Volume 89, Issue 4, April (2003), pp. 499-509 © The Author 2003
doi:10.1079/BJN2002809

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Cadmium absorption and retention by rats fed durum wheat (Triticum turgidum L. var. durum) grain*

W. A. House, J. J. Hart, W. A. Norvell and R. M. Welch^*
USDA-ARS, Plant, Soil and Nutrition Laboratory, Cornell University, Ithaca, NY 14853, USA

 (Received 12 June 2001–Revised 29 July 2002–Accepted 8 November 2002)

A whole-body radioassay procedure was used to assess the retention and apparent absorption by rats of Cd in kernels of durum wheat (Triticum turgidum L. var. durum) harvested from plants grown hydroponically in ¹⁰⁹Cd-labelled nutrient solution. Wholegrain wheat, containing 5 μmol Cd (570 μg)/kg dry weight labelled intrinsically with ¹⁰⁹Cd, was incorporated into test meals fed to rats that had been maintained on diets containing marginally adequate, adequate or surplus levels of Zn (0·12 mmol (8 mg), 0·43 mmol (28 mg) or 1·55 mmol (101 mg) Zn/kg respectively), and either 0 or 50 g durum wheat/kg. Regardless of diet, all rats consumed about 99 % of the test meal offered. In rats fed diets without wheat, initial Cd absorption averaged 7·7, 4·6 and 2·4 % of the dose when the diet contained 0·12 mmol (8 mg), 0·43 mmol (28 mg) or 1·55 mmol (101 mg) Zn/kg diet respectively. In rats fed wheat-containing diets, initial Cd absorption averaged 3·8 and 2·6 % of the dose when dietary Zn concentration was 0·12 mmol (8 mg) and 0·43 mmol (28 mg)/kg diet respectively. The amount of Cd retained in the body at 15 d postprandial was <2 % of the dose in all rats, and decreased as Zn in the diet increased. Even at 15 d postprandial, 32 to 44 % of the Cd retained in the body was still in the gastrointestinal tract. The results show that: (1) the bioavailability to rats of Cd in wholegrain durum wheat was depressed when wholegrain wheat was part of the regular diet; (2) increased intake of dietary Zn lowered Cd absorption and retention; (3) retention of Cd in the body at 15 d postprandial from diets containing adequate Zn was <1·3 %.

Abbreviations: MT; metallothionein; WOW8; diet without wheat, containing 0·12 mmol (8 mg) Zn/kg diet; WOW28; diet without wheat, containing 0·43 mmol (28 mg) Zn/kg diet; WOW101; diet without wheat, containing 1·55 mmol (101 mg) Zn/kg diet; WW8; diet with wheat, containing 0·12 mmol (8 mg) Zn/kg diet; WW28; diet with wheat, containing 0·42 mmol (28 mg) Zn/kg diet
Corresponding Author:  Dr Ross Welch, fax +1 607 255 2459, email RMW1@cornell.edu

Keywords:
Cadmium retention: Cadmium absorption: Durum wheat: Rats