, low sodium intake was linked to an increased risk of cardiovascular events and death in those with or without hypertension.
High sodium intake was associated with an increased risk of cardiovascular events and death in hypertensive populations.
"Our findings are important because they show that lowering sodium is best targeted at those with hypertension who also consume high sodium diets," said Andrew Mente, lead author of the study, and an associate professor of clinical epidemiology and biostatistics at McMaster University.
"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.”
The results echo those of another study, which reported an association between increased sodium intake and cardiovascular disease that was limited to participants with hypertension.
The results are also in keeping with the popular U-shaped association between sodium intake and cardiovascular disease events, in both healthy and high-risk populations.
Industry response
The Consensus Action on Salt and Health (CASH) highlighted a couple of issues with the analysis arguing that dying individuals eat little or no food.
As a result their salt intake is low. “It is not the low salt intake that is causing their death, but rather their illness that is causing their low salt intake,” the group said.
“The evidence for salt causing high blood pressure and that reducing salt intake lowers blood pressure and prevents strokes and heart attacks, is overwhelming and does not in any way overturn public health messages both in the UK and worldwide.”
There are clear examples where EU Member States have implemented interventions, and have been successful in improving public health and reducing blood pressure.
In the UK, the Public Health Responsibility Deal was launched in 2011 outlining target salt levels for 80 specific food groups.
In addition, a voluntary ‘traffic light scheme’ for labelling was introduced by the Food Standards Agency where packaged food is labelled based on fat, sugar, and salt content. Though voluntary, more than 75% of packaged foods feature the label.
The UK salt reduction initiatives have successfully seen a reduction in salt consumption from 9.5g/day in 2001 to 8.6g/day in 2008; and caused consumer awareness of daily salt intake recommendations to increase ten-fold.
Source: The Lancet
Published online ahead of print, doi:10.1016/S0140-6736(16)30467-6
“Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies.”
Authors: Andrew Mente et al.
