Franz H. Messerli
Consumption of sodium was associated with CHD and stroke risk only when it exceeded 5 g per day, according to new data from the PURE study.
Among the 18 countries in the study, only one, China, had average sodium consumption exceed 5 g per day in at least 80% of its participating communities.
“The World Health Organization recommends consumption of less than 2 g of sodium — that’s one teaspoon of salt — a day as a preventive measure against cardiovascular disease, but there is little evidence in terms of improved health outcomes that individuals ever achieve at such a low level,” Andrew Mente, PhD, principal investigator for the epidemiology program at Population Health Research Institute at McMaster University and Hamilton Health Sciences in Ontario, Canada, said in a press release. “Only in the communities with the most sodium intake — those over 5 g a day of sodium — which is mainly in China, did we find a direct link between sodium intake and major cardiovascular events like heart attack and stroke. In communities that consumed less than 5 g of sodium a day, the opposite was the case. Sodium consumption was inversely associated with myocardial infarction or heart attacks and total mortality, and no increase in stroke.”
Mente and colleagues assessed community-level associations between sodium and potassium intake and BP in 369 communities (n = 95,767) and between sodium and potassium intake and CVD and mortality in 255 communities (n = 82,544). Median follow-up was 8.1 years.
In countries other than China, 84% of communities had mean sodium intake between 3 g and 5 g per day, the researchers wrote.
Mean systolic BP rose by 2.86 mm Hg per 1-g increase in mean sodium intake, but the association was significant only in communities in the highest tertile of sodium intake (P < .0001 for heterogeneity), according to the researchers.
There were significant deviations from linearity in the associations between mean sodium intake and major CV events (P = .043) due to an inverse association in the lowest tertile of sodium intake (mean intake, 4.04 g per day; range, 3.42-4.43; change, –1 events per 1,000 years; 95% CI, –2 to –0.01), no association in the middle tertile of sodium intake (mean intake, 4.7 g per day; range, 4.44-5.05; change, 0.24 events per 1,000 years; 95% CI, –2.12 to 2.61) and a positive but nonsignificant association in the highest tertile of sodium intake (mean intake, 5.5 g per day; range, 5.08-7.49; change, 0.37 events per 1,000 years; 95% CI, –0.03 to 0.78), the researchers wrote.
In China, there was a strong association between sodium intake and stroke risk (mean sodium intake, 5.58 g per day; change, 0.42 events per 1,000 years; 95% CI, 0.16-0.67); this was significant but weaker in other countries (P for heterogeneity = .0001).
In all participating countries, increased potassium intake was associated with decreased risk for all major CV events.
“We found all major cardiovascular problems, including death, decreased in communities and countries where there is an increased consumption of potassium, which is found in foods such as fruits, vegetables, dairy foods, potatoes and nuts and beans,” Mente said in the release.
Randomized trial needed
“Before we change recommendations, let us remember that Mente and colleagues’ findings are observational data in a predominately Asian population and that base 24-hour sodium excretion was estimated from overnight fasting urine measurements. It does not necessarily follow that active intervention, such as decreasing salt intake in patients at risk of stroke or increasing salt intake in patients at risk of myocardial infarction, will turn out to be beneficial,” Cardiology Today Editorial Board Member Franz H. Messerli, MD, from Icahn School of Medicine at Mount Sinai, and colleagues wrote in a related editorial. “Nevertheless, the findings are exceedingly provocative and should be tested in a randomized controlled trial. Indeed, such a trial has been proposed in a closely controlled environment, the federal prison population in the USA.” – by Erik Swain
Disclosures: The authors report no relevant financial disclosures. Messerli reports he has received grants, advisory board honoraria and speaking honoraria from Medscape, Medtronic, Menarini, Novartis and Pfizer. Please see the editorial for the other authors’ relevant financial disclosures.