Dietary salt reduction associated with health benefits in U.K.
by Keith Nunes
In 2003, the United Kingdom’s Scientific Advisory Committee on Nutrition published a report on salt and health, and concluded a population-wide effort to reduce dietary salt intake would lead to public health benefits. The recommendation led to the development of voluntary sodium reduction guidelines for the food industry, and, at the same time, efforts were made to educate British consumers about the possible negative health effects of consuming too much sodium. Now a study published this past April in a publication associated with the British Medical Journal indicated the efforts may have had a positive effect.
The study, titled “Salt reduction in England from 2003 to 2011: Its relationship to blood pressure, stroke and ischaemic heart disease mortality,” was published in the on-line journal BMJ Open and concluded that a relationship between sodium reduction efforts between 2003 to 2011 led to a 15% reduction in average sodium intake and stroke deaths fell by approximately 40%.
“The British government has successfully educated individuals about reducing their sodium consumption and has aggressively encouraged companies to market less-salty foods,” said Michael Jacobson, executive director of the Center for Science in the Public Interest, Washington. “And according to the findings published in BMJ Open, those efforts are likely partly responsible for plummeting rates of heart attack and stroke deaths in the United Kingdom.”
The study’s authors based their findings on an analysis of data from more than 31,500 people taking part in the Health Survey for England for the years 2003 — when efforts to curb population wide salt intake began across the U.K. — 2006, 2008, and 2011. The survey involved a random representative sample of the adult population of England living in private households, and included information on diet and blood pressure measurements.
The average population salt intake was calculated from urine collected over a 24-hour period in almost 3,000 people who were part of the National Diet and Nutrition Survey between 2003 and 2011. The survey involved random samples of the population.
During the period, nationally collated figures showed that stroke deaths fell by 42% while deaths from coronary heart disease dropped by 40% in England, according to the study. In addition, the prevalence of several risk factors for cardiovascular disease also declined, including average cholesterol, blood pressure and smoking, although average weight rose. The study’s authors also noted fruit and vegetable consumption rose slightly.
With the exception of increasing weight gain, all the trends, along with better treatment of cardiovascular disease and its risk factors would have probably contributed to the dramatic falls in stroke and heart disease deaths, according to the study. But daily salt intake fell by an average of 1.4 grams during the period, amounting to a drop of 15%.
Among the survey participants not taking blood pressure lowering drugs, average blood pressure still fell, even after taking into account other influential factors, the study said. The study’s authors concluded the fall in salt consumption in the population samples suggested that the decrease in blood pressure largely would have been attributable to less dietary salt rather than to medication.
But they cautioned that they used several sets of data, involving different people, so were not able to track changes at the individual level, nor were they able to account for physical activity levels.
Nevertheless, the authors concluded: “The reduction in salt intake is likely to be an important contributor to the falls in blood pressure in England from 2003 to 2011. 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.”
And they go on to say that despite considerable progress, 70% of the adult population is still eating more than the recommended 6 grams per day, with 80% of intake coming from processed foods.
“Therefore, continuing and much greater efforts are needed to achieve further reductions in salt intake to prevent the maximum number of stroke and heart disease deaths,” they said.
Critics of the study noted that there is no evidence that shows a relationship between the fall in dietary salt consumption and the reduction in cardiovascular disease.
The authors noted the limitations of the study.
“Because we used data from national surveys that included different sets of participants both cross-sectionally and longitudinally, we were unable to work with data at the individual level, particularly as salt intake was not measured in the same participants who had B.P. and other C.V.D. risk factors recorded,” they said. “Therefore, the results of our study could possibly be subject to ecological bias.”
The limitations of the study, however, did not stop some groups from highlighting its results.
“This study illustrates just how profoundly people’s health can improve when sodium intake is reduced in the food supply,” said Nancy Brown, chief executive officer of the American Heart Association, Dallas. “And this is very promising news as the American Heart Association and other public-health advocates continue to work with food industry and government leaders in the United States.
“Many in the food industry have voiced concern that reduced-sodium products would not taste the same, but the efforts of industry and health organizations in the United Kingdom have shown exactly the opposite. In fact, salt has been reduced 20% to 40% in processed foods without a loss of sales. More importantly, high blood pressure, heart attacks and strokes all dropped, according to the U.K. study.
“The American Heart Association believes many lives can be saved through bold innovations such as the development of new food technologies and implementation of federal sodium reduction standards for packaged and restaurant foods. These products combine to make up about 75% of the sodium intake for the average American.”