Author
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Reeves, Phillip |
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Vanderpool, Richard |
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Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/28/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Cadmium is a trace element that is considered to be toxic when ingested in small amounts over a long period. Cadmium is found in most soils in differing amounts. Sunflowers grown in these soils tend to remove the cadmium and deposit it in the seeds. Because sunflower kernels are used as a snack food, we wanted to know how well this natural cadmium was absorbed from the seeds into the body. We used laboratory rats, both male and female, as models to study this process. Diets for the rats were made partly by using purified carbohydrate, protein, fat and all vitamins and minerals the rats needs to stay healthy. In addition, to the diets we added 20% ground sunflower kernels that contained differing amounts of cadmium, ranging from 120 to 195 micrograms per kilogram of diet (about 3 millionths of an ounce/lb). Rats that consumed diets containing 20% ground kernels for 15 weeks gained significantly more weight than those without kernels in their diets; however, the increased weight was not the result of increased feed intake. When the intake of dietary cadmium was increased two fold, as a result of feeding kernels, there was about a two fold increase the total amount of cadmium in the body of both male and female rats but male rats had more body cadmium than females. However, this increased amount was very, very small; about 560 nanograms or about 0.2 trillionths of an ounce. This study clearly showed that, even though small, the amount of cadmium in the tissues of rats can be increased by their consuming sunflower kernels with a natural abundance of cadmium. Technical Abstract: Sunflowers tend to remove cadmium (Cd) from the soil and deposit it in the seeds. The availability of this Cd in sunflower kernels (SFK) for absorption and deposition in animal tissues was studied by using a 15 wk feeding trial with both male and female weanling rats. Diets included, 1) purified basal diet with no SFK (85 ug Cd/kg), 2) basal diet containing 20% ground low-Cd SFK (120 ug Cd/kg), 3) basal diet containing 20% ground high-Cd SFK (195 ug Cd/kg), and 4) basal diet containing 20% ground low-Cd SFK plus CdCl2 (175 ug Cd/kg). In a second experiment, adult rats were fed SFK that contained an endogenous or exogenous label of 109**Cd. Cd availability was assessed by measuring 109**Cd excretion in feces and by measuring the amount of label accumulated in liver and kidney. Results were as follows: 1) Some groups of rats that consumed diets containing 20% ground SFK gained significantly (P<0.02) more weight than those without kernels in their diets. Increased weight was not the result of increased feed intake. 2) Increasing Cd intake two fold, as a result of feeding SFK, significantly (P<0.001) increased the body burden (total liver plus kidney content) of Cd from 1.6 to 4.0 nmol in females and from 4.0 to 7.0 nmol in males. 3) The availability of Cd in SFK labeled endogenously with 109**Cd was not different (P>0.1) than in kernels labeled exogenously; 12% vs. 15%, respectively. Eight days after dosing, total liver 109**Cd was 1% of the initial dose; at 20 days it was only 0.3%. The corresponding amounts in kidney were 0.1% and 0.2%, respectively. The amount of label in liver and kidney was not affected by the method of labeling the kernels. This study shows that Cd from SFK is available for absorption and accumulation in tissues of the rat, although in very small concentrations. |
