Published Online
on September 4, 2007

A more recent version of this article appeared on October 2, 2007

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Submitted on November 23, 2006
Accepted on July 20, 2007

Change in Salt Intake Affects Blood Pressure of Chimpanzees. Implications for Human Populations

Paul Elliott MB, PhD^*, Lesley L. Walker BSc, Mark P. Little MA, DPhil, John R. Blair-West MSc, PhD, Robert E. Shade PhD, D. Rick Lee DVM, Pierre Rouquet DVM, Eric Leroy DVM, PhD, Xavier Jeunemaitre MD, PhD, Raymond Ardaillou MD, Francoise Paillard MD, Pierre Meneton PhD, and Derek A. Denton MBBS

From the Department of Epidemiology and Public Health, Imperial College London, London, UK (P.E., M.P.L.); Howard Florey Institute of Experimental Physiology and Medicine (L.L.W.) and Department of Physiology (J.R.B.-W.), University of Melbourne, Melbourne, Victoria, Australia; Department of Physiology and Medicine, Southwest Foundation for Biomedical Research, San Antonio, Tex (J.R.B.-W., R.E.S., D.A.D.); University of Texas MD Anderson Cancer Center, Bastrop, Tex (D.R.L.); Centre International de Recherches Médicales de Franceville, Franceville, Gabon (P.R., E.L.); Université Paris Descartes, Faculté de Médecine, Paris (XJ); INSERM U772, Collège de France, Paris (X.J.); Hôpital Tenon, Paris, France (R.A., F.P.); INSERM U872, Département de Santé Publique et d’Informatique Médicale, Faculté de Médecine René Descartes, Paris, France (P.M.); and Baker Medical Research Institute, Melbourne, Victoria, Australia (D.A.D.).

^* To whom correspondence should be addressed. E-mail: p.elliott{at}imperial.ac.uk.

Background—Addition of up to 15.0 g/d salt to the diet of chimpanzees caused large rises in blood pressure, which reversed when the added salt was removed. Effects of more modest alterations to sodium intakes in chimpanzees, akin to current efforts to lower sodium intakes in the human population, are unknown.

Methods and Results—Sodium intakes were altered among 17 chimpanzees in Franceville, Gabon, and 110 chimpanzees in Bastrop, Tex. In Gabon, chimpanzees had a biscuit diet of constant nutrient composition except that the sodium content was changed episodically over 3 years from 75 to 35 to 120 mmol/d. In Bastrop, animals were divided into 2 groups; 1 group continued on the standard diet of 250 mmol/d sodium for 2 years, and sodium intake was halved for the other group. Lower sodium intake was associated with lower systolic, diastolic, and mean arterial blood pressures in Gabon (2-tailed P<0.001, unadjusted and adjusted for age, sex, and baseline weight) and Bastrop (P<0.01, unadjusted; P=0.08 to 0.10, adjusted), with no threshold down to 35 mmol/d sodium. For systolic pressure, estimates were -12.7 mm Hg (95% confidence interval, -16.9 to -8.5, adjusted) per 100 mmol/d lower sodium in Gabon and -10.9 mm Hg (95% confidence interval, -18.9 to -2.9, unadjusted) and -5.7 mm Hg (95% confidence interval, -12.2 to 0.7, adjusted) for sodium intake lower by 122 mmol/d in Bastrop. Baseline systolic pressures higher by 10 mm Hg were associated with larger falls in systolic pressure by 4.3/2.9 mm Hg in Gabon/Bastrop per 100 mmol/d lower sodium.

Conclusions—These findings from an essentially single-variable experiment in the species closest to Homo sapiens with high intakes of calcium and potassium support intensified public health efforts to lower sodium intake in the human population.

Key words: blood pressure • diet • hypertension • sodium

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