Reducing salt intake to reduce risk of heart attack and stroke
Submitting InstitutionSt George's, University of London
Unit of AssessmentClinical Medicine
Summary Impact TypePolitical
Research Subject Area(s)
Medical and Health Sciences: Clinical Sciences, Nutrition and Dietetics, Public Health and Health Services
Summary of the impact
MacGregor and colleagues working at St George's have provided extensive
epidemiological evidence that has changed UK government policy on
recommendations for salt
intake. In 2011 NICE recommended continued reduction in dietary salt
intake in the UK. A 3 gm
reduction in daily salt intake is calculated to result in 14-20,000 fewer
deaths from cardiovascular
disease annually, a saving of approximately £350 million in healthcare
costs, and the gain of
130,000 quality-adjusted life years. The global benefits of this policy
have been recognised with the
WHO making recommendations for similar levels of salt reduction worldwide.
MacGregor has demonstrated the relationship between salt intake and blood
pressure in an
extensive series of publications whilst working at St George's. The
clinically important question of
whether a reduction of dietary salt led to reductions in blood pressure
and hence reduced morbidity
and mortality was challenged by others in two meta-analyses of salt
reduction trials in the late
1990s. However, these meta-analyses included a large number of metabolic
studies in which salt
intake was reduced for only 4 to 5 days.
- Salt reduction reduces blood pressure
He & MacGregor demonstrated in a meta-analysis of 28 trials that a
reduction in salt intake resulted in a significant and clinically
meaningful reduction in blood
pressure [1,2]. This reduction was predicted to reduce stroke mortality
by 14% and coronary
mortality by 9% in hypertensive individuals, and by 6% and 4%
He & MacGregor went on to show a dose-response relationship between
salt intake and
blood pressure. Within the range of 12 to 3 g/d, the lower the salt
intake, the lower the
blood pressure. A salt reduction of 3 g/day predicts a fall in blood
pressure of 3.6/1.9 to
5.6/3.2 mmHg in hypertensives and 1.8/0.8 to 3.5/1.8 mmHg in
The effect would be doubled with a 6 g/d reduction and tripled with a 9
Reducing salt intake by 9 g/d (e.g. from 12 to 3 g/d) was predicted to
reduce stroke by
approximately one third and ischaemic heart disease (IHD) by one
quarter, and this would
be expected to prevent about 20,500 stroke deaths and 31,400 IHD deaths
a year in the UK
- Salt reduction in the elderly and in ethnic groups
The St George's group demonstrated that a modest reduction in salt
intake leads to a fall in
blood pressure in both normotensive and hypertensive older people of a
to that found in trials of diuretic treatment in this population, and
would therefore have an
impact on the prevention of stroke . He et al also demonstrated that
a modest reduction
in salt intake causes significant falls in blood pressure in Caucasian,
Asian, and Black
patients . Salt reduction also reduced urinary albumin excretion and
artery compliance .
- Salt reduction in children
He et al showed that in British children and adolescents, differences
in salt intake were
associated with differences in blood pressure of public health relevance
. A lower salt diet
starting from childhood may lessen the subsequent rise in blood pressure
with age and
therefore prevent the development of hypertension and cardiovascular
disease later in life.
They also demonstrated that during childhood salt is a major determinant
consumption of fluids, including sugar-sweetened soft drinks. A
reduction in salt intake
could, therefore, play a role in helping to reduce childhood obesity
through its effect on
sugar-sweetened soft drink consumption .
References to the research
1. He FJ, MacGregor GA. Effect of modest salt reduction on blood
pressure: a meta-analysis of
randomized trials. Implications for public health. J Hum Hypertens.
2. He FJ, MacGregor GA. Effect of longer-term modest salt reduction on
Cochrane Database Syst Rev. 2004:CD004937.
3. He FJ, MacGregor GA. How far should salt intake be reduced?
4. Cappuccio FP, Markandu ND, Carney C, Sagnella GA, MacGregor GA.
randomised trial of modest salt restriction in older people. Lancet.
5. He FJ, Marciniak M, Visagie E, Markandu ND, Anand V, Dalton RN,
MacGregor GA. Effect of
modest salt reduction on blood pressure, urinary albumin, and pulse wave
velocity in white, black,
and Asian mild hypertensives. Hypertension. 2009;54:482-8.
6. He FJ, Marrero NM, Macgregor GA. Salt and blood pressure in children
and adolescents. J
Hum Hypertens. 2008;22:4-11.
7. He FJ, Marrero NM, MacGregor GA. Salt intake is related to soft drink
consumption in children
and adolescents: a link to obesity? Hypertension. 2008;51:629-34.
Details of the impact
The Significance of this Research
The persuasive evidence provided by the body of work emanating from the
St George's group led
to recommendations from the Scientific Advisory Committee on Nutrition
(SACN) to reduce salt
intake. This resulted in a reduction in salt intake in the UK from a value
of 9.5 gm/day in 2003 to
8.6 gm/day in 2008 [A]. This was calculated to have reduced deaths from
by 6000 over this period at a cost of £15 million for the advertising
campaign. The calculated
saving to the UK economy was £15 billion.
The Department of Health subsequently asked NICE to provide public health
guidance on the
prevention of cardiovascular disease in the UK, and in 2011 NICE produced
its report entitled
"Guidance on the prevention of cardiovascular disease at the population
level" [B]. This wide-ranging
report considered multiple factors including dietary fats, physical
activity, food marketing
and labelling, but its primary recommendations related to salt intake and
specifically cited He and
MacGregor's work. Specifically this report recommended:
- Accelerate the reduction in salt intake among the population. Aim for
a maximum intake of
6 g per day per adult by 2015 and 3 g by 2025.
- Ensure children's salt intake does not exceed age-appropriate
guidelines (these guidelines
should be based on up-to-date assessments of the available scientific
- Promote the benefits of a reduction in the population's salt intake to
the European Union
(EU). Introduce national legislation if necessary.
- Ensure national policy on salt in England is not weakened by less
effective action in other
parts of the EU.
- Ensure food producers and caterers continue to reduce the salt content
consumed foods (including bread, meat products, cheese, soups and
This can be achieved by progressively changing recipes, products and
- Establish the principle that children under 11 should consume
substantially less salt than
adults. (This is based on advice from the Scientific Advisory Committee
- Support the Food Standards Agency so that it can continue to promote —
and take the lead
on — the development of EU-wide salt targets for processed foods.
- Establish an independent system for monitoring national salt levels in
- Ensure low-salt products are sold more cheaply than their higher salt
- Clearly label products which are naturally high in salt and cannot
reformulated. Use the Food Standards Agency-approved traffic light
system. The labels
should also state that these products should only be consumed
- Discourage the use of potassium and other substitutes to replace salt.
The aim of avoiding
potassium substitution is twofold: to help consumers' readjust their
perception of 'saltiness'
and to avoid additives which may have other effects on health.
- Promote best practice in relation to the reduction of salt
consumption, as exemplified in
these recommendations, to the wider EU.
Furthermore, the NICE clinical guidelines on management of hypertension
published in 2011
recommend dietary salt reduction in the management of hypertension.
Underpinning these recommendations was the calculation that a reduction
in mean salt intake of
3 g per day for adults (to achieve a target of 6 g daily) would lead to
around 14-20,000 fewer
deaths from CVD annually. Using conservative assumptions, this equates to
a gain of 130,000
quality-adjusted life years (QALYs), and a saving in healthcare costs
around £350 million. A
reduction of 6 g per day would lead to twice the gain: some 260,000 QALYs
and an annual saving
of £700 million.
The Reach of this Research
This work has impacted the commercial food retail world as evidenced, for
example, by statements
on Marks & Spencer, Waitrose and Tesco websites that recommend low
salt intake and have
labeled their products accordingly [C,D,E].
The global influence of this work has been extensive. In 2010 the WHO
convened a meeting on
"Strategies to monitor and evaluate population sodium consumption and
sources of sodium in the
diet" which considered a number of technical issues and strategies to
reduce salt consumption
worldwide [F]. Their report, entitled "Sodium intake for adults and
children" cites several items of
Macgregor's work [G]. The World Health Assembly passed a comprehensive
programme to reduce
non-communicable diseases, and one of the targets was for a worldwide salt
reduction of 30% by
2025 with an eventual target of 5g/day for adults. Progress towards these
aims has been achieved
in many nations, notably in Latin America.
Sources to corroborate the impact
A. Food Standards Agency. Dietary sodium levels surveys, 22 July 2008.
B. National Institute for Health and Clinical Excellence (NICE). Guidance
on the prevention of
cardiovascular disease at the population level. http://guidance.nice.org.uk/PH25.
G. WHO. Guideline: Sodium intake for adults and children. Geneva,
Organization (WHO), 2012.