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Sodium & Stroke Too much of a good thing…

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

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Sodium & Stroke Too much of a good thing…

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

  2. 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

  3. 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 > 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 2008;179(12 Suppl):E1-E93 #2.1

  4. Recommendations for Adequate Sodium Intake by Age CMAJ 2008;179(12 Suppl):E1-E93 #2.1

  5. 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 2006 367:1747

  6. 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. 1985 14: 32-38

  7. Canada’s Population is Sick! *2005 Ontario data. CMAJ 2008 178:1458 24% adults and 52% of seniors have hypertension* Is getting Sicker! 1995-2005 Prevalence increased by 60%* And is expected to get Worse! Further 60% increase in prevalence projected by 2025 Lancet 2005 365:217

  8. 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

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

  10. A Brief History… 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 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, 2002.

  11. 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 14:64).

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

  13. 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; 1:1009-16 • Similar study (127 chimps) finds effect of  Na+ on  B.P. persists over 2 year time course (Circulation 2007 116:1563).

  14. 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 -7 Randomized 412 adults (mixed B.P. status, racial groups, sexes) to: -7 (NT) -11(HT) NEJM 2001; 344:3-10

  15. Blood Pressure and Stroke Based on trial data n =190,000 Stroke 2004 35:1024 *Registry data 10 mmHg 30% reduction in risk 35% strokes* 65% strokes*

  16. 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 -7

  17. 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

  18. Public Health Impact ~3,500 mg/day (current) ~1,500 mg/day (AI) BP ~5 mmHg • Decrease hypertension prevalence by 30% (CJC 2007 23:437) • Prevent 30 premature deaths per day from Stroke and IHD, ~15% all CV events (CJC 2008 24:497) • Likely positive impact on obesity, osteoporosis, stomach cancer, kidney disease, asthma, etc…

  19. Sodium in our Food: Hard to Avoid

  20. 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

  21. 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

  22. 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

  23. 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

  24. www.sodium101.ca

  25. Sodium & Stroke 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 Sodium Website

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

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