Recommendations for Dietary Salt Intake
Lawrence J Appel, MD, MPHProfessor 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. BAKERUniversity of Illinois, Champaign-Urbana
ODED BAR-ORMcMaster University, Hamilton, ON
KENNETH L. MINAKER Massachusetts General Hospital & Harvard Medical School, Boston
R. CURTIS MORRIS, JRUniversity of California, San Francisco
LAWRENCE M. RESNICKNew 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 ConversionsUseful Conversions
Adequate Intake (AI)
Upper 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 SodiumSources of Dietary Sodium
Inherent12%
FoodProcessing
77%
At the Table6%
During Cooking 5%
Mattes and Donnelly, JACN, 1991; 10: 383
(62 adults who completed 7 day dietary records)
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 Potential Adverse Effects of Excess Sodium IntakeExcess Sodium Intake
• Increased urinary calcium excretion (but no trials with bone mineral density or fractures)
• Increased left ventricular mass in cross-sectional studies (and one randomized trial)
• Increased risk of gastric cancer (ecologic studies, case-control studies)
• Increased blood pressure
Deaths fromStomach Cancer
(per 100,000Per year)
Adapted from Joossens, Int J Epi 1996;25:494-504
KOR
r=0.702P<0.001
JAPAN
CHI
POLCOL
HUN
POR
GDRITA
SPAFRG
CAN
FINNET
MALE.W
ARGDEN
BEL
USA
N.I
MEX
TOB
190
170
150
130
110
90
70
50
30
10
06 7 8 9 10 11 12 13 14
Salt Intake (grams/day)
ICE
Salt and Stomach Cancer: Ecological Analysis
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
Population-Based Strategy SBP Distributions
Stamler R. Hypertension1991;17:I-16–I-20.Stamler R. Hypertension1991;17:I-16–I-20.
Reduction in SBPmmHg
235
Reduction in SBPmmHg
235
% Reduction in Mortality % Reduction in Mortality
Reduction in BP
Reduction in BP
After Intervention
After Intervention
Before InterventionBefore Intervention
Stroke CHD Total
-6 -4 -3-8 -5 -4-14 -9 -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 TrialsSodium: Dose Response Trials
Luft, 1979 (14 non-hypertensive)
40
60
80
100
120
140
160
180
200
0.23(10)
6.9(300)
13.8(600)
18.4(800)
27.6(1200)
34.5(1500)
grams/day (mmol/day)
SBP (mm Hg)
DBP (mm Hg)
+7+2+5+1+1
+6+4+2+2+4
Sodium: Dose Response TrialsSodium: Dose Response Trials
MacGregor, 1989 (20 hypertensive)
406080
100120140160180200
1.1 (50) 2.3 (100) 4.6 (200)
grams/day (mmol/day)
SBP (mm Hg)
DBP (mm Hg)
+8* +8*
+4* +5*
Sodium: Dose Response TrialsSodium: Dose Response Trials
Johnson, 2001 (n=17 non-hypertensive elderly)
4060
80100120
140160
180200
0.92 (40) 2.1(90) 3.2(140) 5.5 (240) 7.8 (340)
grams/day (mmol/day)
SBP(mmHg)
DBP (mmHg)
+6.1
+7.6 +3.5
+0.3 +3.7 -0.1 +1.6
-0.7
0.001≤ P <0.01*
0.01≤ P <0.05*
Sodium: Dose Response TrialsSodium: Dose Response Trials
Johnson, 2001 (n=15 elderly with isolated systolic hypertension)
40
60
80
100
120
140
160
180
200
0.92 (40) 2.1(90) 3.2(140) 5.5 (240) 7.8 (340)
grams/day (mmol/day)
SBP (mmHg)
DBP (mmHg)
+9.0 +1.8 +4.1 +6.0
-0.3+3.1 +0.3 +3.4
0.001≤ P <0.01*
0.01≤ P <0.05*
Johnson, 2001 (n=8 elderly with systolic-diastolic hypertension)
406080
100120140160180200
0.92 (40) 2.1(90) 3.2(140) 5.5 (240) 7.8 (340)
grams/day (mmol/day)
SBP (mmHg)
DBP (mmHg)
+8.0 +4.1 +5.4 +0.7
-0.41.
+1.2 +1.6+3.0
0.001≤ P <0.01*
0.01≤ P <0.05*
Sodium: Dose Response TrialsSodium: Dose Response Trials
Sodium Dose Response Trials: DASH-Sodium Trial*
120
125
130
135
SystolicBlood
Pressure
Control Diet
DASH Diet
1.5 (65) 2.4 (106) 3.3 (143) Sodium Level: gm/d (mmol) per day
+2.1
+1.3+1.7
+4.6 +6.7p<.0001
+3.0P<.0001
*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 Non-African-Americans on the Control Diet
-12
-10
-8
-6
-4
-2
0
Ch
ang
e in
BP
Systolic BP Diastolic BP
African-Americans Non-African-Americans
- 8.0†
P<.001
- 4.5†
P<.001 - 5.1
P<.001
- 2.2
P<.001
0 † P-interaction < 0.05
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 OUTCOME FU
TONE (2001) 639 Elderly
↓ Na21% ↓
CVD events2.3 yrs
Taiwan Veterans (2006) 1,981 Elderly
↓ Na /↑ K Salt
41%* ↓CVD
Mortality2.6 yrs
TOHP Follow-up (2007) 3,126 Prehypertensives
↓ Na30%* ↓
CVD events10-15 yrs
*p<0.05
SETTING A LOWER LIMIT
Obligatory Losses of Sodium Obligatory Losses of Sodium (in g/d and mmol/d)(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
Total 0.040 to 0.185 1.7 to 8.0
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 Sodium Recommendations from IOM ReportIOM 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
Lawrence J. Appel, MD, MPH Johns Hopkins Medical Institutions, Baltimore, MD
Yvonne L. Bronner, ScD, RD, LD Morgan State University, Baltimore, MD
Benjamin Caballero, MD, PhDJohns Hopkins University Bloomberg School of Public Health, Baltimore, MD
Carlos A. Camargo, MD, DrPHHarvard University, Boston, MA
Fergus M. Clydesdale, PhD,University of Massachusetts, Amherst, Amherst, MA
Vay Liang W. Go, MD University of California at Los Angeles, Los Angeles, CA
Penny M. Kris-Etherton, PhD, RD Penn State University, University Park, PA
Joanne R. Lupton, PhDTexas A&M University, College Station, TX
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, MPHColumbia 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