Bioavailability of cadmium from infant diets in newborn rats

Abstract

Infants are exposed to higher levels of cadmium (Cd) from infant and follow-on formulas than from breast milk. We studied the bioavailability of 109CdCl2 from cows' milk formula, soy formula, wheat/oat/milk formula, wholemeal/milk formula and water in 11-day-old rat pups. The pups received a single oral dose of one diet labelled with 109Cd, 0.1 or 0.3 mg Cd/kg body weight. After 2 or 24 h or 4, 9 or 12 days the fractional retention of 109Cd in the whole body, in segments of rinsed small intestine and in tissue was measured in a gamma counter. Pups receiving 109Cd in water or cows' milk formula had the highest mean whole-body retention. It ranged from 67% of the dose in the water group to 52% in the wholemeal/milk formula group 4 days after dosing. The retention of 109Cd in the rinsed small intestine was significantly higher in the water group and the cows' milk formula group than in the cereal-based formula groups at 24 h and 4 days after dosing. It was still high in all groups on day 9, ranging from 26 to 11%. Initially most of the 109Cd was retained in the duodenum but by day 4 it had moved further down into the jejunum. In the liver, the highest and lowest retention on day 4 was 16%, and 3 per thousand of the dose in the water group and wholemeal/milk formula group, respectively. In the kidney, 109Cd was still increasing 12 days after exposure in all groups. Whole-body retention and tissue levels were higher than previously reported in adult animals. The lower bioavailability of 109Cd from the cereal-based formulas compared to water and cows milk formula on the longer survival times is most likely explained by Cd binding to dietary fibre and phytic acid in the cereal-based formulas reducing the intestinal binding and decreasing the bioavailability of Cd. The high retention of 109Cd in the small intestine, leading to a prolonged absorption period, emphasizes the importance of extending studies on neonatal Cd absorption over a long time period in order to detect for example, endpoints, accumulation of Cd in the kidney.

The effect of dietary selenium supplementation on cadmium absorption and retention in suckling rats

“…The average oral absorption of Cd is low, up to 5% in adult humans (WHO 1992). Data for human infants are not available, but animal experiments suggest somewhat higher absorption in newborns (Kostial et al 1978;Nordberg et al 1978;Eklund et al 2001). Lower levels of Cd (not significantly) and higher levels of Se in both urine and faeces of pups supplemented with Se (both Se pre ?…”

“…High and prolonged absorption of Cd, characteristic for newborn animals, is evident from the high level of Cd in the duodenum 24 h after the last Cd administration. Duodenum has been identified as the segment with the highest gastrointestinal Cd absorption in both adult (Sørensen et al 1993) and newborn animals (Eklund et al 2001). By tracking the retention of oral 109 Cd dose given in water or infant formula to 11-day-old rats, Eklund and co-workers also confirmed milk diet as a platform for higher Cd absorption and retention than water and cereal-or soy-based diets.…”

“…Higher gastrointestinal uptake of Cd in newborns on milk diet than in the weaning animals (Kostial et al 1978;Eklund et al 2001Eklund et al , 2004 prolongs Cd transport to the systemic circulation. Known adverse effects of Cd at such an early age prompted studies on trace element additives (Fe, Zn, Mn, Cu, Ca) to decrease Cd absorption in suckling rats (Kostial et al 1980;Matek Sarić et al 2002;Ö hrvik et al 2007).…”

Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis

“…The bioavailability of cadmium from cow's milk formula, soy formula, wheat/oat/milk formula, whole meal/milk formula and water were compared in rat pups [256]. The pups received a single oral dose of one diet labelled with 109 Cd, 0.1 or 0.3 mg Cd/kg body weight.…”

Dietary Deficiency of Calcium and/or Iron, an Age-Related Risk Factor for Renal Accumulation of Cadmium in Mice

“…Neonates are more sensitive to Cd toxicity than adults because of higher gastrointestinal absorption. 20 et al demonstrated that Cd transport in a model of neonatal intestinal cells correlated with expression of multidrug resistance-associated protein-1 but not with non-heme iron transporters such as DMT1. 22) Susceptibility of the intake and accumulation of Cd could vary depending on age.…”