Salt intake, blood pressure and
cardiovascular disease
Francesco P Cappuccio MBBS MD MSc FRCP FFPH FAHA
Cephalon Chair of Cardiovascular Medicine & Epidemiology
Cardiovascular Medicine & Epidemiology Research Group
Clinical Sciences Research Institute
Warwick Medical School
Coventry, UK
17
Stroke and Ischemic Heart Disease (IHD)
Mortality Rate in Each Decade of Age, Versus
Usual Systolic BP at the Start of that Decade
IHD
Stroke
Age at risk
256
80–89 y
128
70–79 y
Mortality*
64
256
80–89 y
128
70–79 y
64
60–69 y
32
50–59 y
16
40–49 y
60–69 y
32
50–59 y
16
8
8
4
4
2
2
1
1
0
120
140
160
180
Usual SBP (mmHg)
Age at risk
0 120
140
160
180
Usual SBP (mmHg)
Lewington et al. Lancet 2002;360:1903–13
“More than a quarter of the world’s
adult population – totalling nearly one
billion (640 million in developing
countries) – had hypertension in 2,000,
and … this proportion will increase to
29% - 1.56 billion – by 2,025.”
Kearney PM et al. Lancet 2005;365:217-23
The prevalence of hypertension
is declining but the incidence of
hypertension is increasing
“Residual lifetime risk of developing hypertension
(lifetime cumulative incidence) is 90%”.
“Although the risk of substantially elevated blood
pressure is declining, there is still a high risk of
developing hypertension”.
Vasan R et al. JAMA 2002;287:1003-10
Salt, blood pressure and CVD
• Animal studies
• Ecological studies
• Observational studies
– Cross-sectional
– Prospective
• Intervention studies
– RCTs
– Community trials
Associations between salt intake
and CVD risk
INTERSALT. Br Med J 1988; 297: 319-28
Perry IJ & Beevers DG J Hum Hypert 1992; 6: 23-5
Schmieder RE et al Circulation 1988;78: 951-6
Dietary Sodium Reduction and Blood Pressure
17 trials in hypertensives (n=734)
11 trials in normotensives (n=2,220)
>4 wks duration
Reduction in sodium ~80 mmol/day
(~4.6 g salt per day)
-5.0 mmHg
Pooled effects:
Systolic
-4.96 mmHg (-5.75 to -4.17)
Diastolic
-2.73 mmHg (-3.21 to -2.25)
-2.0 mmHg
He FJ & MacGregor GA. J Hum Hypert 2002;16:761-70
Dose-response relationship between
sodium intake and blood pressure
He FJ & MacGregor GA. Hypertension 2003;42:1093-9
N=1,520
Median f-up 7.93 yrs
669 new cases of HPT
RR 1.26 (1.01-1.57)
RR 2.43 (1.72-3.22) for
High BP-High Na vs Low BP-Low Na
Chien K-l et al. J Hypertens 2008;26:1750-6
Predicted reductions in deaths from stroke and
IHD with reductions in salt intake in Europe
Reduction in daily salt (sodium) intake
3 g/d
(50 mmol/d)
6 g/d
(100 mmol/d)
9 g/d
(150 mmol/d)
SBP
DBP
SBP
DBP
SBP
DBP
Average fall in BP (mmHg)
2.5
1.4
5.0
2.8
7.5
4.2
Reduction in stroke death (%)
12
14
23
25
32
36
Stroke deaths prevented in
Europe per year
39,698
46,314
76,088
82,704
105,861
119,094
Reduction in IHD death (%)
9
10
16
19
23
27
116,509
136,771
IHD deaths prevented in Europe
per year
45,590
50,656
81,050
96,247
Modified from He FJ & MacGregor GA. Hypertension 2003;42:1093-9
Long-term effects of dietary sodium
reduction on CVD outcomes
TOHP I and II combined
RR: 0.70 (0.53-0.94) p=0.018
RR: 0.48 (0.25-0.92) p=0.027
 UNa 44 mmol/day reduction over 18 mo
N=744
RR: 0.79 (0.57-1.09) p=0.16
 UNa 33 mmol/day reduction over 36-48 mo
N=2,382
Cook NR et al. Br Med J 2007;334:885-8
Success stories : Finland
Mortality
2.5
Hazard ratios*
2.0
1.5
1.0
0.5
CHD
CVD
All
for a 100 mmol/d (~6g salt per day) change in sodium,
adjusted for age, year, smoking, cholesterol, HDL-C, SBP, BMI
Tuomilehto J et al. Lancet 2001; 357: 848-51
Effectiveness and costs
• Highly cost-effective in every setting
– Population decrease in salt consumption
will increase life expectancy and save
costs.
• Legislated or voluntary
• Most data regional but could easily be
contextualized
• Robust to sensitivity analyses
Selmer R, et al. JECH 2000; 54 :697-702.
Murray C et al. Lancet 2003; 361: 717-25.
Dietary salt and the cycle of profit
SALT
Profit
Producers (40% by value)
Food industry
Salt addiction
Highly salted processed food
(often > seawater)
80% of intake
High Salt
Profit
High Salt
Mineral water
Soft drinks
OBESITY
Profit
Water
binding
High Salt
Thirst
Demand for
salty foods
Meat
products
Weight
no cost
Profit
In England and Wales … levels of salt intake are
still far from the government’s recommended 6 g
of salt per day. Future options are to do nothing,
to establish voluntary target levels of salt for a
wide range of foods, or to legislate so that the
food industry has to comply. Given the inertia of
the past 20 years, the first option would not
contribute to progress. The “voluntary” option
would support existing work, but it is unlikely to
achieve the set targets. … The “legislation” option
would require the food industry to reduce the salt
content of processed food to within set levels. The
experience in Finland suggests that legislation has
added value to the previous option and at this
stage is necessary and justified.
e.g. creating
incentives
rather than
disincentives
Cappuccio FP. BMJ 2007;334:859-60
W.H.O. recent positions
To reduce the average salt consumption
of the adult population to <5g/day
2007
2008
Policies for salt iodization and reduction
of salt intake are compatible, costeffective and of public health benefit
Reliance on salt as a vehicle for the
delivery of iodine should not justify
promotion of salt intake to the public
Additional vehicles to salt for
micronutrient fortification should be
explored
Be
lg
iu
m
Ic
2
ela
nd
U
De K 1
nm
ar
k
UK
Be
2
Ne l giu
th m
er 1
l
Fi and
nl
an s
d
Ru 2
G s
er si a
m
an
y2
UK
3
Ita
ly
4
G Ma
er l t
m a
an
y1
Ita
ly
2
I
G tal
er y 3
m
a
Fi ny 3
nl
an
Sp d 1
ai
n
Sp 1
ai
n
2
Ita
Po l y 1
rtu
Po ga
la l
n
Hu d 2
ng
Po ary
la
nd
1
Task ahead!
Salt consumption in Europe in 1985-1987
Grams per day
16
14
12
10
8
6
4
2
0
Intersalt, BMJ 1988
European Salt Action Network
Conclusions
• Strong ‘causal’ evidence of the link between
excessive salt consumption and cardiovascular
disease
• High ‘attributable risk reduction’
• Population-wide salt reduction highly cost-effective
• Urgency to implement strategies, policies and
programmes to reduce dietary salt intake
• Alternative vehicles to salt for micronutrient
fortification
• Interaction with food manufacturers (local,
national, multinational)
• Voluntary vs legislative