Sodium

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Preventing Strokes One At a Time
Sodium Stroke Too much of a good thing
2009
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Learning Objectives

• Upon completion, participants will be able to
• Practice according to the Canadian Best Practice
  Recommendations for Stroke Care, 2008 as it
  relates to sodium
• Educate patients on how sodium impacts their risk
  of stroke
• Counsel patients on their individual sources of
  sodium
• Partner with patients families to develop an
  individualized plan for risk factor management

Presentation used with permission of Dr. Kevin
Willis, Canadian Stroke Network
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Canadian Best Practice Recommendations for Stroke
Care, updated 2008

• 2.1 Sodium
• The recommended daily sodium intake from all
  sources is the Adequate Intake by age. For
  persons 9-50 years, the Adequate Intake is 1500
  mg. Adequate Intake decreases to 1300 mg for
  persons 50-70 years and to 1200 mg for persons gt
  70 years. A daily upper limit of 2300mg should
  not be exceeded by any age group.
• See www.sodium101.ca for sodium intake guidelines

CMAJ 2008179(12 Suppl)E1-E93 2.1
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Recommendations for Adequate Sodium Intake by Age
Age Sodium Intake per Day (mg)
0-6 months 120
7-12 months 370
1-3 years 1000
4-8 years 1,200
9-50 years 1,500
50-70 years 1,300
gt 70 years 1,200
CMAJ 2008179(12 Suppl)E1-E93 2.1
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High Blood PressureMajor Component of Chronic
Disease Risk

• Proportion of incidence due to high blood
  pressure (Systolic gt115 mmHg)
• Stroke 70-75
• Congestive Heart Failure 50
• Ischemic Heart Disease 25
• Renal Failure 20

High blood pressure is the leading cause of
mortality worldwide Lancet 2006 3671747
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High Blood Pressure Sick Populations

• Study of Kenyan nomads and London civil servants
• Average systolic BP in nomads118 mmHg
• Average systolic BP in civil servants 138 mmHg

Rose G. Int. J. Epi. 1985 14 32-38
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Canadas Population is Sick!
24 adults and 52 of seniors have hypertension
Is getting Sicker!
1995-2005 Prevalence increased by 60

• 2005 Ontario data. CMAJ 2008 1781458

And is expected to get Worse!
Further 60 increase in prevalence projected by
2025
Lancet 2005 365217
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Key Public Heath Question
Why is hypertension largely absent in some
populations while in others it is common?

• Not due to characteristics of individuals a
  shift in the whole distribution at the population
  level
• To make an impact on hypertension we need to
  control the factors that determine the population
  mean

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Salt (Sodium) and Hypertension

• Sodium
• Low consumption of fruits vegetables
• Weight
• Low exercise
• Alcohol in excess

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A Brief History
The Yellow Emperors Classic of Internal Medicine
written in China over 2,000 years ago
notes Hence if too much salt is used for food,
the pulse hardens

• For millions of years daily sodium intake lt 400
  mg/day - genetically programmed level
• Recent change to 3-4,000 mg/day - a major
  physiological challenge

Veith, I. (Translator) U of California Press,
2002.
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Salt Increasing the Pressure
Mechanisms by which dietary sodium increases
arterial pressure are not fully understood

• High sodium ? fluid retention ? B.P.?
• Kidneys ? excrete sodium ? fluid retention ? ?
  B.P. ?
• Prolonged high sodium intake may reset thresholds
  set by kidneys.
• Kidneys are less able to remove sodium as we age.
• Genes (14) responsible for Mendelian forms of
  hypo- or hypertension are all involved in renal
  sodium handling.
• Low dietary potassium ? renal sodium retention
  ?B.P.
• Signaling pathway in vasculature responds to
  ?sodium but does not regulate basal B.P. (Nat.
  Med. 2008 1464).

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Sodium and Blood Pressure
Evidence

• Animal studies
• Human Genetic Studies
• Epidemiological Studies

• Migration studies
• Interventional Studies
• Treatment Studies

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Animal Studies
Nature Med 1995 11009-16

• Chimps 2 groups of 13 (age 5-18y)
• Control group usual veg. fruit diet, low
  Na,high K
• Intervention group fed increasing amounts of salt
  over 84 weeks

Intervention Change in mean B.P. vs. controls
5g/d 19 weeks 12 mmHg (systolic)
10g/d 3 weeks, 15g/d 36 weeks 26 mmHg
15g/d 26 weeks 33 mmHg
0g/d 20 weeks Control levels

• Similar study (127 chimps) finds effect of ? Na
  on ? B.P. persists over 2 year time course
  (Circulation 2007 1161563).

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Treatment Study DASH Sodium
-7
Randomized 412 adults (mixed B.P. status, racial
groups, sexes) to

• Control diet - low in fruit, veg and dairy, fat
  content typical of US
• DASH diet - high in fruit, veg and low-fat dairy,
  reduced fat content
• Consume diet for consecutive 30 day periods in
  random order at each of 3 levels of salt

Intervention Change in mean B.P. vs. control (systolic) Change in mean B.P. vs. control (systolic)
Control diet DASH diet
9g/d salt Control level - 6 mmHg
6g/d salt - 2 mmHg - 7 mmHg
3g/d salt - 7 mmHg - 9 mmHg
-7 (NT) -11(HT)
NEJM 2001 3443-10
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Blood Pressure and Stroke
Based on trial data n 190,000 Stroke 2004
351024 Registry data
30 reduction in risk
10 mmHg
35 strokes
65 strokes
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Blood Pressure and Stroke
-7

• Clinical cut-off points do not reflect continuous
  relation between B.P. and health outcomes
• Normotensives get strokes too key is to
  reduce population risk!
• 10 mmHg reduction in systolic B.P. reduces
  individuals stroke risk by gt30
• Mean systolic B.P. reductions of 5-10 mmHg are
  potentially achievable by reducing sodium
  consumption.

-7
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Sodium (salt) in our Diet
Natural 15
Discretionary 15
Manufactured food processing 70
Health Minimum 180 mg/d
Reference Standard 2,400 mg/d (6.1 g salt)
Adequate Intake 1,500 mg/d (3.8 g salt)
Tolerable Upper Intake 2,300 mg/d (5.8 g salt)
3,000 4,000 mg/d (8-10 g salt)
Health Canada. Dietary Ref. Intake
Reports 2003 labeling legislation
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Public Health Impact

• 3,500 mg/day
• (current)

1,500 mg/day (AI)
BP? 5 mmHg

• Decrease hypertension prevalence by 30 (CJC 2007
  23437)
• Prevent 30 premature deaths per day from Stroke
  and IHD, 15 all CV events (CJC 2008 24497)
• Likely positive impact on obesity, osteoporosis,
  stomach cancer, kidney disease, asthma, etc

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Sodium in our Food Hard to Avoid
Food (CCHS 2004 data)
Pizza, sandwiches, subs, burgers, hot dogs 19.1
Soups 7.4
Pasta 5.7
Liquid milk products 4.0
Poultry and poultry dishes 3.8
Potatoes 3.4
Cheese 3.2
Cereals 3.0
Breads 14.0
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Sodium in our Food Why?

• Cheap way to boost flavor, texture and shelf
  life of poor quality foods
• Salt and sodium phosphates increase water
  binding capacity of meat products
• Salty snacks make you thirsty!

Food (fiber, nutrients, flavor) (salt,
sugar, fat) Processed food
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Sodium in our Food Would we miss it?

• Taste buds are used to high salt levels
• As salt levels are gradually reduced taste buds
  become more sensitive
• Studies have shown that it only takes a few weeks
  to enjoy food with less salt and reveal subtle
  flavors

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Reducing Canadas blood pressure

• Sodium reduction is easiest and most practical
  dietary change
• does not necessarily need a change in food choice
  provided less sodium added by food industry.
• Sodium reduction can be achieved by
• Clear labeling of all foods to which sodium is
  added
• Gradual reduction of sodium added to all foods
• A public campaign on health benefits

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Canada takes action

• Multi-stakeholder Working Group formed by Heath
  Canada
• Will follow international efforts (UK)
• Legislation if food industry does not meet
  voluntary targets

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www.sodium101.ca
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Sodium Stroke
Sodium Website

• http//www.lowersodium.ca
• Can link to a national sodium initiative with
  PowerPoint presentations for public and health
  care professionals if you like or continue for
  slide set developed and used with permission from
  Dr. Kevin Willis, Canadian Stroke Network

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Canadian Best Practice Recommendations for Stroke
Care, updated 2008 www.canadianstrokestrategy.ca