NUTRIBITES Webinar Series Sodium Too much too little

NUTRI-BITES® Webinar Series Sodium: Too much, too little or just right? November 6, 2014 Presenter: Robert P. Heaney, MD John A. Creighton University Professor/Professor of Medicine Creighton University Moderator: James M. Rippe, MD – Leading cardiologist, Founder and Director, Rippe Lifestyle Institute Approved for 1 CPE (Level 2) by the Commission on Dietetic Registration, credentialing agency for the Academy of Nutrition and Dietetics. Original recording of the November 6, 2014 webinar and PDF download of presentation available at: www. conagrafoodsscienceinstitute. com

NUTRI-BITES® Webinar Series Sodium: Too much, too little or just right? Based on this webinar the participant will be able to: Review the evolution of sodium intake recommendations Understand the physiology related to regulating sodium metabolism Discuss latest findings of the association of sodium intake to health outcomes Outline practical dietary strategies dietitians can offer clients as the science on sodium evolves

SOME SODIUM INTAKE FACTS § 2004 IOM recommendations for adults: < 1, 500 mg/day up to age 50 < 1, 300 mg/day from 50 to 70 < 1, 200 mg/day after age 70 § mean Na intake in U. S. & Europe: 3, 450 mg/day (95% probability range: 2, 600– 5, 000 mg/day) § this intake has been stable for at least 50 years in forty five 1 st world nations CU ORC

NUTRIENT RESPONSE CURVE* EAR RDA CU ORC UL *DRI book; IOM (2006)

RISK AT BOTH EXTREMES é deficiency toxicity è CU ORC 5

THE DRI PROCESS § first, the consequences of inadequate and excessive intakes are defined § data describing intakes needed to avoid those consequences is gathered § an intake just sufficient to avoid inadequacy is defined as the requirement § recognizing that individuals will have differing requirements, an average requirement is estimated (the EAR) CU ORC 6

THE SODIUM DRIs § the IOM noted that Na effects arose not from Na, per se, but from Na. Cl, the form in which ~90% of ingested Na enters the body § the IOM stated that there was not enough evidence regarding Na. Cl effects to establish the usual DRIs, and so proposed, instead, an AI CU ORC 7

THE SODIUM DRIs § the adverse effect with increasing salt intake, which the AI seeks to minimize, is elevated blood pressure § the IOM, in effect, ignored adverse effects at low intakes, i. e. , the panel used a linear model rather than a U-shaped model § this explains why the BP data and the health outcomes data disagree CU ORC 8

Health outcomes are the proxy STARTING INTAKE MATTERS é è CU ORC 9

CVD RISK vs. Na INTAKE § 17 country study § N = 101, 945 § mean follow-up: 3. 7 years § O’Donnell et al. NEJM 371: 612 (2014) 10

DASH–I* § three-way trial of dietary intervention standard American diet high in fruits and vegetables diet high in fruits & vegetables plus lowfat milk (~730 mg extra Ca) § Na intake held constant at ~3000 mg across all three diets *Appel et al. , NEJM 1997; 336: 1117 -24 CU ORC 11

DASH-I: Conclusions § BP reduction was as large as produced by standard anti-hypertensive monotherapy regimens § if applied at a population level, the full DASH diet would reduce incidence of stroke by 27 % MIs by 15 % CU ORC 12

DASH – ANOTHER CONCLUSION § the possibly harmful effects of high Na intake are magnified when the diet is inadequate in Ca and K § high Ca & K intakes mitigate the possible harm of high Na intakes CU ORC 13

THE NUTRIENT PROBLEM § the field lacks a consensus on how to define “normal” or “adequate” § that leaves the field virtually without a target to aim at § and forces reliance upon empirical evidence that, e. g. , intake A is “better” by some measurable endpoint than intake B § the evidence must be in the form of RCTs CU ORC 14

RAAS – A RESCUE MECHANISM ACE angiotensinogen renin â renal blood flow angiotensin II ou e: when y ic t o n t u b a. . . ake below t in a N e c redu te you activa l, e v le l a critic to raise BP y r t t a h t s mechanism á sympathetic activity áNa. Cl reabsorption & water retention áaldosterone secretion áarteriolar constriction & rise in BP á ADH secretion from pituitary 15

RISK CURVE FOR BP LOWERING § 5 -yr nonconcurrent cohort study § 398, 419 hypertensive pts. at Kaiser So. Cal § risk of death &/or ESRD § Sim et al. , J Am Coll Cardiol 2014; 64: 588 – 97 CU ORC

CONCLUSIONS § the risk curve for Na is the same as for other nutrients: U-shaped § risk of harm rises at both extremes of intake § the lowest risk range seems to be at about the current U. S. average Na intake § there is no evidence to justify efforts to decrease average salt intake § we should be emphasizing increasing Ca and K intakes, rather than decreasing Na intake CU ORC