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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Dietary Prevention of Obesity-related Disease Research » Research » Publications at this Location » Publication #91274
Title: INTERRELATION OF ZINC AND IRON NUTRITURE IN RATS

Author
item Zaslavsky, Boris
item Uthus, Eric

Submitted to: North Dakota Academy of Science Proceedings
Publication Type: Other
Publication Acceptance Date: 4/3/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: When setting a Recommended Dietary Allowance for a particular nutrient, rarely are other nutrients, which can effect or interact with that nutrient, taken into account. A more biologically meaningful approach should take into consideration these functional dependencies. Dietary copper (Cu) is known to interact with both zinc (Zn) and iron (Fe). The interaction between Fe and Zn, however, is poorly understood. To derive more biologically meaningful RDAs for Cu, Zn and Fe the interaction between Fe and Zn was studied further. Rats were fed diets containing varying amounts of Zn and Fe. After 7 weeks an interaction between Fe and Zn was seen in many of the parameters measured. For the most part, this interaction occurred when dietary Zn was low (between 5 and 10 æg/g) and Fe was moderately low or higher (greater than 12 æg/g). The results support the contention that interactive effects of Zn and Fe should be taken into consideration when deriving the RDA for these two elements. Also, because both Zn and Fe interact with Cu, the most biologically meaningful RDAs for Cu, Zn, and Fe should take all three elements into consideration.

Technical Abstract: Numerous physiological functions of zinc (Zn), copper (Cu) and iron (Fe) have been reported. Because of the interactions between Zn and Cu and between Cu and Fe, these elements can not be considered as independent nutrients. Therefore, any kind of independent Recommended Dietary Allowances (RDA) for Zn, Cu and Fe seems to be insufficient when the optimal supply of these elements is sought. A more biologically meaningful approach should take into consideration functional dependencies among Zn, Cu and Fe. Because little is known about the interaction between Fe and Zn a 5x4 factorially arranged experiment with laboratory rats was performed. Dietary variables were Fe at 4, 12, 24, 48 or 96 ug/g diet and Zn at 5, 10, 20 or 40 ug/g diet. Nonlinear models such as saturation curves and fractional power were used to fit the experimental data (as related to least square deviations) and reveal previously unreported patterns. After 7 weeks, the interaction between Fe and Zn was seen in many parameters. The interaction was dependent upon the amount of Fe and Zn in the diet. For example, when dietary Zn was >10 ug/g liver weight increased with increasing Fe (>12 ug/g); this data could be modeled by a saturation curve when Fe approached 96 ug/g. The response of the liver weight to Zn variations was almost negligible in this interval. The main conclusion is that a strong interaction between dietary Fe and Zn could be seen for Zn between concentrations of 5 and 10 ug/g when Fe was > 12 ug/g. The region of Zn < 10 ug/g and Fe between 4 and 12 ug/g was not covered sufficiently in this research and is in need of further investigation. The results support the contention that interactive effects of Zn and Fe should be taken into consideration when deriving the RDA for these two elements.