Salt lovers salivate on any contrarian health news defending the modern Western diet high in sodium, like global warming denialists hoping for the best.
Like the scientific discussion over global climate change, consensus on the dangers of dietary salt remains fleeting as some studies contradict health advice from the Centers for Disease Control and Prevention, among others. A 2011 meta-analysis of seven studies covering more than 6,200 patients found “no strong evidence” that cutting salt reduces the risk for heart attack, stroke, or early death among those suffering from hypertension. Just prior to that study in the American Journal of Hypertension, European researchers reported that a reduced salt intake — as measured through urinalysis — was associated with an even greater risk of dying for those with high blood pressure.
Yet new evidence from the United Kingdom following a widespread effort begun in 2003 to reduce dietary salt consumption shows a dramatic 40 percent drop in deaths from heart disease and stroke during that time. Researchers at the Institute of Preventive Medicine in London analyzed data from more than 31,500 people participating in a national health survey conducted in 2003, 2006, 2008, and 2011.
Though people in the study reduced their salt intake by 15 percent overall, Graham MacGregor and his fellow researchers said consumption of salt remains too high. Regardless of the leap from dietary salt to the development of heart disease and stroke, scientists say the evidence is clear that high-salt diets raise blood pressure, which is a risk factor for those diseases.
During the survey period, deaths from stroke fell by 42 percent in the UK, while deaths from coronary heart disease plummeted by 40 percent. Those mortality drops matched an attendant drop in the prevalence of risk factors such as average cholesterol, hypertension, and smoking — with the exception of rising body weights throughout the study population. Yet the consumption of fruits and vegetables also rose, slightly.
Specifically, the researchers found that average daily salt consumption fell by 1.4 grams during the study period for an overall drop of 15 percent. Whereas they measured salt consumption among those in the study taking blood pressure medication, results for others were based on population-wide trends in lowered salt intake. The researches were also unable to track individuals in the study or to isolate the effects of lowered salt consumption from factors such as exercise.
"The reduction in salt intake is likely to be an important contributor to the falls in blood pressure in England from 2003 to 2011,” Graham wrote in the study. “As a result, the decrease in salt intake would have played an important role in the reduction in stroke and ischaemic heart disease mortality during this period."
The new research follows a similar conclusion supporting the link between high dietary salt and heightened risk for dying of heart disease and stroke, which was published in the British Medical Journal.
As much as 70 percent of the British population is still consuming more than the daily recommended amount of salt — with 80 percent of that salt coming from processed foods.
Source: Graudal N, Jurgens G, Baslund B, Alderman MH. Compared With Ususal Sodium Intake, Low- And Excessive- Sodium Diets Are Associated With Increased Mortality: A Meta-Analysis. Journal of Hypertension. 2011.