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Transcript of Salt Presentation
How much is too much? By Jacqueline Lauer
Simone Passarelli Presentation Outline
1) Brief Introduction to salt
2) Arguments for limiting salt intake
3) Argume nts for not limiting salt intake
4) Recommendations and conclusions JAMA 2011: J-curve assocation between sodium excretion and CHF/CV hospitalizations and mortality
Intake over 7g or under 3g/day is associated with increased risk of stroke and CVD Is the rise in blood pressure a temporary phenomenon or a long-term medical concern?
Current consistent evidence that shows decrease in sodium intake decreases BP in hypertensive patients
Results not as consistent for CVD and stroke, no clear evidence
Discrepancy within groups and between study groups
Most studies are short term and small, and record few vascular effects
Even in meta-analyses! Cochrane Review 2011: meta-analysis of 7 studies (6,489 participants) on CVD morbidity/mortality
No effect of salt reduction on risk for mortality
Salt restriction increased risk for death in patients with heart failure Too much or too little may cause:
Electrolyte disturbance and neurological problems
Not enough sodium (salt) in the body fluids outside the cells. Acute Symptoms Sodium Intake 1971-2006
Individuals who have an impaired ability to excrete ingested salt, leading to an expansion of water volume in the blood vessels, and accompanying elevated blood pressure.
The following people should consume no more than 1,500 mg of sodium/day:
51+ year of age
High Blood Pressure
Chronic kidney disease Salt Sensitivity Associations may include….
High Blood Pressure
Left Ventricular Hypertrophy
Edema Potential Long Term Health Outcomes Adult humans contain about 250 grams of salt, but they are constantly losing it through bodily functions.
Most is sodium in the body is found in blood and lymph fluid. Controlled by a hormone called aldosterone.
Helps maintain the right balance of fluids in your body
Helps transmit nerve impulses
Influences the contraction and relaxation of muscles Salt in the Body
AI=1500 mg of sodium or 3750 mg of salt
UL=2300 mg of sodium or 5750 mg of salt
Our bodies need 180-500 mg daily for survival
Americans consume an average of 3,400 mg of sodium/day Recommended Daily Amounts Prehistoric Times
Present Day History of Salt Introduction to Salt Ionic compound produced by reacting an acid with a base.
Sodium Chloride (NaCl) = main ingredient in common table salt
Absolutely essential for human and animal life
Widely used as a seasoning and for the preservation of food throughout history and today
One of the basic human tastes
Produced from the evaporation of salt water or mining salt rock Relationship with stroke is unclear
Northern Manhattan Study 2012: food frequency questionnaire
Participants consuming >4000mg sodium, mostly hispanic and black populations, hazard ratio 2.59 compared to <1500mg/day
Opponents argued too many factors to link stroke outcome to sodium in particular
Meta-analysis of 13 studies (n=177,025) found statistically significant relationship between salt intake and cardiovascular disease
Limitations: follow up 3.5-19 years and did not adjust
Different methods for tracking salt intake Higher salt intake is associated with significantly greater incidence of strokes and total cardiovascular events, with a dose dependent association
A difference of 5 g a day in habitual salt intake is associated with a 23% difference in the rate of stroke and 17% difference in the rate of total cardiovascular disease
Each year a 5 g reduction in daily salt intake at the population level could avert some one and a quarter million deaths from stroke and almost three million deaths from cardiovascular disease worldwide Meta-analysis conclusions Three conclusions of DASH-Sodium, however long-term health benefits remain to be demonstrated and will depend on the ability of people to make long-lasting dietary changes, including the consistent choice of lower-sodium foods http://www.bmj.com/highwire/filestream/398814/field_highwire_article_pdf/0/bmj.b4567 There were 19 independent cohort samples from 13 studies, with 177,025 participants
1966 – 2008
Statistics were processed into a normalized distribution (using Stata!) to compare relative risk Salt intake, stroke, and cardiovascular disease: meta- analysis of prospective studies http://www.nejm.org/doi/pdf/10.1056/NEJM200101043440101 2001
412 participants were randomly assigned to eat either a control diet typical of intake in the United States or the DASH diet. Within the as- signed diet, participants ate foods with high, intermediate, and low levels of sodium EFFECTS ON BLOOD PRESSURE OF REDUCED DIETARY SODIUM AND THE DIETARY APPROACHES TO
STOP HYPERTENSION (DASH) DIET http://www.jhsph.edu/research/centers-and-institutes/johns-hopkins-center-to-eliminate-cardiovascular-health-disparities/research/PDFs/Appel.Dietary%20Patterns%20on%20BP.1997.pdf 1997
A diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. This diet offers a nutritional approach to preventing and treating hypertension. Dietary Approaches to Stop Hypertension (DASH) - Part I The evidence against
consuming salt Effects of Salt on Health CVD is the leading cause of death and disability worldwide
BP, cholesterol and smoking are the leading risk factors
For all ranges of BP starting at systolic 115
Salt has small, short-term effects?
Salt may also have other harmful effects
Increased risk of stroke, left ventricular hypertrophy, renal disease, stomach cancer, renal stones, obesity Salt's Effects on Plasma Renin Activity RAS: hormone that regulates BP and fluid balance
When salt intake is reduced, physiological stimulation of renin-angiotensin system
RAS is mechanism for stabilizing blood pressure
When salt intake, renin secretion in kidney , which raises angiotensin II levels
Angiotensin II stimulates aldosterone, reabsorption of sodium and water in blood -> BP , renal failure
This mechanism varies in different populations, and ACE inhibitors "Statistical significance does not necessarily mean practical significance."-Sean Cash Effects of Angiotensin II on Atherosclerosis Boxplot of Left Ventricular Mass Size and Angiotensin II Concentration Left ventricular hypertrophy can increase your risk of cardiovascular events by 2-5 times!! Conclusions In the end, everything is about $$-is it cost- effective?
Some studies show yes, for population-wide intervention
Population benefit: 30% experience small drop, 20% experience increase, residual no change- (Heart, 2011)
Harmful effects are seen below 2.4 mg intake...is it worth the risk? Sodium Intake from 1957-2003 in US (Am J Clin Nutr, 2010) Evidence against restricting salt intake Salt and Mortality Salt and Stroke Salar de Uyuni, Bolivia Salt Evaporation Ponds, Dead Sea Aigues-Mortes, France Maio Island, Cape Verde Our Recommendations Consumers: Education
& Motivation Where does our sodium come from? Currently, salt GRAS (generally recognized as safe)
> can add as much as want
Really, salt is GRAS at certain levels
Institute of Medicine Report to FDA:
Slowly decrease amount in stepwise manner
Partner with industry?
NSRI in NY
reduce salt intake by 20%
-restaurant & packaged foods
Concerns of limiting salt intake?
Food safety Regulation Good but not everyone is doing Industry Bulk of the evidence Average daily sodium intake = 3.4g
= 8.6 g salt = 1.5 tsp AI: 1.5g/day
(95% of Americans Exceed)
DASH diet: 2.3g/day
AHA: <1.5mg Best to slowly reduce dietary salt
Allow taste buds to adapt
Instead of salt use:
Herbs & spices What you can do Keep sodium content (mg) below calorie content. Questions? High Salt Sources:
Canned meats, soups
Condiments, pickled foods
Traditional snacks (pretzels, chips, crackers) (enhances flavor & preservative)
Eg: large order of cheese fries w/ ranch dressing: over 4000mg of sodium
General Mills & Nestle
Cutting 12% of sodium from cereals by 2015
Lowering salt content of flavored chips by 25%
Eg: Lays Sour Cream & Onion
Substituting other flavorings
What about traditional lays?
3 ingredients: potatoes, oil, salt
->developing new “salt”? Even nutrition students have high sodium intakes
Class average: 2.7g/day
Low sodium ≠ Tastes badly
2010: 800mg -> 480mg
2011: 480mg -> 650mg How Salt Raises Blood Pressure Leading Causes of Death in the United States 2005 Why should you care? Heart disease is the #1 killer in the United States
More cost-effective to eat less salt than treat hypertension with medications - it just makes sense!!! Feasibility and efficacy of sodium reduction
in the Trials of Hypertension Prevention 1992
327 active intervention and 417 control subjects
"Sodium Light Lifestyle"
Group meetings, food diaries and urine tests Support sodium reduction as a population strategy for hypertension prevention Trials of Hypertension Prevention D.A.S.H - There's two!!! Trials of Hypertension Prevention http://hyper.ahajournals.org/content/22/4/502 EFFECTS ON BLOOD PRESSURE OF REDUCED DIETARY SODIUM AND THE DIETARY APPROACHES TO
STOP HYPERTENSION (DASH) DIET determine whether the DASH diet could produce even better results if it were low in salt and also to examine the effects of different levels of sodium in people eating the DASH diet 3,000 mg, 2,400 mg or 1,500 mg/day 1988
INTERSALT confirmed that, over a wide range of sodium intake, populations with low sodium consumption have lower blood pressures than those with high sodium consumption Relative risk of stroke and cardiovascular disease