Sodium & Stroke Too much of a good thing… 2009 Preventing Strokes One At a Time

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

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 years and to 1200 mg for persons > 70 years. A daily upper limit of 2300mg should not be exceeded by any age group.  See for sodium intake guidelineswww.sodium101.ca CMAJ 2008;179(12 Suppl):E1-E93 #2.1

Recommendations for Adequate Sodium Intake by Age AgeSodium Intake per Day (mg) 0-6 months months years years1, years1, years1,300 > 70 years1,200 CMAJ 2008;179(12 Suppl):E1-E93 #2.1

High Blood Pressure: Major Component of Chronic Disease Risk Proportion of incidence due to high blood pressure ( Systolic >115 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 :1747

High Blood Pressure: Sick Populations  Study of Kenyan nomads and London civil servants  Average systolic BP in nomads=118 mmHg  Average systolic BP in civil servants = 138 mmHg Rose G. Int. J. Epi : 32-38

Canada’s Population is Sick! *2005 Ontario data. CMAJ : % adults and 52% of seniors have hypertension* Prevalence increased by 60%* Is getting Sicker! And is expected to get Worse! Further 60% increase in prevalence projected by 2025 Lancet :217

Key Public Heath Question 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 Why is hypertension largely absent in some populations while in others it is common?

Salt (Sodium) and Hypertension  Sodium  Low consumption of fruits & vegetables  Weight  Low exercise  Alcohol in excess

A Brief History… The Yellow Emperor’s 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” *Veith, I. (Translator) U of California Press,  For millions of years daily sodium intake < 400 mg/day - genetically programmed level  Recent change to 3-4,000 mg/day - a major physiological challenge

Salt: Increasing the Pressure 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 :64 ). Mechanisms by which dietary sodium increases arterial pressure are not fully understood

Sodium and Blood Pressure  Animal studies  Human Genetic Studies  Epidemiological Studies  Migration studies  Interventional Studies  Treatment Studies Evidence:

Animal Studies  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 *Nature Med 1995; 1: InterventionChange 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 weeksControl levels Similar study (127 chimps) finds effect of  Na + on  B.P. persists over 2 year time course (Circulation :1563).

Treatment Study: DASH Sodium  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 NEJM 2001; 344:3-10 InterventionChange in mean B.P. vs. control (systolic) Control dietDASH diet 9g/d saltControl level- 6 mmHg 6g/d salt- 2 mmHg- 7 mmHg 3g/d salt- 7 mmHg- 9 mmHg -7 Randomized 412 adults (mixed B.P. status, racial groups, sexes) to: -7 (NT) -11(HT)

Blood Pressure and Stroke 30% reduction in risk 10 mmHg 35% strokes*65% strokes* Based on trial data n =190,000 Stroke :1024 *Registry data

Blood Pressure and Stroke  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 >30%  Mean systolic B.P. reductions of 5-10 mmHg are potentially achievable by reducing sodium consumption. -7

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

Public Health Impact ~3,500 mg/day (current) ~1,500 mg/day (AI) Decrease hypertension prevalence by 30% (CJC :437) Prevent 30 premature deaths per day from Stroke and IHD, ~15% all CV events (CJC :497) Likely positive impact on obesity, osteoporosis, stomach cancer, kidney disease, asthma, etc… BP  ~5 mmHg

Sodium in our Food: Hard to Avoid Food (CCHS 2004 data)% Pizza, sandwiches, subs, burgers, hot dogs*19.1 Soups7.4 Pasta5.7 Liquid milk products4.0 Poultry and poultry dishes3.8 Potatoes3.4 Cheese3.2 Cereals3.0 *Breads14.0

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

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

Reducing Canada’s 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

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

Sodium & Stroke   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 Sodium Website

Canadian Best Practice Recommendations for Stroke Care, updated