Recommendations for
Dietary Salt Intake
Lawrence J Appel, MD, MPH
Professor of Medicine, Epidemiology and
International Health
(Human Nutrition)
Oct 22, 2008
Dietary
Reference
Intakes
IOM Panel on Water and
Electrolytes
LARRY J. APPEL chair
Johns Hopkins University,
Baltimore, MD
DAVID H. BAKER
University of Illinois, ChampaignUrbana
ODED BAR-OR
McMaster University, Hamilton, ON
KENNETH L. MINAKER
Massachusetts General Hospital &
Harvard Medical School, Boston
R. CURTIS MORRIS, JR
University of California, San
Francisco
LAWRENCE M. RESNICK
New York Presbyterian Hospital &
Cornell University Medical College
MICHAEL N. SAWKA
U.S. Army Research Institute of
Environmental Medicine, Natick, MA
STELLA L. VOLPE
University of Pennsylvania,
Philadelphia
MYRON H. WEINBERGER
Indiana University School of Medicine,
Indianapolis
PAUL K. WHELTON
Tulane University Health Sciences
Center, New Orleans
ALLISON A. YATES
Study Director (from June 2003)
PAUL R. TRUMBO
Study Director (through May 2003)
Useful Conversions
Adequate
Upper
Intake (AI) Level (UL)
Sodium (g)
1.5
2.3
Sodium (mmol)
65
100
Sodium Chloride (g)
3.8
5.8
Forms of Sodium
•
•
90% of sodium consumed as
sodium chloride (salt)
Other forms:
–sodium bicarbonate
–sodium in processed foods,
such as sodium benzoate and
sodium phosphate
Sources of Dietary Sodium
(62 adults who completed 7 day dietary records)
Inherent
12%
Food
Processing
77%
At the Table
6%
During Cooking
5%
Mattes and Donnelly, JACN, 1991; 10: 383
Sodium Intake* at Baseline
by BMI Category
BMI Category
Non-Overweight
(n=44)
Overweight
(n=238)
Obese
(n=528)
mg of Na
2,991
3,708
4,235
% with Na
< 2,300 mg
32%
20%
11%
* as estimated from 24 Hour Urinary Sodium Excretion
SETTING AN
UPPER LIMIT
Potential Adverse Effects of
Excess Sodium Intake
•
•
•
•
Increased urinary calcium excretion (but no
trials with bone mineral density or fractures)
Increased left ventricular mass in crosssectional studies (and one randomized trial)
Increased risk of gastric cancer (ecologic
studies, case-control studies)
Increased blood pressure
Salt and Stomach Cancer: Ecological Analysis
190
KOR
170
r=0.702
P<0.001
150
130
Deaths from
110
Stomach Cancer
(per 100,000
90
Per year)
JAPAN
CHI
POL
COL
POR
70
HUN
GDR
50
ICE
30
MAL
BEL
E.W
DEN ARG
MEX
0
SPA
FRG
FIN
NET
N.I
TOB
10
ITA
CAN
USA
6
7
8
9
10
11
12
Salt Intake (grams/day)
Adapted from Joossens, Int J Epi 1996;25:494-504
13
14
Magnitude of the BP
Problem
•
•
•
62% of strokes and 49% of CHD events
attributed to elevated BP*
26% of adults worldwide (972 million)
have hypertension**
Estimated lifetime risk of developing
hypertension is 90%***
*WHO, World Health Report 2002: Reducing Risks, Promoting Healthy Life,
**Kearney Lancet 2005;305:217, ***Vasan, JAMA 2002;287:1003.
Stroke Mortality by Level of Usual Systolic BP*
*Prospective Studies Collaboration, Lancet, 2002: Meta-analysis of 61 prospective
studies with 2.7m person-yrs, 11.9k deaths
Population-Based Strategy
SBP Distributions
After
Intervention
Before
Intervention
Reduction
in BP
Reduction in SBP
mmHg
Stamler R. Hypertension
1991;17:I-16–I-20.
2
3
5
% Reduction in Mortality
Stroke CHD
Total
-6
-8
-14
-4
-5
-9
-3
-4
-7
Effect of Reduced Sodium Intake on
Blood Pressure
•
•
•
> 50 trials of sodium reduction on blood
pressure
10 dose response trials
3 trials of sodium reduction as a means to
prevent hypertension
Sodium: Dose Response Trials
200
SBP 180
(mm Hg) 160
140
+4
+2
+2
+1
+5
+4
+6
120
100
+1
+2
+7
80
DBP
(mm Hg) 60
40
0.23
(10)
6.9
(300)
13.8
(600)
18.4
27.6
34.5
(800) (1200) (1500)
grams/day (mmol/day)
Luft, 1979 (14 non-hypertensive)
Sodium: Dose Response Trials
200
SBP 180
(mm Hg) 160
140
120
100
80
DBP
(mm Hg) 60
40
+8*
+8*
+4*
1.1 (50)
+5*
2.3 (100)
4.6 (200)
grams/day (mmol/day)
MacGregor, 1989 (20 hypertensive)
Sodium: Dose Response Trials
200
SBP 180
(mmHg)
160
140
120
100
80
DBP
(mmHg) 60
40
+7.6
+3.5
+6.1
-0.7
0.001≤ P <0.01*
+0.3
+3.7
-0.1
+1.6
0.01≤ P <0.05*
0.92 (40)
2.1(90)
3.2(140) 5.5 (240) 7.8 (340)
grams/day (mmol/day)
Johnson, 2001 (n=17 non-hypertensive elderly)
Sodium: Dose Response Trials
200
180
SBP 160
(mmHg)
140
120
DBP 100
(mmHg) 80
60
40
+9.0
+1.8
+4.1
+6.0
0.001≤ P <0.01*
+3.1
+0.3
+3.4
-0.3
0.01≤ P <0.05*
0.92 (40) 2.1(90)
3.2(140) 5.5 (240) 7.8 (340)
grams/day (mmol/day)
Johnson, 2001 (n=15 elderly with isolated systolic hypertension)
Sodium: Dose Response Trials
200
SBP 180
(mmHg) 160
140
120
100
DBP
80
(mmHg) 60
40
+8.0
+4.1
+5.4
+0.7
0.001≤ P <0.01*
+3.0
-0.4
+1.2
+1.6
1
.
0.92 (40) 2.1(90)
0.01≤ P <0.05*
3.2(140) 5.5 (240) 7.8 (340)
grams/day (mmol/day)
Johnson, 2001 (n=8 elderly with systolic-diastolic hypertension)
Sodium Dose Response Trials:
DASH-Sodium Trial*
135
+2.1
Systolic
Blood
Pressure
130
Control Diet
+6.7
+4.6
p<.0001
+3.0
125
P<.0001
+1.3
+1.7
DASH Diet
120
1.5 (65) 2.4 (106)
3.3 (143)
Sodium Level: gm/d (mmol) per day
*Sacks, 2001 (412 prehypertensive and hypertensive adults)
Factors Associated with Increased
Salt Sensitivity
•
Fixed factors
–
–
–
–
Middle and older-aged persons
African-Americans
Genetic Factors
Individuals with:
• Hypertension
• Diabetes
• Chronic Renal Insufficiency
•
Modifiable
– Low potassium intake
– Poor quality diet
Effect of Sodium Reduction (Higher to
Lower) in African-Americans and NonAfrican-Americans on the Control Diet
Change in BP
0
African-Americans
Non-African-Americans
-2
- 2.2
-4
- 4.5†
-6
P<.001
-8
-10
-12
P<.001
- 5.1
P<.001
- 8.0†
P<.001
0 † P-interaction < 0.05
Systolic BP
Diastolic BP
Bottom Line on Sodium Chloride
•
The relationship between salt (sodium
chloride) intake and blood pressure is
direct and progressive without an
apparent threshold
Arguments Made by Those who
Oppose Sodium Reduction
•
•
•
•
No clinical trial has tested the effects of sodium
reduction on clinical cardiovascular outcomes
Only those who are ‘salt sensitive’ should reduce
their salt intake
Other lifestyle factors (weight, potassium, DASH
diet, exercise) are more important than sodium
Sodium reduction has effects on plasma renin
activity, lipids and insulin resistance that
potentially mitigate the beneficial effects of blood
pressure reduction
Effects of Reduced Na Intake on CVD: Longterm Results from
the Trials of Hypertension Prevention (Cook et al, BMJ, 2007)
Effects of Reduced Na on CVD Events:
Results from 3 Randomized Trials
INTERVENTION
TONE (2001)
639 Elderly
Taiwan Veterans
(2006) 1,981 Elderly
TOHP Follow-up (2007)
3,126 Prehypertensives
↓ Na
↓ Na /↑ K
Salt
↓ Na
OUTCOME
FU
21% ↓
CVD events
2.3 yrs
41%* ↓
CVD
Mortality
2.6 yrs
30%* ↓
CVD events
10-15 yrs
*p<0.05
SETTING A
LOWER LIMIT
Obligatory Losses of Sodium
(in g/d and mmol/d)
Source of Loss
g/d
mmol/d
Urine
0.005 to 0.035
0.2 to 1.5
Skin (nonsweating)
0.025
1.1
Feces
0.010 to 0.125
0.4 to 5.4
0.040 to 0.185
1.7 to 8.0
Total
Source: Dahl (1958)
Rationale for a Lower Limit
•
Nutrient Adequacy:
– ensure that the overall diet provides an
adequate intake of other important nutrients
•
Replacement of Sweat Losses:
– cover sodium sweat losses in unacclimatized
individuals who are exposed to high
temperatures or who are moderately
physically active.
Lower Limit: Two Caveats
•
•
The AI of 65 mmol/d does not apply to
highly active individuals, such as
endurance athletes, who lose large
amounts of sweat on a daily basis.
Inadequate sodium intake is not a public
health problem
Sodium Recommendations from
IOM Report
•
Upper Limit (UL):
2.3 g (100 mmol)/day for adults
•
Adequate Intake (AI):
1.5 g (65 mmol)/day for adults
2005 Dietary Guidelines

Scientific Advisory Committee Report
“Technical Report”

Dietary Guidelines for Americans, 2005
“Policy Document”

Finding Your Way to a Healthier You:
Based on the Dietary Guidelines for
Americans
“Public Document”

Implementation Tools

DASH eating plan

Food Label

My Pyramid

www.healthierus.gov/dietaryguidelines
2005 Dietary Guideline Scientific
Advisory Committee
Janet King, PhD, RD (Chair)
Children’s Hospital Oakland Research Institute,
Oakland, CA
Vay Liang W. Go, MD
University of California at Los
Angeles, Los Angeles, CA
Lawrence J. Appel, MD, MPH
Johns Hopkins Medical Institutions, Baltimore,
MD
Penny M. Kris-Etherton, PhD, RD
Penn State University,
University Park, PA
Yvonne L. Bronner, ScD, RD, LD
Morgan State University, Baltimore, MD
Joanne R. Lupton, PhD
Texas A&M University,
College Station, TX
Benjamin Caballero, MD, PhD
Johns Hopkins University Bloomberg School of
Public Health, Baltimore, MD
Carlos A. Camargo, MD, DrPH
Harvard University, Boston, MA
Fergus M. Clydesdale, PhD,
University of Massachusetts, Amherst, Amherst,
MA
Theresa A. Nicklas, DrPH, MPH, LN
Baylor College of Medicine,
Houston, TX
Russell R. Pate, PhD
University of South Carolina, Columbia, SC
F. Xavier Pi-Sunyer, MD, MPH
Columbia University College of Physicians and
Surgeons,
New York, NY
Connie M. Weaver, PhD
Purdue University, West Lafayette, IN
August 2004 Recommendations from
the Scientific Advisory Committee
1. Consume a variety of foods within and among the basic food
groups while staying within energy needs
2. Control calorie intake to manage body weight
3. Be physically active every day
4. Increase daily intake of fruits and vegetables, whole grains, and
reduced-fat milk and milk products
5. Choose fats wisely for good health
6. Choose carbohydrates wisely for good health
7. Choose and prepare foods with little salt
8. If you drink alcoholic beverages, do so in moderation
9. Keep food safe to eat
2005 Dietary Guidelines for Americans
from Policy Document
• 41 Key Recommendations in Dietary Guidelines
– 23 for General Public
– 18 for Special Populations
• 3 Key Messages in Consumer documents
– ‘Make smart choices from every food group’
– ‘Find your balance between food and physical
activity’
– ‘Get the most nutrition out of your calories’
SODIUM RECOMMENDATIONS
• For general population:
– consume less than 2,300 mg (approximately 1 teaspoon
of salt) of sodium per day
• For individuals with hypertension, blacks, and
middle-aged and older adults:
– consume no more than 1,500 mg of sodium per day