Monday, 14 April 2014

Less Salt Key Player in Drop in Stroke Deaths

It is understandable that the authors of this study want to highlight salt's role in reducing heart attack and stroke deaths. Professor Graham MacGregor, one of the three researchers, is the chairman of Consensus Action on Salt and Health (Cash), a lobby group that deserves credit for exposing the dangers of added salt in foodstuffs and part-shaming, part-persuading manufacturers to reduce it and government to oversee the process. Sonia Pombo-Rodrigues, another co-author, works for Cash.

Its role in encouraging the fall in average daily salt consumption from 9.5g a day in 2003 to 8.1g a day in 2011 is widely acknowledged, and the ensuing health benefits clearly significant. But exactly how much of the 42% drop in stroke deaths and 40% fall in ischaemic heart disease fatalities during that time is due to declining salt consumption is not agreed. The paper states that that "is likely to be an important contributor to the falls in blood pressure from 2003 to 2011 in England. [And] As a result, it would have contributed substantially to the decreases in stroke and IHD mortality". It mentions that declining rates of smoking and average cholesterol over the same years also played a part.

But these other factors are likely to be responsible for more of the falls. Indeed, the authors admit that the fall in systolic blood pressure they attribute to less salt in our diets would probably only produce 11% and 6% falls in the number of strokes and IHD respectively, a quarter and a seventh of the declines seen.

While the study does not estimate the likely impact of the falls in smoking and cholesterol, Britain's growing disenchantment with cigarettes is crucial. The British Heart Foundation lauds that as making "a huge contribution to the decline in cardiovascular disease". While 41% of women and 52% of men smoked in 1972, by 2012 just 19% of women and 22% of men did so. The public smoking bans in 2006-07 helped hugely; as, doctors hope, will plain packaging when it arrives.

There are also other reasons why UK deaths from cardiovascular disease more than halved from 335,000 in 1971 to 161,000 two years ago. Better treatments, both surgical and pharmacological, including statins, clotbusting drugs and the increasing use of primary angioplasty – the insertion of a stent to keep open a previously-blocked artery – have improved survival for those who would previously have died. It is a more complicated, but also more promising, picture than just the salt in our food we do not need but usually cannot escape.

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