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Sodium Intake and Cardiovascular Disease: Rationale for Policy Action

Sodium Intake and Cardiovascular Disease: Rationale for Policy Action. Thomas Farley, MD MPH Joan H. Tisch Distinguished Fellow in Public Health Policy Roosevelt House at Hunter College. Annual Estimated Reductions in Deaths and Cardiovascular Events: Comparison Across Various Interventions.

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Sodium Intake and Cardiovascular Disease: Rationale for Policy Action

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  1. Sodium Intake and Cardiovascular Disease:Rationale for Policy Action Thomas Farley, MD MPH Joan H. Tisch Distinguished Fellow in Public Health Policy Roosevelt House at Hunter College

  2. Annual Estimated Reductions in Deaths and Cardiovascular Events:Comparison Across Various Interventions Source: Bibbins-Domingo K et al. Projected Effect of Dietary Salt Reductions on Future Cardiovascular Disease. 2010. New England Jounral of Medicine. 362:590-9.

  3. Background • Extremely common in U.S. and other “modern” populations: • High sodium consumption • High blood pressure • Cardiovascular disease • Questions: • Does chronic high level of sodium consumption contribute to high blood pressure and to cardiovascular mortality? • Would reductions in sodium consumption lead to reductions in blood pressure and reductions in cardiovascular mortality?

  4. Evidence Supporting Na+ Intake Increases Cardiovascular Disease Risk • Animal studies •  Na ->  BP in many species, including primates • Observational studies in humans • BP -> Cardiovascular disease (CVD) Prospective Studies Collaboration, Lancet, 2002 He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363 Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke. Circulation 2011;123:1138 Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126

  5. Stroke Mortality by Systolic BP Definition of Hypertension Prospective Studies Collaboration, Lancet, 2002: Meta-analysis of 61 prospective studies with 2.7m person-yrs, 11.9k deaths

  6. Evidence Supporting Na+ Intake Increases Cardiovascular Disease Risk • Animal studies •  Na ->  BP in many species, including primates • Observational studies in humans • BP -> Cardiovascular disease (CVD) •  Na -> BP in cross-sectional, multi-population studies Prospective Studies Collaboration, Lancet, 2002 He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363 Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke. Circulation 2011;123:1138 Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126

  7. Sodium Intake vs. Blood Pressure in 24 Populations USA Isolated primitive tribes Law MR et al, BMJ 1991;302:811-5

  8. Evidence Supporting Na+ Intake Increases Cardiovascular Disease Risk • Animal studies •  Na ->  BP in many species, including primates • Observational studies in humans • BP -> Cardiovascular disease (CVD) •  Na -> BP in cross-sectional, multi-population studies •  Na -> BP in migration studies •  Na -> CVD across most samples • Intervention trials (short term) • Treatment to BP -> CVD • Na intake -> BP in meta-analyses Prospective Studies Collaboration, Lancet, 2002 He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363 Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke. Circulation 2011;123:1138 Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126

  9. Limiting Sodium Intake Reduces Blood PressureDASH-Sodium Trial Sacks FM et al. Effects on Blood Pressure of Reduced Dietary Sodium. NEJM. 2001 Jan 4;344(1):3-10 Systolic Blood Pressure (mm Hg) 120 125 130 135 High Intermediate Low 3,450 mg/day 2,300 mg/day 1,150mg/day

  10. Evidence Supporting Na+ Intake Increases Cardiovascular Disease Risk • Animal studies •  Na ->  BP in many species, including primates • Observational studies in humans • BP -> Cardiovascular disease (CVD) •  Na -> BP in cross-sectional, multi-population studies •  Na -> BP in migration studies •  Na -> CVD across most samples • Intervention trials (short term) • Treatment to BP -> CVD • Na intake -> BP in meta-analyses • Na intake ->  CVD across most samples Prospective Studies Collaboration, Lancet, 2002 He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363 Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke. Circulation 2011;123:1138 Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126

  11. Effects of Reduced Na on CVD Events: Results from 3 Randomized Trials

  12. Evidence Supporting Na+ Intake Increases Cardiovascular Disease Risk • Animal studies •  Na ->  BP in many species, including primates • Observational studies in humans • BP -> Cardiovascular disease (CVD) •  Na -> BP in cross-sectional, multi-population studies •  Na -> BP in migration studies •  Na -> CVD across most samples • Intervention trials (short term) • Treatment to BP -> CVD • Na intake -> BP in meta-analyses • Na intake ->  CVD across most samples • Population interventions • Na intake associated with  CVD mortality in Japan, Finland, U.K. Prospective Studies Collaboration, Lancet, 2002 He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363 Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke. Circulation 2011;123:1138 Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126

  13. Successful Labeling Model: Finland • 1970s: begin focus on sodium reduction • 1993: required "high salt content" warning on packaged food • 1979-2002: salt intake ↓ 23% in men and 28% in women • Over three decades coronary heart disease deaths reduced by 80% in middle aged adults Karppanen, H., and Mervaala, E. Sodium Intake and Hypertension. Progress in Cardiovascular Diseases. 2006; 49 (2):59-75. Laatikainen, T. et al. Sodium in the Finnish Diet: 20-year trends in urinary sodium excretion among the adult population. Euro J Clin Nutr. 2006; 60: 965-970

  14. Evidence Supporting Na+ Intake Increases Cardiovascular Disease Risk • Animal studies •  Na ->  BP in many species, including primates • Observational studies in humans • BP -> Cardiovascular disease (CVD) •  Na -> BP in cross-sectional, multi-population studies •  Na -> BP in migration studies •  Na -> CVD across most samples • Intervention trials (short term) • Treatment to BP -> CVD • Na intake -> BP in meta-analyses • Na intake ->  CVD across most samples • Population interventions • Na intake associated with  CVD mortality in Japan, Finland, U.K. Prospective Studies Collaboration, Lancet, 2002 He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363 Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke. Circulation 2011;123:1138 Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126

  15. Leading Health Care Organizations Agree:Na Intake Must be Reduced • American Medical Association (AMA) • American Heart Association (AHA) • American Public Health Association (APHA) • Institute of Medicine (IOM) • National Heart, Lung, and Blood Institute (NHLBI) • World Health Organization (WHO)

  16. Evidence Supporting Na+ Intake Increases Cardiovascular Disease Risk • Animal studies •  Na -> BP in many species, including primates • Observational studies in humans • BP -> Cardiovascular disease (CVD) •  Na -> BP in cross-sectional, multi-population studies •  Na -> BP in migration studies •  Na -> CVD across most samples • Intervention trials (short term) • Treatment to BP -> CVD • Na intake -> BP in meta-analyses • Na intake ->  CVD across most samples • Population interventions • Na intake associated with  CVD mortality in Japan, Finland, U.K. Prospective Studies Collaboration, Lancet, 2002 He FJ and MacGregor GA. A comprehensive review of salt and health. J Hum Hypertension 2009;23:363 Appell LJ et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke. Circulation 2011;123:1138 Whelton PK et al. Sodium, blood pressure, and cardiovascular disease. Circulation 2012;126

  17. “Definitive” Intervention Trial? • Randomized controlled trial of 28,000 people for >5 yrs to low vs. high Na intake • Not feasible • Compliance? • 80% Na comes from processed food • 5 years? • Ethics?

  18. Current U.S. RecommendationsAnd Disagreements • U.S. Dietary Guidelines for Na intake • <2,300 mg/day for low-risk • <1,500 mg/day for those >50 yrs, blacks, those with hypertension, renal disease, diabetes • IOM recommendations (new) • <2,300 mg/day for all • “insufficient evidence to determine” if < 1,500 mg

  19. Sodium Consumption in U.S. NSRI 5 yr Goal U.S. adults, 20-74 years Salt consumption (mg/day) 2005 U.S. Dietary Guidelines recommendation for adults Recommended limit for people with hypertension, blacks, middle aged and older Briefel RR, Johnson CL. Secular trends in dietary intake in the United States. Annu Rev Nutr. 2004;24:401-431

  20. Not All Disagreement is Healthy Scientific Skepticism • Salt Institute • Membership is global salt-producing companies • E.g. Cargill, Morton Salt, International Salt Company, United Salt Corporation • Attack science showing that salt intake is unhealthy • Some leading critics funded by Salt Institute • E.g. David McCarron (220 scientific publications)

  21. Lead Poisoning: Symptom of A Deeper Problem? • “[LIA’s lead expert at Harvard Joseph Aub] felt that children that have subnormal appetites, or the disease known as ‘pica’ which caused them to chew on inedible articles, were subnormal to start with!” • Felix Wormser, Secretary of Lead Industry Association (LIA) in response to study on association between lead levels and learning/behavior problems, 1944 Markowitz & Rosner, “Deceit and Denial: The deadly politics of industrial pollution.” U of CA Press, 2002. Chapter 2

  22. Value of Scientific Doubt • Strong tendency in public policy-making toward inaction • Opponents need not prove anything • Doubt is often sufficient to paralyze action • Think climate change

  23. Na Consumption in Paleolithic Era • Humans hunter-gatherers • Diet – all low in Na • Fruit & berries • Nuts • Seeds • Roots, tubers • Meat • Fish • Insects • Salt in short supply -> craving • Estimated Na consumption < 1,000 mg/day Lindeberg S. Am J Hum Biol 2012;24:110-115 Konner M, Eaton SB. Nutr Clin Practice 2010;25:594

  24. Key Questions - Reframed • Does chronic high level of sodium consumption contribute to high blood pressure and to cardiovascular mortality? • Would reductions in sodium consumption lead to reductions in blood pressure and reductions in cardiovascular mortality? • Is it safe to feed people 3-4x as much Na as we evolved eating?

  25. Conclusions • Scientific evidence, taken in its entirety, makes compelling case that Na intake is far too high • Leading to high blood pressure and unnecessary heart disease and stroke • We should reduce Na in food supply • Inaction is dangerous • Tens of thousands of unnecessary deaths per year

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