Sodium Intake and
Cardiovascular Disease:
Rationale for Policy Action
Thomas Farley, MD MPH
Joan H. Tisch Distinguished Fellow in Public Health Policy
Roosevelt House at Hunter College
Annual Estimated Reductions in
Deaths and Cardiovascular Events:
Comparison Across Various Interventions
Incidence of CHD
Death from any
cause
Low estimate
66,000 ± 5800
51,000 ± 7100
High estimate
110,000 ± 9200
81,000 ± 11,000
Smoking cessation
41,000 ± 10,000
84,000 ± 9300
Weight loss
59,000 ± 3500
36,000 ± 2000
Statin therapy
52,000 ± 5600
5400 ± 540
100,000 ± 11,000
80,000 ± 10,000
Intervention
Salt reduction: 3 g/day
Pharmacologic treatment of HTN
Source: Bibbins-Domingo K et al. Projected Effect of Dietary Salt Reductions on Future Cardiovascular Disease. 2010. New England Jounral of Medicine.
Background
•
•
Extremely common in U.S. and other “modern”
populations:
• High sodium consumption
• High blood pressure
• Cardiovascular disease
Questions:
• Does chronic high level of sodium consumption contribute to
•
high blood pressure and to cardiovascular mortality?
Would reductions in sodium consumption lead to reductions in
blood pressure and reductions in cardiovascular mortality?
•
Evidence Supporting Na+ Intake
Increases Cardiovascular Disease Risk
Animal studies
•
•
 Na ->  BP in many species, including primates
Observational studies in humans
•
BP -> Cardiovascular disease (CVD)
Prospective Studies Collaboration, Lancet, 2002
He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363
Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke.
Circulation 2011;123:1138
Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126
Stroke Mortality by Systolic BP
Definition of
Hypertension
Prospective Studies Collaboration, Lancet, 2002: Meta-analysis of 61 prospective studies
with 2.7m person-yrs, 11.9k deaths
•
Evidence Supporting Na+ Intake
Increases Cardiovascular Disease Risk
Animal studies
•
•
 Na ->  BP in many species, including primates
Observational studies in humans
•
•
BP -> Cardiovascular disease (CVD)
 Na -> BP in cross-sectional, multi-population studies
Prospective Studies Collaboration, Lancet, 2002
He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363
Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke.
Circulation 2011;123:1138
Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126
Sodium Intake vs. Blood Pressure
in 24 Populations
150
Systolic Blood Pressure
140
130
120
110
USA
Undeveloped
Developed
100
Isolated primitive
90
tribes
80
70
60
0
50
100
150
200
250
Sodium Intake (mmol/day)
Law MR et al, BMJ 1991;302:811-5
300
350
400
•
Evidence Supporting Na+ Intake
Increases Cardiovascular Disease Risk
Animal studies
•
•
Observational studies in humans
•
•
•
•
•
 Na ->  BP in many species, including primates
BP -> Cardiovascular disease (CVD)
 Na -> BP in cross-sectional, multi-population studies
 Na -> BP in migration studies
 Na -> CVD across most samples
Intervention trials (short term)
•
•
Treatment to BP -> CVD
Na intake -> BP in meta-analyses
Prospective Studies Collaboration, Lancet, 2002
He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363
Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke.
Circulation 2011;123:1138
Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126
Limiting Sodium Intake
Reduces Blood Pressure
135
130
135
125
130
125
120
Systolic Blood (mm
Pressure
Hg)(mm HG)
Systolic Blood Pressure
DASH-Sodium Trial
120
High
High 3,000 mg
3,450 mg/day
Intermediate
Intermediate 2,300 mg
2,300 mg/day
Low
Low 1,500 mg
1,150mg/day
Sodium Intake
Sacks FM et al. Effects on Blood Pressure of Reduced Dietary Sodium. NEJM. 2001 Jan 4;344(1):3-10
•
Evidence Supporting Na+ Intake
Increases Cardiovascular Disease Risk
Animal studies
•
•
Observational studies in humans
•
•
•
•
•
 Na ->  BP in many species, including primates
BP -> Cardiovascular disease (CVD)
 Na -> BP in cross-sectional, multi-population studies
 Na -> BP in migration studies
 Na -> CVD across most samples
Intervention trials (short term)
•
•
•
Treatment to BP -> CVD
Na intake -> BP in meta-analyses
Na intake ->  CVD across most samples
Prospective Studies Collaboration, Lancet, 2002
He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363
Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke.
Circulation 2011;123:1138
Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126
Effects of Reduced Na on CVD Events:
Results from 3 Randomized Trials
INTERVENTION OUTCOME
TONE (2001)
639 Elderly
Taiwan Veterans
(2006) 1,981 Elderly
TOHP Follow-up (2007)
3,126 Prehypertensives
↓ Na
↓ Na /↑ K
Salt
↓ Na
FU
21% ↓
CVD events
2.3 yrs
41%* ↓
CVD
Mortality
2.6 yrs
30%* ↓
10-15 yrs
CVD events
*p<0.05
•
Evidence Supporting Na+ Intake
Increases Cardiovascular Disease Risk
Animal studies
•
•
Observational studies in humans
•
•
•
•
•
BP -> Cardiovascular disease (CVD)
 Na -> BP in cross-sectional, multi-population studies
 Na -> BP in migration studies
 Na -> CVD across most samples
Intervention trials (short term)
•
•
•
•
 Na ->  BP in many species, including primates
Treatment to BP -> CVD
Na intake -> BP in meta-analyses
Na intake ->  CVD across most samples
Population interventions
•
Na intake associated with  CVD mortality in Japan, Finland, U.K.
Prospective Studies Collaboration, Lancet, 2002
He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363
Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke.
Circulation 2011;123:1138
Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126
Successful Labeling Model:
Finland
•
•
•
•
1970s: begin focus on sodium reduction
1993: required "high salt content" warning on
packaged food
1979-2002: salt intake ↓ 23% in men and 28% in
women
Over three decades coronary heart disease
deaths reduced by 80% in middle aged adults
Karppanen, H., and Mervaala, E. Sodium Intake and Hypertension. Progress in Cardiovascular Diseases. 2006;
49 (2):59-75.
Laatikainen, T. et al. Sodium in the Finnish Diet: 20-year trends in urinary sodium excretion among the adult
•
Evidence Supporting Na+ Intake
Increases Cardiovascular Disease Risk
Animal studies
•
•
Observational studies in humans
•
•
•
•
•
BP -> Cardiovascular disease (CVD)
 Na -> BP in cross-sectional, multi-population studies
 Na -> BP in migration studies
 Na -> CVD across most samples
Intervention trials (short term)
•
•
•
•
 Na ->  BP in many species, including primates
Treatment to BP -> CVD
Na intake -> BP in meta-analyses
Na intake ->  CVD across most samples
Population interventions
•
Na intake associated with  CVD mortality in Japan, Finland, U.K.
Prospective Studies Collaboration, Lancet, 2002
He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363
Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke.
Circulation 2011;123:1138
Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126
Leading Health Care Organizations Agree:
Na Intake Must be Reduced
•
•
•
•
•
•
American Medical Association (AMA)
American Heart Association (AHA)
American Public Health Association (APHA)
Institute of Medicine (IOM)
National Heart, Lung, and Blood Institute (NHLBI)
World Health Organization (WHO)
•
Evidence Supporting Na+ Intake
Increases Cardiovascular Disease Risk
Animal studies
•
•
Observational studies in humans
•
•
•
•
•
BP -> Cardiovascular disease (CVD)
 Na -> BP in cross-sectional, multi-population studies
 Na -> BP in migration studies
 Na -> CVD across most samples
Intervention trials (short term)
•
•
•
•
 Na -> BP in many species, including primates
Treatment to BP -> CVD
Na intake -> BP in meta-analyses
Na intake ->  CVD across most samples
Population interventions
•
Na intake associated with  CVD mortality in Japan, Finland, U.K.
Prospective Studies Collaboration, Lancet, 2002
He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363
Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke.
Circulation 2011;123:1138
Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126
“Definitive” Intervention Trial?
• Randomized controlled trial of 28,000
•
people for >5 yrs to low vs. high Na intake
Not feasible
• Compliance?
• 80% Na comes from processed food
• 5 years?
• Ethics?
Current U.S. Recommendations
And Disagreements
• U.S. Dietary Guidelines for Na intake
• <2,300 mg/day for low-risk
• <1,500 mg/day for those >50 yrs, blacks, those
with hypertension, renal disease, diabetes
• IOM recommendations (new)
• <2,300 mg/day for all
• “insufficient evidence to determine” if < 1,500 mg
Sodium Consumption in U.S.
U.S. adults, 20-74 years
Salt consumption (mg/day)
4,000
3,500
NSRI 5 yr
Goal
3,000
2,500
2005 U.S. Dietary Guidelines
recommendation for adults
2,000
1,500
Recommended limit for people with
hypertension, blacks, middle aged and older
1,000
500
0
NHANES I
1971-74
NHANES II
1976-80
NHANES III
1988-94
NHANES IV
1999-00
Briefel RR, Johnson CL. Secular trends in dietary intake in the United States. Annu Rev Nutr. 2004;24:401-431
Not All Disagreement is Healthy
Scientific Skepticism
• Salt Institute
•
Membership is global salt-producing companies
• E.g. Cargill, Morton Salt, International Salt Company, United
Salt Corporation
• Attack science showing that salt intake is unhealthy
•
Some leading critics funded by Salt Institute
•
E.g. David McCarron (220 scientific publications)
Lead Poisoning: Symptom of A
Deeper Problem?
• “[LIA’s lead expert at Harvard Joseph Aub]
felt that children that have subnormal
appetites, or the disease known as ‘pica’
which caused them to chew on inedible
articles, were subnormal to start with!”
• Felix Wormser, Secretary of Lead Industry Association (LIA) in
response to study on association between lead levels and
learning/behavior problems, 1944
Markowitz & Rosner, “Deceit and Denial: The deadly politics of industrial pollution.” U of CA Press,
2002. Chapter 2
Value of Scientific Doubt
• Strong tendency in public policy-making
•
toward inaction
Opponents need not prove anything
• Doubt is often sufficient to paralyze action
• Think climate change
Na Consumption in Paleolithic Era
•
•
Humans hunter-gatherers
Diet – all low in Na
•
•
•
•
•
•
•
•
•
Fruit & berries
Nuts
Seeds
Roots, tubers
Meat
Fish
Insects
Salt in short supply -> craving
Estimated Na consumption < 1,000 mg/day
Lindeberg S. Am J Hum Biol 2012;24:110-115
Konner M, Eaton SB. Nutr Clin Practice 2010;25:594
Key Questions - Reframed
• Does chronic high level of sodium
•
•
consumption contribute to high blood
pressure and to cardiovascular mortality?
Would reductions in sodium consumption
lead to reductions in blood pressure and
reductions in cardiovascular mortality?
Is it safe to feed people 3-4x as much Na
as we evolved eating?
Conclusions
• Scientific evidence, taken in its entirety,
makes compelling case that Na intake is
far too high
• Leading to high blood pressure and
unnecessary heart disease and stroke
• We should reduce Na in food supply
• Inaction is dangerous
• Tens of thousands of unnecessary deaths per
year