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Salt and Hypertension M.R.ABBASI MD,Nephrologist NRC TUMS 1993.

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Presentation on theme: "Salt and Hypertension M.R.ABBASI MD,Nephrologist NRC TUMS 1993."— Presentation transcript:

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2 Salt and Hypertension M.R.ABBASI MD,Nephrologist NRC TUMS 1993

3 Natrium=Sodium(Na) a metalic element with mol.Wt. 23gr

4 Chloride(Cl) a light green toxic gas with mol. Wt. of 35.5gr

5 5 TUMS-Nephrology Research Center

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9 Forms of Sodium 90% of sodium consumed as sodium chloride (salt, common salt, table salt,Halite) Other forms: –sodium bicarbonate –sodium in processed foods, such as sodium glutamate, sodium benzoate, sodium phosphate

10 Sodium Balance The human body contains 1 gr Na / Kg of BW 70 gr Νa = ~ 3000 mmol = 3000 meq Na Sodium is located to 95% extracellularly and to 5% intracellularly. Every 6 gr salt contains 2.3 gr( 100mmol=100meq ) of Na

11 NaCl Salt is composed of 40% Na and 60% Cl. Sodium together with potassium is an essential mineral for regulating body fluid balance. It is also essential for the transmission of the nerve and muscle impulses. Physiologic need of salt is only about 0.5 gr/day(current use is 9-12gr). High salt using is an acquired addiction for salt by consumption of processed foods.

12 Adverse Effects of Excess Salt Intake Established relationship –Increased blood pressure Probable relationship –Gastric and Colorectal cancer Suggestive relationship –Increased risk of osteoporosis –Increased risk of nephrolithiasis –Increased left ventricular mass Hypothesized relationship –Overweight/obesity –asthma → CVD and Stroke

13 P. A. Gilbert* and G. Heiser: Salt and health British Nutrition Fundation

14 The association between a high salt intake and hardened pulse was already known 4500 years ago. Cirillo M, Capasso G, Di Leo VA, De Santo NG. A history of salt. Am J Nephrol 1994;14: TUMS-Nephrology Research Center

15 Magnitude of BP Problem: Population Perspective Worldwide, cardiovascular disease (heart disease and stroke) is the leading cause of death 62% of strokes and 49% of CAD events attributed to elevated BP* 26% of adults worldwide (972 million) have hypertension** *WHO, World Health Report 2002: Reducing Risks, Promoting Healthy Life, **Kearney Lancet 2005;305:217

16 Genitourinary diseases Leading Causes of Death, Worldwide in 2002 Cardiovascular diseases Infectious and parasitic diseases Cancer Respiratory infections Respiratory diseases Unintentional injuries Perinatal conditions Digestive diseases Intentional injuries Neuropsychiatric conditions Diabetes mellitus Maternal conditions Congenital anomalies Nutritional deficiencies Others Number of deaths (x1000) 16TUMS-Nephrology Research Center

17 Major Underlying Factors causing Death - Worldwide Ezzati et al. Lancet 2002:360: Underweight Unsafe water, sani & hygiene Alcohol Physical inactivity High BMI Low fruit & vegetables intake Unsafe sex High cholesterol Tobacco Raised Blood Pressure Millions of Deaths 7 million Developing region Developed region 17TUMS-Nephrology Research Center

18 Types of Evidence Relating Salt Intake to Blood Pressure EpidemiologyOver 50 population studies MigrationSeveral GeneticAll defects identified so far impair the ability of the kidney to excrete salt. AnimalAll forms of hypertension are caused or aggravated by salt [rats, chimpanzees] TrialsChildren: ~10 trials, one trial in infants Adults: > 50 trials Population Interventions several 18TUMS-Nephrology Research Center

19 Primary hypertension is seen primarily in societies with average sodium intakes above 100 meq/day (2.3 g sodium( HTN is rare in societies with average sodium intakes of less than 50 meq/day (1.2 g sodium) HTN requires a threshold level of sodium intake. This effect appears to be independent of other risk factors for hypertension, such as obesity.

20 SBP Slope with Age (mmHg/yr) by Median Na Excretion in 52 Communities Worldwide INTERSALT BMJ 1988;297: ,150 2,300 3,450 4,600 5,750 Populations with No Rise in SBP with Age 20TUMS-Nephrology Research Center

21 Predicted Benefits of Reducing Sodium on Stroke and Heart Attack Deaths Reducing sodium by 400 mg/day would reduce  strokes by 5%  heart attacks by 3% Reducing sodium by 2,400 mg/day would reduce  strokes by 24%  heart attacks by 18% Hypertension 2003;42: TUMS-Nephrology Research Center

22 Effects of Reduced Na on CVD Events: Results from 3 Randomized Trials INTERVENTIONOUTCOMEFU TONE 1 (2001) 639 Elderly ↓ Na 21% ↓ CVD events 2.3 yrs Taiwan Veterans 2 (2006) 1,981 Elderly ↓ Na /↑ K Salt 41%* ↓ CVD Mortality 2.6 yrs TOHP Follow-up 3 (2007) 3,126 Prehypertensives ↓ Na 30%* ↓ CVD events yrs *p< Appel, Arch Int Med, 2001; 2 Chang, AJCN, 2006; 3 Cook, BMJ, 2007

23 Meta-Analyses of the Effect of Salt Reduction on Blood Pressure. Kotchen TA et al. N Engl J Med 2013;368:

24 Projected Estimates of Comparative Effect of Various Population Interventions on Annual Reductions in Cardiovascular Events. Bibbins-Domingo K et al. N Engl J Med 2010;362:

25 Estimated Changes in Systolic Blood Pressure Associated with Reductions in Dietary Salt. Bibbins-Domingo K et al. N Engl J Med 2010;362:

26 Estimated Changes in Systolic Blood Pressure Associated with Reductions in Dietary Salt. Bibbins-Domingo K et al. N Engl J Med 2010;362:

27 Effects of Sodium Reduction in Children: Results of a Meta-Analysis He and MacGregor, HTN Trials 966 Children Mean age=14 Median duration = 20wk 42% Reduction in Na

28 Salt sensitivity BP responsiveness to variations in salt intake is known as salt sensitivity % of hypertensives and a smaller percentage of normotensives are thought to have salt sensitive BP.

29 Factors Associated with Increased Salt Sensitivity Fixed factors –African-Americans –Middle and older-aged persons –Genetic Factors –Individuals with: Hypertension Diabetes Chronic Kidney Disease Low birth Wt Modifiable –Low potassium intake –Low Calcium intake –Poor quality diet –Obesity and metabolic syndrom.

30 Na sensitivity associated with: Insulin resistance Dyslipidemia Microalbuminuria Subtle renal injury

31 The fundamental defect in all hypertension is the kidneys' inability to excrete the excessive sodium load imposed by a high-salt diet. ( He & MacGregor, 2007).

32 Interrelated Salt-Induced Alterations That May Impair Sodium Excretion and Promote Vasoconstriction. Kotchen TA et al. N Engl J Med 2013;368:

33 Sodium retention(mechanisms) Increase activity of the proximal Na- H exchanger Increase Na reabsorption in thick ascending limb of henle loop by Na- K-2Cl cotransporter Increase Na reabsorption by distal Na-Cl cotransporter Increase Na reabsorption by ENaC in the collecting tubule.

34 Effect of low potassium diet Low K intake may increase the effect of Na on BP. Urinary Na:K ratio is more important than urinary sodium excretion only. K excretion less than 50 mmol/day was associated with rising 3.4 mmHg in SBP and 1.9 mmHg in DBP.(INTERSALT study).

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36 Sodium and Potassium in the Pathogenesis of Hypertension Horacio J. Adrogué, M.D., and Nicolaos E. Madias, M.D.NEJM356;19. May

37 Hakuo Takahashi et al, The cntral mechanism underlyinh HTN: a revew of the role of Na ions, ENaC, the R-A-A system, oxidative stress and endogenous digitalis in the brain:HTN research (2011)34,

38 Sodium and Potassium in the Pathogenesis of Hypertension Horacio J. Adrogué, M.D., and Nicolaos E. Madias, M.D.NEJM356;19. May

39 Sodium and Potassium in the Pathogenesis of Hypertension Horacio J. Adrogué, M.D., and Nicolaos E. Madias, M.D.NEJM356;19. May

40 Vasodilation failure Na loading causes vasodilation in Na insensitive subjects(by NO release). In Na sensitives Na loading causes an increase in Asymmetrical dimethylarginine which is endogenous inhibitor of NO.

41 Sources of Dietary Sodium Inherent 12% Food Processing 77% At the Table 6% During Cooking 5% Mattes and Donnelly, JACN, 1991; 10: 383 (62 adults who completed 7 day dietary records)

42 Na/K cotent of food Copyright 2005 Wadsworth Group, a division of Thomson Learning

43 Food labelling Standard format : --group 1(Big4): energy, protein, carbohydrates and fat. --group2(4+4): sugars, saturated fat, fiber and sodium(and not salt).

44 There is a significant variation in the levels of salt consumption between countries, and also significantly different patterns of consumption. In European and North American countries the main sources of dietary salt are processed foods, restaurant services, and catering, while in Asian and African countries the main sources are the salt used in cooking and sauces. The food industry uses salt in every food category to enhance flavor, condition dough, preserve foods, and retain moisture

45 World Action on Salt and Health(WASH) - increasing public awareness of the harmful effects of salt on health. -Reduction of salt use to less than 5-6 gr -getting food industry to decrease the amount of salt added to foods and clearing labelling on food products.

46 Recommendations for Sodium Intake (mg/d): US and WHO US 2005 Dietary Guidelines General Population< 2,300 (6gr salt) Hypertensives, blacks, adults (45+)<1,500 (4GR salt) World Health Organization<2,000 (5gr salt)

47 Institute of medicine recommends: Na intake 65mmol(3.8gr NaCl) for 70 yrs old mmol K(4.7gr) /day. Sodium and Potassium in the Pathogenesis of Hypertension Horacio J. Adrogué, M.D., and Nicolaos E. Madias, M.D.NEJM356;19. May

48 Nephrology Research Center Thank You


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