New research shows for the first time that a modest reduction in salt intake causes large falls in blood pressure in isolated systolic hypertension. This would have a major effect on strokes, heart attacks and heart failure.

23rd June

A new study , published this week in the journal Hypertension, shows that a modest reduction in salt intake, from around 10g to 5g of salt per day, in patients with isolated systolic hypertension results in a large fall in average systolic blood pressure of 10 mmHg.  This reduction in blood pressure would reduce stroke by approximately one-third, coronary heart disease by one-quarter and heart failure by just over a quarter.

In people over the age of 60, isolated systolic hypertension is the predominant form of raised blood pressure and carries the highest risk of cardiovascular disease i.e. stroke, heart attack and heart failure.

Whilst many studies have shown that reducing salt intake lowers blood pressure in individuals with high blood pressure, none have looked at the effects of salt reduction on isolated systolic hypertension.  One paper, based on a dietary survey from the third and fourth National Health and Nutrition Examination Survey in the US (NHANES III and IV), has even suggested that salt reduction should not be advised in isolated systolic hypertension .   However, the methods of documenting dietary intakes in NHANES III and IV are subject to substantial bias and error and the study did not examine the effect of reducing salt intake, which this new study does.  The current study is based on an analysis of double-blind salt reduction trials to determine directly the effects of a modest reduction in salt intake on isolated systolic hypertension.

“This new study demonstrates that an easily achievable reduction in salt intake results in large falls in blood pressure in isolated systolic hypertension and reinforces the need for salt intake in the UK to be reduced below 6g per day," said Professor Neil Poulter, member of Consensus Action on Salt and Health, Professor of Preventive Cardiovascular Medicine at Imperial College London, and President of the British Hypertension Society.  “With the evidence now available to us, every healthcare professional treating people with isolated systolic hypertension should be telling them how to reduce their salt intake to 6g or less per day.”

“These reductions in blood pressure in this study are similar to those observed in clinical trials where patients have been given single drug therapy,” continues Professor Poulter.  “Cutting salt is a simple way for people to reduce their high blood pressure and in this particular group it is very beneficial either on its own or combined with tablets to control blood pressure.”

Click here for the full journal article

Notes to editors
• Consensus Action on Salt and Health (CASH) is a group of the UK’s leading experts on salt and its effects on health.  It is working to reach a consensus with the food industry and government over the harmful effects of a high salt diet, and bring about a reduction in the amount of salt in processed foods as well as salt added to cooking and at the table, so that salt intake in the UK is reduced in adults to below 6g a day, and less for children.
• Neil Poulter is Professor of Preventive Cardiovascular Medicine at Imperial College, London and President of the British Hypertension Society.

References

He FJ, Markandu ND, MacGregor GA.  Modest salt reduction lowers blood pressure in both isolated systolic hypertension and combined hypertension.  Hypertension. 2005;46:66-70

 Townsend MS, Fulgoni VL III, Stern JS, Adu-Afarwuah S, McCarron DA.  Low mineral intake is associated with high systolic blood pressure in the Third and Fourth National Health and Nutrition Examination Surveys.  Could we all be right? Am J Hypertens. 2005;18:261-269.