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Salt
Evidence & Action
Graham A MacGregor
Professor of Cardiovascular Medicine
Wolfson Institute of Preventive Medicine,
Barts and The London School of Medicine & Dentistry
Major Underlying Factors causing Death - Worldwide
Raised Blood Pressure
7 million
Tobacco
Developed region
High cholesterol
Developing region
Underweight
Unsafe sex
0
1
2
3
4
5
6
7
Millions of Deaths
Raised BP is responsible for
• 62% of all Strokes
• 49% of all Heart Disease
Ezzati et al. Lancet 2002:360:1347-60.
Systolic BP and Risk of Death
Stroke Deaths
Risk
Heart Deaths
32
16
16
8
8
Risk
4
4
2
2
1
120 125 135 148
168
120 125 135 148
168
Systolic Blood Pressure (mmHg)
The risk starts at systolic 115 mmHg (83% adults)
MacMahon et al. Lancet 1990;335:765-74
Atheroma in carotid artery
Plaque
Ulcerated
Plaque
Fissured Plaque
with Thrombosis
What puts up population BP?
• Salt intake
• Lack of Fruit and vegetables
• Weight
• Lack of Exercise
• (Alcohol excess)
Salt
Up to 5000 yrs ago 0.1 g/d, now 9 to 12 g/d
Why?
(a) Preserves food
(b) Cleans up bad food
Now no need
(a) Refrigeration
(b) Better chemicals
But eating 9 to 12 g/d - courtesy of the food industry
Processed
80% of salt hidden in food
Fast
Restaurant
Canteen
Salt, diet & health. 1998, Camb Uni Press
Evidence
• Epidemiology
Over 50 population studies and Intersalt
• Migration
e.g. Kenya
• Intervention
Portuguese villages. New born babies
• Genetic
All defects impair ability of the kidney to excrete Na
• Mechanisms
Plasma Na, corrected volume expansion
• Animal
BP caused or aggravated by salt (e.g. chimpanzees)
• Treatment
Meta-analysis. Dose response
• Mortality studies
Meta-analysis of cohort studies
• Outcome trials
TOHP, Taiwan (mineral salt: high K, low Na)
Randomised Double-Blind Crossover Study (N=20)
Salt Intake (g/day)
12
6
3
165
160
Systolic BP
(mmHg)
155
150
145
P<0.001 by repeated measures ANOVA.
100
Diastolic BP
(mmHg)
95
90
P<0.001 by repeated measures ANOVA.
200
Urinary Sodium
(mmol/24h)
150
100
50
0
MacGregor et al. Lancet 1989;2:1244-7.
Meta-analysis of Modest Salt Reduction Trials of one month or Longer
Hypertensive
Normotensive
0
Fall in
Systolic BP
-2
(mmHg)
-4
***
-6
***
150
Urinary
Sodium
100
(mmol/24h)
50
Usual salt intake
0
***
P<0.001 reduced salt vs. usual salt intake.
Reduced salt intake
J Hum Hypertens. 2002;16:761-770
Dose Response: Meta-analysis (1 month or longer)
4
2
0
-2
Change in
Systolic BP
(mmHg)
Normotensives
b=0.04, P<0.001
-4
-6
-8
Hypertensives
b=0.07, P<0.001
-10
-12
-30
-50
-70
-90
-110
-130
Change in Urinary Sodium (mmol/24h)
\A6
g/day reduction in salt intake predicts a fall in SBP of:
 7 mmHg in Hypertensives (p<0.001)
 4 mmHg in Normotensives (p<0.01)
 Avg. 5 mmHg
J Human Hypertens 2002;16:761
 Salt intake 5-6g/day
 Stroke 24%
 CHD 18%
He & MacGregor. Hypertension 2003;42:1093-99
UK
35,000 (approx) Stroke &
heart attack deaths
prevented / year
Worldwide 2.5 million (approx) deaths
prevented / year
Meta-analysis of cohort studies
5 g/d ↑salt intake is related to 23% ↑stroke and 17% ↑CVD
Stroke
5 g/d higher salt
CVD
5 g/d higher salt
1.6
1.4
1.2
Relative
risk
23% ↑
17% ↑
P=0.007
P=0.02
1.0
0.8
0.6
0
Strazzullo et al. BMJ 2009;339:b4567
Outcome trial
0.20
TOHP I
0.16
Control
Cumulative 0.12
Incidence
of CVD
0.08
Salt reduction
0.04
0
0.10
Cumulative
Incidence
of CVD
TOHP II
0.08
Control
0.06
Salt reduction
0.04
0.02
0
2
4
6
8
10
Follow- up (years)
12
14
16
Cook et al. BMJ 2007;334:885
 25% Salt intake (↓2.5 g/d)   25% CVD events
Japan
1960
Government campaign to reduce salt intake
Overall:
13.5 → 12.1 g/day (1.4 g/day ↓ )
Akita (North): 18 → 14 g/day (4 g/day ↓ )
BP 
80%  in stroke mortality
At this time Japan rapidly Westernised
e.g. saturated fat, smoking,  weight,  exercise
Sasaki N. The salt factor in apoplexy and hypertension: epidemiological studies in Japan. In: Yamori
Y, editor. Prophylactic Approach to Hypertensive Diseases. New York: Raven Press; 1979. p. 467-74.
Finland
Salt intake
(g/day)
Diastolic BP
(mmHg)
Stroke mortality
(1/100000)
Men
Men
Women
Women
Year
Year
Year
Karppanen & Mervaala. Prog Cardiovasc Dis 2006;49:59-75.
Reducing salt intake
• Measure salt intake
• Identify major contributors, e.g. bread,
cereals, meat products, etc
Reducing salt intake
Who is responsible?
•
Public
•
Government
•
Food industry
Developed countries 80% salt passive
\ Food industry is responsible & must take it out
How ?
•
Slowly 10-30% per year
•
No taste problems
•
Almost no technical problems
•
Voluntary but threat of legislation
•
Clear labelling
Hidden
Salt
in
food
e.g. processed, fast, takeaway, restaurant food
Food industry slowly reduce
- No rejection by public
Fantastic for Public Health
Very little
cost
↓ BP
No need to
change diet
THE UK EXAMPLE
Consensus Action on Salt & Health (CASH)
•
Members all experts on salt and BP
•
Set up 1996 in response to rejection of salt reduction recommendations
by UK Dept. of Health
Aims

•
Change Department of Health policy
•
Ensure Food Standards Agency adopted salt reduction & labeling
•
Media publicity to the public and food industry
•
Persuade retailers and food company’s to reduce salt added to food



www.actiononsalt.org.uk
CASH Strategy for Reducing Salt in UK
Salt intake
Source
g/day
Reduction
needed
Target intake
g/day
Table/Cooking (15%)
1.4 g
40% reduction
0.9 g
Natural (5%)
0.5 g
No reduction
0.5 g
Food industry (80%)
7.6 g
40% reduction
4.6 g
Total 9.5 g
Target 6.0 g
\ the food industry needs to slowly reduce salt
content of all foods by 40% over the next 5 years
Food Standards Agency (UK)
•
Set up to deal with BSE – New variant CJD
•
What else? – salt reduction
•
Gradual repeated reductions in salt added to foods by 15%-25%
•
Processed foods divided into 80 categories with targets set to be
reached by the food industry in 2010 and 2012.
•
Aim: To reduce salt intake to less than 6 g/d (adults) by 2012
Targets set in UK by FSA & CASH
•
Set targets for industry to achieve from
2005 to 2010. New targets set for 2012
over 80 categories of food
•
Gradual reduction, 10-20% a year. No
rejection by public
•
Continuous media publicity to ensure
industry collaborate
•
Praise companies achieving targets,
name and shame those not
Monitor salt intake
• Measure 24h urinary sodium in a random
sample of the population every 2 years
• Monitor reductions in the amount of salt
added to foods by the food industry & ensure
they will reach the target that has been set for
each food group
Perceived Barriers
1. Taste
2. Food technology
3. Safety
4. Commercial
Hidden Salt – Its Commercial Value
SALT
Producers (40% by value)
Profit
Food Industry
Highly Salted Processed Food
Meat
products
+ Salt
Dependence on
salty taste
(Salt Addiction)
Salt
Salt
Salt
Water
Binding
Thirst
Demand for
very salty
foods
Soft Drinks
Mineral Water
Profit
Weight
No Cost
Profit
Profit
Sea Water Comparison
(1.0 g of sodium / 2.5g of salt per 100g)
Pizza
Chicken Curry
Processed Cheese
Bacon
Sausages
Smoked Fish
Sweet Pickle
Shepherds Pie
Frozen Prawns
Crisps
Salad Cream
Savoury Biscuits
60%
60%
130%
200%
100%
190%
170%
40%
80%
110%
100%
70%
Medium Sliced White
Granary Loaf
Crumpets
Digestive
Cream Crackers
Cheddar Cheese
Stilton Cheese
Processed Cheese
Branflakes
Cornflakes
Tomato Ketchup
Brown Sauce
50%
60%
80%
60%
60%
70%
90%
130%
100%
110%
110%
100%
Above data collected 2001, n.b. most have been reduced by 10 – 30% (2008) UK only
www.salt.gov.uk
Success UK by 2008
24h urinary sodium in a random sample of
adults has fallen by 2008 (i.e. within 2 years of
starting salt reduction)
from 9.5 to 8.6 g/d salt (10% )
(i.e. 26,000 tons/yr salt removed)
≈ 6000 deaths/yr - strokes, heart attacks saved
Salt intake should reach less than 6 g/d target
around 2014
Success UK 2010
• Processed food products ↓20-40%
1. No taste problems
2. No technical problems
• Food outside home now being tackled
• Table and cooking salt sales ↓40-50%
• 24h urinary sodium in 2011
NICE Public Health Guidance
Prevention of CVD at population level
The voluntary agreement came into force
in 2004 and was followed by progressive
targets (in 2006 and 2009). The
campaigns, which cost just £15 million,
led to ≈ 6000 fewer CVD deaths per year,
saving the UK economy ≈ £1.5 billion per
annum.
http://guidance.nice.org.uk/PH25
World Action on Salt & Health
>400 members, >80 countries
Worldwide:
Individual Countries:
• Highlight foods high in
salt
• Facilitate expert groups (similar to
CASH) e.g. Canada, Australia
• Implement salt reduction
plan
• Convince government of
evidence, action by food industry
• Working with WHO
• Public health campaign to  salt
consumption at home
To join, please contact [email protected]
http://www.worldactiononsalt.com
WASH Action Groups
Actions in other countries
1.
2010, USA adopt UK model. New York, FDA, CDC
2.
2010, Australia sets salt target
3.
EU-WHO, European countries make a 16% reduction over 4 yrs.
4.
WHO/PAHO South America
Food industry could play a much more prominent role
•
Unilever & Pepsico worldwide salt reduction in their products
•
Kelloggs, Nestle about to reduce salt globally to UK levels
Summary
1. Salt intake
BP
 Stroke
 Heart Attacks
 Heart Failure
 Stomach Cancer & Osteoporosis
2.  Salt intake (cheap/practical) →
“Biggest improvement in public health
since clean water and drains (19th Century)”
He & MacGregor. Reducing population salt intake worldwide: from
evidence to implementation. Prog Cardiovasc Dis. 2010;52:363-382.