Salt

Evidence & Action

Graham A MacGregorProfessor of Cardiovascular Medicine

Wolfson Institute of Preventive Medicine,

Barts and The London School of Medicine & Dentistry

Major Underlying Factors causing Death - Worldwide

Ezzati et al. Lancet 2002:360:1347-60.

Underweight

Unsafe sex

High cholesterol

Tobacco

Raised Blood Pressure

0 1 2 3 4 5 6 7

Millions of Deaths

7 million

Developing region

Developed region

Raised BP is responsible for

• 62% of all Strokes• 49% of all Heart Disease

Systolic BP and Risk of Death

Systolic Blood Pressure (mmHg)

Heart Deaths16

8

4

2

1

120 125 135 148 168

Risk

120 125 135 148 168

2

4

8

16

32

Stroke Deaths

The risk starts at systolic 115 mmHg (83% adults)

Risk

MacMahon et al. Lancet 1990;335:765-74

Atheroma in carotid artery

Plaque

Ulcerated Plaque

Fissured Plaquewith Thrombosis

What puts up population BP?

• Salt intake

• Lack of Fruit and vegetables

• Weight

• Lack of Exercise

• (Alcohol excess)

Up to 5000 yrs ago 0.1 g/d, now 9 to 12 g/d

Salt

Why?

Preserves food

Cleans up bad food

(a) Refrigeration

(b) Better chemicals

Now no need

But eating 9 to 12 g/d - courtesy of the food industry

80% of salt hidden in food

(a)

(b)

Processed

Fast

Restaurant

Canteen

Salt, diet & health. 1998, Camb Uni Press

• 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)

Evidence

12 6 3Salt Intake (g/day)

Systolic BP (mmHg)

Diastolic BP(mmHg)

Urinary Sodium(mmol/24h)

50

100

150

200

0

100

90

150

160

155

145

95

165

Randomised Double-Blind Crossover Study (N=20)

MacGregor et al. Lancet 1989;2:1244-7.

P<0.001 by repeated measures ANOVA.

P<0.001 by repeated measures ANOVA.

Hypertensive Normotensive

Fall in Systolic BP

(mmHg)

Usual salt intake

Reduced salt intake

Urinary Sodium (mmol/24h)

***

***

P<0.001 reduced salt vs. usual salt intake.

Meta-analysis of Modest Salt Reduction Trials of one month or Longer

J Hum Hypertens. 2002;16:761-770***

-2

0

-4

-6

100

50

150

0

-12

-10

-8

-6

-4

-2

0

2

4

-130-110-90-70-50-30

Change in Systolic BP

(mmHg)

Change in Urinary Sodium (mmol/24h)

Hypertensivesb=0.07, P<0.001

Normotensivesb=0.04, P<0.001

Dose Response: Meta-analysis (1 month or longer)

A 6 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)

J Human Hypertens 2002;16:761

Avg. 5 mmHg

Salt intake 5-6g/day

Stroke 24% CHD 18%

Worldwide 2.5 million (approx) deaths prevented / year

He & MacGregor. Hypertension 2003;42:1093-99

35,000 (approx) Stroke & heart attack deaths prevented / year

UK

1.6

1.4

1.2

1.0

0.8

0.6

0

Stroke CVD

Relative risk

Meta-analysis of cohort studies

5 g/d ↑salt intake is related to 23% ↑stroke and 17% ↑CVD

23% ↑ P=0.007

17% ↑ P=0.02

5 g/d higher salt

Strazzullo et al. BMJ 2009;339:b4567

5 g/d higher salt

0.12

0.16

0.08

0.04

0

0.10

0.08

0.06

0.04

0.02

02 64 12108 1614

CumulativeIncidence

of CVD

CumulativeIncidence

of CVD

TOHP I

TOHP II

Control

Salt reduction

Control

Salt reduction

0.20

Cook et al. BMJ 2007;334:885Follow- up (years)

Outcome trial

25% Salt intake (↓2.5 g/d) 25% CVD events

Japan

At this time Japan rapidly Westernised e.g. saturated fat, smoking, weight, exercise

1960 Government campaign to reduce salt intake

Akita (North): 18 → 14 g/day (4 g/day ↓ )

Overall: 13.5 → 12.1 g/day (1.4 g/day ↓ )

BP 80% in stroke mortality

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.

Year

Salt intake(g/day)

Finland

Diastolic BP(mmHg)

Stroke mortality(1/100000)

Year Year

Men

Women

Men

Women

Karppanen & Mervaala. Prog Cardiovasc Dis 2006;49:59-75.

• Measure salt intake

• Identify major contributors, e.g. bread, cereals, meat products, etc

Reducing salt intake

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

Fantastic for Public Health

Very little cost

Food industry slowly reduce - No rejection by public

No need to change diet

Hidden Salt in foode.g. processed, fast, takeaway, restaurant food

↓ BP

Consensus Action on Salt & Health (CASH)

• 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

Aims

www.actiononsalt.org.uk

THE UK EXAMPLE

• Members all experts on salt and BP

• Set up 1996 in response to rejection of salt reduction recommendations by UK Dept. of Health

CASH Strategy for Reducing Salt in UK

Table/Cooking (15%)

Natural (5%)

Food industry (80%)

0.9 g

0.5 g

4.6 g

40% reduction

No reduction

40% reduction

Salt intake Reduction needed

Total 9.5 g

1.4 g

0.5 g

7.6 g

Target 6.0 g

the food industry needs to slowly reduce salt content of all foods by 40% over the next 5 years

Source g/day

Target intakeg/day

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

• 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

Monitor salt intake

Perceived Barriers

1. Taste

2. Food technology

3. Safety

4. Commercial

SALT

Producers (40% by value)

Food IndustryHighly Salted Processed Food

Thirst

Soft DrinksMineral Water

Profit

Profit

Dependence on salty taste

(Salt Addiction)

Demand for very salty foods

Profit

Salt

Salt

Meat products

+ Salt

Salt

Weight No Cost

WaterBinding

Profit

Hidden Salt – Its Commercial Value

Sea Water Comparison(1.0 g of sodium / 2.5g of salt per 100g)

Pizza 60%

Chicken Curry 60%

Processed Cheese 130%

Bacon 200%

Sausages 100%

Smoked Fish 190%

Sweet Pickle 170%

Shepherds Pie 40%

Frozen Prawns 80%

Crisps 110%

Salad Cream 100%

Savoury Biscuits 70%

Medium Sliced White 50%

Granary Loaf 60%

Crumpets 80%

Digestive 60%

Cream Crackers 60%

Cheddar Cheese 70%

Stilton Cheese 90%

Processed Cheese 130%

Branflakes 100%

Cornflakes 110%

Tomato Ketchup 110%

Brown Sauce 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:

• Highlight foods high in salt

• Implement salt reduction plan

• Working with WHO

Individual Countries:

• Facilitate expert groups (similar to CASH) e.g. Canada, Australia

• Convince government of evidence, action by food industry

• Public health campaign to salt consumption at home

http://www.worldactiononsalt.com

To join, please contact wash@qmul.ac.uk

WASH Action Groups

1. 2010, USA adopt UK model. New York, FDA, CDC

Actions in other countries

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

2. 2010, Australia sets salt target

3. EU-WHO, European countries make a 16% reduction over 4 yrs.

4. WHO/PAHO South America

1. Salt intake BP

2. Salt intake (cheap/practical) → “Biggest improvement in public health since clean water and drains (19th Century)”

Summary Stroke Heart Attacks Heart Failure

Stomach Cancer & Osteoporosis

He & MacGregor. Reducing population salt intake worldwide: from evidence to implementation. Prog Cardiovasc Dis. 2010;52:363-382.