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Studies on the phytate: zinc molar contents in diets as a determinant of Zn availability to young rats

Published online by Cambridge University Press:  09 March 2007

N. T. Davies  and
S. E. Olpin
N. T. Davies
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
S. E. Olpin
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
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Abstract

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1. Studies were carried out in vitro to examine the effects of phytate on the solubility of the trace elements zinc, copper and manganese. Appropriate volumes of a solution of sodium phytate were added to a mineral solution to achieve phytate: Zn values of from 0: 1 to 45:1. In a second series the same values for phytate: Zn were achieved by varying the amount of added Zn at a fixed phytate concentration.

2. In both experiments > 85% of the Zn was rendered insoluble at pH 6.5 even at the lowest value for phytate:Zn (5:1). The effect of phytate on Zn solubility was greater than effects on Cu or Mn.

3. In a dietary study, rats were offered a semi-synthetic egg-albumin-based diet with added phytate. Two series of diets were prepared, the first had a constant Zn content (18.5 mg Zn/kg) and the amount of sodium phytate varied so as to achieve values for phytate: Zn of from 0:1 to 40:1 (series 1). In the second series, the same values for phytate:Zn were achieved by adding a fixed amount of phytate (7.4 g phytic acid/kg) while the amount of Zn was varied (series 2).

4. Dietary phytate caused significant reductions in growth rates, plasma Zn concentrations and hair Zn concentrations and greying of the coat at values for phytate:Zn of 15:1, 10:1, 10:1 and 15:1, respectively.

5. While phytate was apparently slightly more effective in reducing Zn status when phytate:Zn values were achieved at the lower absolute levels of phytate and Zn (series I diets), the differences at equivalent phytate:Zn values were small. It was concluded that phytate:Zn values can be used as an indicator of Zn availability from phytate-rich diets.

Rats offered three diets containing soya-bean-based textured-vegetable-protein (TVP) exhibited low rates of weight gain compared with rats offered an egg-albumen-based diet of similar Zn content (14.5 mg Zn/kg). Additional Zn supplied in drinking-water (25 mg Zn/l) was without effect on rats consuming the egg-albumin diet but significantly improved the weight gain of rats on the TVP diets.

7. It was concluded that phytate naturally present in TVP behaves similarly to phytate added to an otherwise phytate-free diet and that the reduced availability of Zn in TVP diets can be accounted for entirely by their phytate contents.

Type
Papers on General Nutrition
Information
British Journal of Nutrition , Volume 41 , Issue 3 , May 1979 , pp. 591 - 603
Copyright
Copyright © The Nutrition Society 1979

References

Davies, N. T. (1977). Proc. Symp. Child Nutrition and its Relation to Mental and Plzysical Development, p. 21. London: Kellogg Co. of Great Britain.Google Scholar
Davies, N. T., Hristic, V. & Flett, A. A. (1977). Nutr. Rep. int. 15, 207.Google Scholar
Davies, N. T. & Nightingale, R. (1975). Br. J. Nutr. 34, 243.CrossRefGoogle Scholar
Davies, N. T. & Reid, H. (1979). Br. J. Nutr. 41, 579.CrossRefGoogle Scholar
Edmunds, L. (1975). Daily Telegraph, 5 12. 1975.Google Scholar
Holt, R. (1955). J. Sci. Fd Agric. 6, 136.CrossRefGoogle Scholar
Likuski, H. J. A. & Forbes, R. M. (1965). J. Nutr. 84, 145.CrossRefGoogle Scholar
Maddaiah, V. T., Kurnick, A. A. & Reid, B. L. (1964). Proc. Soc. exp. Biol. Med. 115, 391.CrossRefGoogle Scholar
National Research Council (1972). Nutrient Requirements of Domestic Animals, No. 10. Nutrient Requirements of Laborutory Animals, p. 56. Washington, DC: National Research Council.Google Scholar
Oberleas, D. (1973). Toxicants Occurring Naturally in Foods, p. 363. Washington, DC: National Academy of Sciences.Google Scholar
Oberleas, D. (1975). Proc. Western Hemisphere Nutr. Congr. IV, p. 156.Google Scholar
Oberleas, D., Muhrer, M. E. & O'Dell, B. L. (1962). J. Anim. Sci. 21, 57.CrossRefGoogle Scholar
Oberleas, D., Muhrer, M. E. & O'Dell, B. L. (1966 a). In Zinc Metabolism, p. 225 [Prasad, A. S. editor]. Springfield, Ill.: Charles C. Thomas.Google Scholar
Oberleas, D., Muhrer, M. E. & O'Dell, B. L. (1966 b). J. Nutr. 90, 56.CrossRefGoogle Scholar
Rackis, J. J. (1974). J. Am. Oil Chem. Soc. 41, 161A.Google Scholar
Reinhold, J. G., Faraji, B., Abadi, P. & Ismail-Beigi, F. (1976). J. Nutr. 106, 493.CrossRefGoogle Scholar
Reinhold, J. G., McFoury, G. A. & Arslanian, M. (1968). J. Nutr. 4, 519.CrossRefGoogle Scholar
Ross, M., Welch, W. A. & Alloway, W. H. (1974). J. Nutr. 104, 733.Google Scholar
Vohra, P., Gray, A. & Kratzer, F. H. (1965). Proc. Soc. exp. Biol. Med. 120, 447.CrossRefGoogle Scholar
WHO (1973). Wld Hlth Org. Tech. Rep. Ser., NO. 532, p. 13.Google Scholar
Williams, R. B. & Mills, C. F. (1970). Br. J. Nutr. 24, 989.CrossRefGoogle Scholar