Are the biodistribution and metabolic effects of copper nanoparticles dependent on differences in the physiological functions of dietary fibre?

Abstract The aim of the study was to determine the effect of the recommended (6.5 mg/kg) or enhanced (13 mg/kg) level of CuNPs in the diet in combination with different types of dietary fibre – cellulose (control), inulin, pectin, or psyllium on the Cu biodistribution and level of selected minerals parameters in the blood of rats. Rats were randomly divided into 10 groups. The first two groups were fed control diets containing cellulose and a mineral mixture with standard or enhanced content of CuCO3. Experimental groups were fed a diet supplemented with CuNPs (6.5 or 13 mg/kg) and combined with different types of fibre (cellulose, pectin, inulin, or psyllium). After the feeding period blood, liver, brain, and thigh samples were collected. In the samples of water, diet, urine, feces, liver, brain, and thigh the Cu content was determined to assess Cu biodistribution in the body. Additionally, the concentrations of minerals (Cu, P, Ca, Mg, Fe, and Zn) in the blood plasma samples were measured. The replacement of CuCO3 with CuNPs in the diet beneficially influenced the biodistribution of Cu in the body by reducing its excretion, improving its digestibility, and utilization, reducing its accumulation in the brain and muscle, and increasing levels of Ca, P, Mg, Zn and Fe in the blood. Increasing the level of CuNPs in the diet increased total Cu intake. The addition of pectin, inulin and psyllium to the diet with a high content of CuNPs significantly increased the excretion of Cu, with no negative effect on its digestibility, and utilization, and prevented its excessive accumulation in the brain and muscle of rats, especially in the case of inulin. The results suggest that the addition of dietary fibre to the diet of rats ensures homeostasis of this element in the case of excessive intake of CuNPs by modifying the bioavailability of Cu.