Systemic effects of a high saturated fat diet in grizzly bears (Ursus arctos horribilis)

Abstract

Food sources for North America's grizzly bear (Ursus arctos horribilis Ord, 1815) population have changed as habitats have fragmented, altering available resources and putting bears in contact with unnatural foods. Bears have evolved mechanisms to tolerate obesity, and do not develop adverse health consequences despite storing massive amounts of body fat. Captive adult grizzly bears were used to determine the effects of dietary fat on health. Group 1 was fed a diet high in polyunsaturated fatty acids (PUFA) wherein 9.5% of available calories came from saturated fatty acids (SFA). Group 2 was fed a diet wherein 28.8% of calories came from SFA. Plasma fatty acids, serum lipid profiles, insulin, inflammatory markers, systolic and diastolic blood pressure, and cardiac function parameters were measured. Serum lipids, SFA, and insulin did not differ between the two groups, although omega-3 fatty acids differed. Bears eating the SFA diet had significantly higher circulating adiponectin, interleukin-7 and interleukin-15, and tumor necrosis factor-alpha. Mild, asymptomatic systolic and diastolic dysfunctions were detected by strain echocardiography in the SFA group. The SFA diet group exhibited higher diastolic arterial pressures. Even though mild metabolic derangements were observed, grizzly bears were remarkably resistant to metabolic effects of diets high in SFA.Key words: grizzly bears, Ursus arctos horribilis, hibernation, cardiac function, diastolic function, polyunsaturated fatty acids (PUFA), saturated fatty acids (SFA), inflammatory marker.Résumé : Les sources de nourriture de la population nord-américaine de grizzlis (Ursus arctos horribilis Ord, 1815) ont changé au fil de la fragmentation des habitats, modifiant du coup les ressources disponibles et exposant les grizzlis à des aliments non naturels. Les grizzlis ont développé des mécanismes de tolérance à l'obésité, et le stockage de grandes quantités de graisses corporelles n'a pas de conséquence néfaste sur leur santé. Des grizzlis adultes en captivité ont été utilisés pour déterminer les effets de la graisse alimentaire sur leur santé. Le groupe 1 a reçu un régime riche en acides gras polyinsaturés (AGPI) dans lequel 9,5 % des calories disponibles provenaient d'acides gras saturés (AGS). Le groupe 2 a reçu un régime dans lequel 28,8 % des calories provenaient d'AGS. Les acides gras plasmatiques, les profils de lipides sériques, l'insuline, des marqueurs d'inflammation, la pression sanguine systolique et diastolique et des paramètres associés à la fonction cardiaque ont été mesurés. Il n'y avait pas de différence entre les deux groupes en ce qui concerne les lipides sériques, les AGS et l'insuline, contrairement aux acides gras oméga-3. Les grizzlis nourris au régime riche en AGS présentaient des concentrations sériques d'adiponectine, d'interleukines 7 et 15 et du facteur de nécrose tumorale alpha plus élevées. De légères dysfonctions systolique et diastolique asymptomatiques ont été décelées par échocardiographie d'effort chez le groupe nourri au...

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