Phytase supplementation increases bone mineral density,lean body mass and voluntary physical activity in rats fed a low-zinc diet |
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| Authors: | Angus G. Scrimgeour Louis J. Marchitelli Jered S. Whicker Yang Song Emily Ho Andrew J. Young |
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| Affiliation: | 1. Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA;2. Department of Nutrition and Exercise Sciences, Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA;1. Laboratory of Comparative and Environmental Virology, Oswaldo Cruz Institute, Fiocruz, Av. Brazil 4365, Manguinhos, 21040-360 Rio de Janeiro, RJ, Brazil;2. Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, BA, Brazil;3. Laboratory of Clinical and Epidemiological Virology, Department of Microbiology and Immunology, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium;1. Department of Endocrinology, Command Hospital (Southern Command), Pune 411040, Maharashtra, India;2. Biochemistry Division, Department of Pathology, Deenanath Mangeshkar Hospital and Research Center, Erandawane, Pune, India;1. Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA;2. Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA;3. School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA;1. Departamento de Producción Animal, Facultad de Veterinaria, Universidad de Córdoba, Campus de Rabanales, Ed. Producción Animal, 14071 Córdoba, Spain;2. Unidad de Genómica y Mejora Animal, Departamento de Genética, Facultad de Veterinaria, Universidad de Córdoba, Campus de Rabanales, Ed. C-5, 14071 Córdoba, Spain;3. Instituto d Agricultura Sostenible, Av. Menéndez Pidal s/n, Campus Alameda del Obispo, 14080 CSIC, Córdoba, Spain |
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| Abstract: | Phytic acid forms insoluble complexes with nutritionally essential minerals, including zinc (Zn). Animal studies show that addition of microbial phytase (P) to low-Zn diets improves Zn status and bone strength. The present study determined the effects of phytase supplementation on bone mineral density (BMD), body composition and voluntary running activity of male rats fed a high phytic acid, low-Zn diet. In a factorial design, rats were assigned to ZnLO (5 mg/kg diet), ZnLO+P (ZnLO diet with 1500 U phytase/kg) or ZnAD (30 mg/kg diet) groups and were divided into voluntary exercise (EX) or sedentary (SED) groups, for 9 weeks. SED rats were significantly heavier from the second week, and no catch-up growth occurred in EX rats. Feed intakes were not different between groups throughout the study. ZnLO animals had decreased food efficiency ratios compared to both phytase-supplemented (ZnLO+P) and Zn-adequate (ZnAD) animals (P<.01 compared to ZnLO). The ZnLO+P and ZnAD rats ran 56–75 km more total distance than ZnLO rats (P<.05), with the ZnLO+P rats running more kilometers per week than the ZnLO rats by Week 6. In vivo DEXA analyses indicate that rats fed phytase-supplemented diets had higher lean body mass (LBM) than those fed ZnLO diets; and that rats fed the Zn-adequate diets had the highest LBM. Body fat (%) was significantly lower in EX rats and was both Zn- and phytase insensitive. Rats fed phytase-supplemented diets had higher bone mineral content (BMC), bone area (BA) and BMD than rats fed ZnLO diets; and in rats fed ZnAD diets these indices were the highest. The dietary effects on BMC, BA and BMD were independent of activity level.We conclude that consuming supplemental dietary phytase or dietary Zn additively enhances Zn status to increase BMD, LBM and voluntary physical activity in rats fed a low-Zn diet. While the findings confirm that bone health is vulnerable to disruption by moderate Zn deficiency in rats, this new data suggests that if dietary Zn is limiting, supplemental phytase may have beneficial effects on LBM and performance activity. |
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